WO2018113887A2

WO2018113887A2 - A medical probe assembly

Info

Publication number: WO2018113887A2
Application number: PCT/DK2017/050445
Authority: WO
Inventors: Henriette Schultz KIRKEGAARD; André Hansen; Steen Møller Hansen
Original assignee: 3DIntegrated ApS
Current assignee: 3DIntegrated ApS
Priority date: 2016-12-20
Filing date: 2017-12-19
Publication date: 2018-06-28
Anticipated expiration: 2019-06-20
Also published as: WO2018113887A3; EP3558088A2; EP3558088A4

Abstract

A medical probe assembly for surgical and/or diagnostic use and a minimally invasive surgery instrument having a probe assembly is disclosed. The probe assembly has a rigid probe head, a light source and an optical fiber operatively connected to receive light from the light source and is coupled to the probe head for delivering light to the probe head. The light source comprises a laser diode. The probe head has a length and a maximal probe head dimension perpendicular to the probe length of up to about 2 mm and includes a beam collimating arrangement and a diffractive optic element (DOE). The beam collimating arrangement delivers beam expanded and collimated light to the DOE. The DOE is configured for structuring and emitting a structured light beam with a light intensity distribution forming a light pattern in image plan.

Description

A MEDICAL PROBE ASSEMBLY

TECHNICAL FIELD

The invention relates to a medical probe assembly for surgical and/or diagnostic use in particular suitable for use in minimally invasive surgery and diagnostic procedures.

BACKGROUND ART

Minimally invasive surgery (MIS) and minimally invasive diagnostics (MID) are increasingly used in the medical care to minimize patient trauma, to leave smaller or no scars, to minimize post-surgical pain and to enables faster patient recovery.

MIS includes generally all procedures performed through small incision in the skin of a patient or surgery performed through natural openings. MID includes all diagnostic procedure performed though natural openings and through small incision in the patient's skin.

MIS or MID performed through small incisions or natural openings is normally visualized for the surgeon by inserting a scope, such as an endoscope or a laparoscope which comprises illumination means and a camera into the body cavity and displaying the images on a screen. In order to improve the 3D surface determination for the surgeon, in particular to make it easier for the surgeon to determine the sizes of various organs, tissues, and other structures in a surgical site, several in-situ surgical metrology methods have been provided in the prior art. Different types of optical systems have been applied to provide an improved vision of the surgical site.

Also in other connections, it may be difficult or expensive to obtain 3D surface data from internal body cavity surfaces of a patient. The operator may for example use a CT scan to obtain the desired 3D surface data. Several prior art instruments for improving 3D surface determination by projecting a light pattern onto the target site have been suggested.

US 2013/0296712 describes an apparatus for determining endoscopic dimensional measurements, including a light source for projecting light patterns on a surgical site including shapes with actual dimensional measurements and fiducials, and means for analyzing the projecting light patterns on the surgical site by comparing the actual dimensional

measurements of the projected light patterns to the surgical site.

WO 2013/163391 describes a system for generating an image, which the surgeon may use for measuring the size of or distance between structures in the surgical field by using an invisible light for marking a pattern to the surgical field. The system comprises a first camera; a second camera; a light source producing light at a frequency invisible to the human eye; a dispersion unit projecting a predetermined pattern of light from the invisible light source; an instrument projecting the predetermined pattern of invisible light onto a target area; a band pass filter directing visible light to the first camera and the predetermined pattern of invisible light to the second camera; wherein the second camera images the target area and the predetermined pattern of invisible light, and computes a three-dimensional image. US2012310098 discloses a method for reconstructing a surface of a three- dimensional object involving a projection of a laser spot pattern, onto the surface of the three-dimensional object by a laser, and a generation of a series of endoscopic images as an endoscope is translated and/or rotated relative to the three-dimensional object. Several prior art documents disclose a light pattern emitting probe for being inserted through a lumen of a MIS instrument, such as through an

endoscope.

A major challenge for such pattern emitting probes is to make them

sufficiently small for being passed through the lumen in an endoscope or similar scope, while still providing a clear high contrast light pattern. The lumen of such scope often has a narrow diameter, such as a diameter of 3 mm or less, such as 2.8 mm or less or even as small as 2 mm.

US2016143509 describes a system for stereo reconstruction from a

monoscopic endoscope. The monoscopic endoscope comprises an image pickup element at a distal end thereof and a working channel defined by a body of the monoscopic endoscope. The working channel provides a port at the distal end of the monoscopic endoscope. The system for stereo reconstruction comprises a light patterning component configured to be disposed within the working channel of the monoscopic endoscope such that a light emitting end of the light patterning component will be fixed with a defined relative distance from the distal end of the image pick-up element. The light patterning component forms a pattern of light that is projected onto a region of interest and a data processor is configured to receive an image signal of the region of interest that includes the pattern, and to determine a distance from the endoscope to the region of interest based on the image signal and based on the defined relative distance between the light emitting end of the light patterning component and the distal end of the image pick-up element.

The light patterning component may include an illumination source, such as a laser, a transmission component, such as an optical fiber having a first end axially aligned with the illumination source and a pattern formation

component, such as a lens or diffraction grating adhered to a second end of the transmission component.

US 2013038836 describes a pattern-generating intraocular probe that includes a cannula including a diffractive optical element (DOE); the DOE being patterned such that an on-axis illumination of the DOE produces an emitted beam forming a linear pattern. The probe comprises a hand piece with the laser and a battery for powering the laser. DISCLOSURE OF INVENTION

An objective of the present invention is to provide a medical probe assembly suitable for use in surgery and/or diagnostic applications, such as MIS and/or MID which probe assembly has a very small diameter which enables it to be inserted into and through small diameter lumens (channels) in MIS/MID instruments, such as an endoscope and which probe assembly simultaneously may project a structured light forming a light pattern which in image plan has a high contrast light intensity distribution.

In an embodiment it is an objective to provide a medical probe assembly with a narrow diameter probe head for MIS and/or MID applications and which probe assembly is capable of projecting a structured light forming a light pattern which in image plan has a high contrast light intensity distribution comprising a plurality of light features adapted for machine reading and/or computer vision. This and other objects have been solved by the invention or embodiments thereof as defined in the claims or as described herein below.

It has been found that the invention or embodiments thereof have a number of additional advantages, which will be clear to the skilled person from the following description. It has been found that the medical probe assembly of the invention which has a very narrow probe head diameter may project a structured light forming a light pattern which in image plan has a very high contrast light intensity distribution. Due to the simple and effective structure of the probe assembly, the probe can be held at a narrow diameter of 2 mm or less, which enables the probe assembly to be inserted through very narrow lumens of MIS/MID instruments.

Although probes emitting structured light have been known for years, the prior art probes have either been rather large and in many situations not suitable for use for being inserted through very narrow lumens of MIS/MID instruments. Further, it has also been a problem to provide small probes with high pattern contrast. The present invention provides an attractive medical probe assembly which is very small, have a high pattern contrast and at the same time can be produced at relatively low cost and therefore is highly attractive for use in surgery and/or diagnostics.

The medical probe assembly comprises a rigid probe head, a light source and an optical fiber. The optical fiber is optically connected to receive light from the light source and the optical fiber is coupled to the probe head for delivering light to the probe head.

The light source comprises a laser diode, preferably a semiconductor laser diode. In principle, any laser diode emitting a laser light of a desired high quality may be applied. In principle, the laser source may have any size since the laser source may be arranged with a relative long distance to the probe head. However, in practice it is desired that the laser source is not too large. A relatively small laser source may e.g. be built in or fixed to a robot operator and or built into or mounted to an MIS/MID instrument.

Examples of suitable laser sources include a Fabry-Perot laser (FP) diode, a Vertical-Cavity Surface Emission Laser (VCSEL) diode or a Distributed

Feedback (DFB) laser diode. For optically coupling, the light emitted from the laser diode into the fiber it is desired that the laser source is configured for emitting a symmetrical beam. Alternatively, where the emitted laser beam is elliptical and/or astigmatic the laser source may comprise reshaping optics, such as a cylinder lens, a spherical lens or other kind of reshaping lens. The laser source advantageously comprises a focusing lens adapted to focusing the beam emitted from the laser diode into the core of the optical fiber.

Whereas laser diodes have been applied in tools for minimally invasive surgery, heretofore it has not been possible to provide a narrow band light source using a very small probe. WO2015/116951 discloses a miniature medical probe capable of emitting structured light, however, a requirement for providing this structured light is the use of a broad band light source and the only structuring provided is a spectral structuring referred to as 'spectrally encoded endoscopy' or SEE. The insight of the inventors leading to the present invention provides a large step in the art, making it possible to provide a miniature medical probe configured for emitting intensity structured light with a very high accuracy and contract, and which has been found to be very useful in minimally invasive surgery and diagnostics wherein reflection of the structured light from target area(s) has a very high resolution and with a very high contrast suitable for machine reading.

The optical fiber of the medical probe assembly is optically coupled to deliver the light to the probe head. This is ensured by providing the optical fiber such that it comprises a light output end section with an output facet wherein the light output end is coupled to the probe head.

It has been found that the probe head of the medical probe assembly may have a maximal probe head dimension perpendicular to the probe length of up to about 3, preferably up to about 2 mm or even smaller.

The probe head comprises a beam collimating arrangement and a

patterngenerating projector. The beam collimating arrangement is arranged for receiving the light from the optical fiber and for delivering the received light in the form of beam expanded and collimated light to the pattern generating projector.

The pattern generating projector comprises a diffractive optic element (DOE) configured for structuring and emitting via a distal end of the probe head the received light to form a structured light beam with a light intensity distribution forming a light pattern in an image plan. The term "image plan" is determined to be a plan orthogonal to the optical axis (center axis) of the structured light beam and arranged at a distance of the distal end of the probe head which is within ordinary operation distance e.g. up to 30 cm, such as from 0.5 cm to about 20 cm. The term "body cavity" is herein used to denote any gas and/or liquid filled cavity within a mamma! body. The cavity may be a natural cavity or it may be an artificial cavity or a combination, such as a minimally invasive surgery cavity, which has been filled with a fluid (in particular gas) to reach a desired size. The cavity may be a natural cavity, which optionally has been enlarged or expanded by being filled with a fluid. For example the body cavity may be formed as an expansion of an artificial space e.g. adjacent to a muscle and access is made to form the artificial space by a suitable incision.

The term 'target surface site' or merely "target site' or "target surface" is/are used to mean a surface of a body cavity onto which the structured light beam is projected to form a light pattern.

The terms "distal" and "proximal" should be interpreted in relation to the orientation of the optical transmitter device or any other device used in connection with minimally invasive surgery.

The phrase "real time" is herein used to mean the time required by the computer to receive and process optionally changing data optionally in combination with other data, such as predetermined data, reference data, estimated data which may be non-real time data such as constant data or data changing with a frequency of above 1 minute to return the real time information to the operator. "Real time" may include a short delay, such as up to 5 seconds, preferably within 1 second, more preferably within 0.1 second of an occurrence.

The term "operator" is used to designate a human operator (human surgeon) or a robotic operator i.e. a robot programmed to perform a minimally invasive diagnostic or surgical procedure on a patient. The term "operator" also includes a combined human and robotic operator, such as a robotic assisted human surgeon.

The term "access port" means a port into a body cavity provided by a cannula inserted into an incision through the mammal skin and through which cannula an instrument may be inserted. The term "penetration hole" means a hole through the mammal skin without any cannula.

The phrase "rigid probe head" means that the probe head should be rigid at ordinary use e.g. at 20 - 42 °C. The purpose of making the probe head rigid is to ensure that the alignment of the optical elements within the probe head is maintained as desired during use of the medical probe assembly.

The term "cannula" means herein a hollow tool adapted for being inserted into an incision to provide an access port as defined above.

Often the surface of the minimally invasive surgery cavity is much curved. The term "target area" of the surface of the minimally invasive surgery cavity is herein used to designate an area which the surgeon has focus on, e.g. for diagnostic purpose and/or for surgical/interventional purpose.

The term "skin" is herein used to designate the skin of a mammal. As used herein the skin may include additional tissue, which is or is to be penetrated by the penetrator tip. The term "light intensity" means herein a radiometric quantity, measured in watts per meter squared (W/m²) or mW/pm². The terms "power of light" and "light intensity" are used interchangeably unless otherwise specified or clear from the context.

The phrases" machine reading", "machine read out" and "robot read out" are used to mean that the light is digitally read out and interpreted by a machine. The phrase "computer vision" means that the light is digitally read out and displayed for interpretation by the operator. It should be emphasized that the term "comprises/comprising" when used herein is to be interpreted as an open term, i.e. it should be taken to specify the presence of specifically stated feature(s), such as element(s), unit(s), integer(s), step(s) component(s) and combination(s) thereof, but does not preclude the presence or addition of one or more other stated features.

Throughout the description or claims, the singular encompasses the plural unless otherwise specified or required by the context.

The terms "core" and "core region" are used interchangeably and the terms "cladding" and "cladding region" are used interchangeably. The "an embodiment" should be interpreted to include examples of the invention comprising the feature(s) of the mentioned embodiment.

The term "about" is generally used to include what is within measurement uncertainties. When used in ranges the term "about" should herein be taken to mean that what is within measurement uncertainties is included in the range.

The term "substantially" should herein be taken to mean that ordinary product variances and tolerances are comprised. All features of the invention and embodiments of the invention as described herein, including ranges and preferred ranges, may be combined in various ways within the scope of the invention, unless there are specific reasons not to combine such features.

The laser diode advantageously has a relative narrow bandwidth, which has been found to provide an intensity structured light of high quality, resulting in a pattern in image plan with very high contrast.

Advantageously the laser diode is configured for generating a laser light with a maximal bandwidth of up to about 10 nm, such as up to about 5 nm, such as up to about 1 nm or preferably even less bandwidth. The laser light bandwidth is determined as the full width at half-maximum, (FWHM). Advantageously the laser diode is configured for generating a single wavelength laser light.

A single-frequency laser (sometimes called a single-wavelength laser) is a laser, which operates on a single resonator mode, so that it emits quasi- monochromatic radiation with a very small linewidth and low phase noise. In an embodiment the laser diode is configured for generating the single- wavelength laser light with a linewidth of less than about 10 GHz, such as less than about 10 KHz, such as less than 500 Hz, such as less than 100 Hz. The linewidth is determined as FWHM and at a measurement time of 1 s. In an embodiment the light delivered to the probe head has a linewidth and/or a bandwidth of up to about 0.5 nm, such as up to about 0.1 nm (FWHM).

In an embodiment the wavelength filter may be arranged to wavelength filter the light prior to reaching the beam collimating arrangement. The wavelength filter may be a separate wavelength filter, such as a pin hole filter or it may be an integrated part of the optical fiber, e.g. provided by the transmission bandwidth of the optical fiber.

The laser diode may be a wavelength tunable laser diode, such as a temperature tunable laser diode. For controlling the operation wavelength of the laser diode the light source may advantageously comprise a temperature control arrangement.

The wavelength(s), bandwidth and linewidth referred to herein are

determined at 25 °C unless otherwise specified.

It has been found that the power output of the laser diode need not be very high in order to obtain an intensity structured light beam with a sufficient power so that the reflection thereof from a target surface can be sufficient to deduct the curvature of the target surface. Where the light pattern reflected from the target surfaces is adapted for machine reading, the power of the laser diode output and thereby the structured light may be even lower. Where the pattern reflected from the target surfaces is adapted for being read out for computer vision it may be desired to apply a higher power, however, to avoid undesired heating of the target surface or the area(s) near the target surface the applied power should advantageously not be too high.

As suitable laser diode preferably has a power output of from about 5 mW to about 2 W. Preferably the power at the fiber output end is from about 2 mW to about 500 mW, such as from about 5 mW to about 100 mW, such as from about 10 mW to about 50 mW, such as from about 15 mW to about 30 mW.

The power may advantageously be adjustable by a user or automatically e.g. according to a preprogrammed algorithm or according to a distance to a closest surface within the body cavity. A short time of higher power may for certain operation be advantageous, and further a temporarily higher power of the laser diode may be applied for preheating the probe head or elements thereof such as the DOE.

The laser diode may in principle have any center wavelength and/or peak wavelength, depending on its use. In an embodiment the laser diode has a center wavelength and/or peak wavelength in the interval from about 370 nm to about 15 pm, such as from about 400 nm to about 2 pm, such as from about 425 nm to about 900 nm, preferably in the range from about 450 nm to about 700 nm, preferably in the range from about 500 nm to about 650 nm.

In an embodiment the laser diode has a center wave and/or peak wavelength in the infrared interval from about 700 nm to about 1 mm, such as up to about 100 pm, such as in the Near-infrared interval from about 700 nm to about 3 pm or in the Mid-infrared interval from about 3 pm to about 50 pm.

In an embodiment the laser diode has a center wave and/or peak wavelength in the UV interval from about 157 nm to about 370 nm, such as from about 200 nm to about 350 nm. The center wavelength is determined at 25 °C FWMH unless otherwise specified.

The optical fiber is selected in dependence of the light source and the wavelength(s) to be transmitted to the probe head. For most applications, it is suitable to apply a step index fiber. However, other types of optical fibers may be applied, such as microstructored fibers and/or hollow core fibers.

In an embodiment the optical fiber has a core diameter of from about 4 pm to about 20 pm, such as at least about 8 pm, such as at least about 10 pm, such as at least about 12 pm. Generally, it is desired that the core is relatively large, however, not too large to allow propagation of too many modes as further explained below.

The preferred fiber is a silica glass fiber, optionally doped with one or more refractive index modifying dopants such as fluoride, Germanium, alumina, phosphorous, and boron. However, silica glass has a high attenuation for wavelengths about 2.6 pm and where the center wavelength and/or peak wavelength is relatively high it may be desired to use other glass materials such as fluoride glass (such as zirconium fluoride (ZrF₄) and/or indium fluoride (InF3)) and/or of chalcogenide glass (such as sulfides, selenides or tellurides e.g. of arsenic (As) or germanium (Ge)).

In an embodiment the optical fiber is a polymer step index fiber.

As indicated above it is desired that the laser diode should have a relatively high beam quality and include only few modes.

Advantageously the laser light delivered from the optical fiber to the probe head has a low degree of diffraction. Preferably the laser light delivered from the optical fiber has a M² quality factor of up to 5, such as up to about 2, such as up to about 1.5, such as up to about 1.2, preferably the laser light delivered to the probe head has Gaussian beam shape. The M2 factor, also called beam quality factor or beam propagation factor, is a common measure of a laser beam. According to ISO Standard 11146, it is defined as the beam parameter product divided by λ/ n, the latter being the beam parameter product for a diffraction-limited Gaussian beam with the same wavelength. In other words, the half-angle beam divergence is i¾_™

where wO is the beam radius at the beam waist and λ the wavelength. A diffraction-limited beam (TEMoo) has an M2 factor of 1, and is a Gaussian beam. Smaller values of M² are physically not possible. It is preferred that the optical fiber is a single mode fiber or a few mode fiber at the operating wavelength, such as a few mode fiber guiding up to 20 linearly polarized modes (LP modes), such as up to 10 LP modes, such as up to 6 LP modes, preferably the optical fiber is single mode. In an embodiment the laser diode is single mode. There is the common distinction between single-mode fibers, supporting only one guided mode per polarization direction, and multimode fibers, supporting more than one guided mode. For multimode fibers supporting only a relatively small number of guided modes such as up to 20 it is common to use the phrase "a few mode optical fiber". Preferably the laser diode is a single mode laser diode and the optical fiber has a normalized frequency V of less than 2.405 for at least one transmission wavelength, wherein V is determined by the formula (I)

where a is the core radius, λ is the transmission wavelength in vacuum, ni is the maximum refractive index of the core, r 2 is the refractive index or average refractive index of the cladding.

The operation wavelength is determined as the center wavelength at 25 °C. Unless otherwise specified the characteristics of the laser source and the laser light are determined at 25 °C.

An example of suitable laser diodes includes the single mode visible light laser diodes marketed by Osram Opto Semiconductors, e.g. the laser diodes based on InGaN or GaN. In an embodiment the laser diode is a PL520 Green single mode LD.

The probe head advantageously comprises a housing encasing at least the collimating arrangement and the pattern generating projector. The probe head is advantageously of a rigid material, such as metal material, e.g.

stainless steel and/or such as a rigid polymer, e.g. polystyrene,

polycarbonate, polypropylene and mixtures containing one or more of these. Other material suitable for the housing includes ceramics and glass. Where the probe head is integrated within an instrument, the housing may form part of the instrument.

As indicated above, a purpose of the rigid housing of the probe head is to ensure proper and stable alignment between the optical elements encased in the probe head. However, the housing preferably additionally ensures a smooth and low friction surface. To ensure this the outer surface of the housing may be coated with a low friction material and/or a hydrophilic coating, such as a silicone polyvinyl alcohol (PVA) containing coating and/or a poly ethylene oxide (PEO) coating. Further, the housing may advantageously serve the purpose of protecting the encased elements.

In an embodiment the probe housing defines the probe head length, i.e. the housing preferably encases all the elements of the probe head. In an embodiment the probe head length extends from a proximal end opposite to the distal end and the optical fiber advantageously is coupled to the probe head via its proximal end. In an embodiment the probe head has a uniform cross sectional periphery along at least about 90 % of its length and optional length parts, which do not have the uniform cross sectional periphery have a narrower periphery, preferably the probe head has a uniform cross sectional periphery from up to about 5 mm from its proximal end to at least about 2 mm from its proximal end. For example the probe head may have a narrower periphery at its proximal end. In an embodiment the probe head has a uniform cross sectional periphery along its entire length from its distal end to its proximal end.

For some applications it is desired that probe head has a curvilinear cross sectional periphery, such as round or oval. Thereby the probe head has no sharp edges, which accidently could cause damage to tissue during use. In another embodiment the probe head has an angular cross sectional periphery, such as a square or hexagonal. Thereby the probe head may be adapted for use to be inserted into a lumen of a specific MIS/MID instrument where the lumen has a shape corresponding to the shape of the probe head.

Advantageously the probe head has a maximal probe head dimension perpendicular to the probe length of up to about 1.9 mm, such as up to about 1.8 mm, such as up to about 1.7 mm, such as up to about 1.6 mm, such as up to about 1.5 mm, such as up to about 1.4 mm.

The beam collimating arrangement ensures that the beam delivered from the optical fiber is expanded to a sufficient size and thereafter collimated to be transmitted further to the DOE. It has been found that where the light delivered to the DOE has a relatively large diameter and at the same time is collimated, a high quality intensity structured light can be obtained. Advantageously the beam collimating arrangement is an on-axis beam expanding and collimating element, i.e. an element that does not require a periphery larger than the periphery of the DOE.

An on-axis element is an element that is maintaining the optical axis of the light beam. I.e. the on-axis beam expanding element has a constant optical axis from its input aperture to its output aperture.

In an embodiment the beam collimating arrangement comprises a Keplerian beam expander lens arrangement or a Galilean beam expander lens arrangement, preferably the lens arrangement is hermetically sealed in a beam expander housing, preferably the beam expander housing being vacuumed.

In a preferred embodiment the beam collimating arrangement comprises a gradient index (GRIN) lens, such as a GRIN lens having a cylindrical shape with a length of at least about 1 mm, such as between 1.5 and 4 mm, preferably having a pitch of about 0.25 or about 0.5 and a numerical aperture (NA) of about 0.5 or more.

Gradient Index (GRIN) lenses have a radially varying index of refraction that causes an optical ray to follow a sinusoidal propagation path through the lens. The GRIN lenses have typically been developed and applied for coupling the output of diode lasers into fibers, focusing laser light onto a detector, or for collimating laser light in general. In the projector probe, the GRIN lens is applied for expanding the light beam from the optical fiber.

Thus, in order to ensure a desired degree of expansion the beam expanding lens arrangement advantageously comprises a GRIN lens having NA of about 0.5 or more. The GRIN lens advantageously has a cylindrical shape with a length of at least about 1 mm, such as between 1.5 and 4 mm. The GRIN lens advantageously has a pitch of about 0.25 or about 0.5. By using a GRIN lens, the expansion of the light beam from the optical fiber to the DOE may be controlled and at the same time the high quality of the beam may be maintained as the beam propagates. Where the beam from the optical fiber has been slightly deflected and/or aberrations along the beam edge have formed or been increased, the GRIN lens may compensate for such deflections and/or aberrations.

Where the beam collimating arrangement comprises a Keplerian beam expander lens arrangement or a Galilean beam expander lens arrangement, such deflections and/or aberrations may also be compensated for e.g. by applying additional optical elements such as a distance glass/polymer rod and/or a plano-convex lens as further described below.

Such deflections and/or aberrations may e.g. be caused by the fiber facet. In order to prevent back reflections at the fiber end facet, it is preferred to cut the fiber facet to be non-orthogonal to the optical axis. This may cause spherical aberrations and/or deflections in particular where the light beam travels in free space before reaching the beam collimating arrangement.

Thus, for reducing spherical aberrations and/or deflections it is desired that the fiber end facet is positioned very closely to the beam collimating arrangement such as within a few mm, e.g. 5 mm. This will be described further below.

It is preferred that the light delivered to the beam collimating arrangement has an essentially plane wave front.

Advantageously the beam collimating arrangement has a maximal beam collimating arrangement diameter of up to the maximal diameter of the probe head, preferably up to 2 mm less than the maximal diameter of the probe head, such as up to about 1.8 mm, such as of up to about 1.7 mm, such as of up to about 1.6 mm, such as of up to about 1.5 mm, such as of up to about 1.4 mm, such as of up to about 1.3 mm, such as of up to about 1.2 mm, such as of up to about 1.1 mm, such as of up to about 1 mm, such as of up to about 0.8 mm.

To ensure that a high quality intensity structured light is shaped the beam collimating arrangement is advantageously adapted for expanding the light beam received from the optical fiber to a beam diameter of at least about 0.4 mm, such as at least about 0.6 mm, such as at least about 0.8 mm, such as at least about 1 mm, such as at least about 1.2 mm, such as at least about 1.4 mm, such as at least about 1.6 mm.

The beam diameter is determined according to the D4o (D4Sigma) method which is defined as 4 times the standard deviation of the energy distribution evaluated separately in the X and Y transverse directions over the beam intensity profile.

It is preferred that the beam diameter expansion from the exit of the fiber facet and to the exit of the beam collimating arrangement is at least a 10 times expansion, i.e. the beam diameter at the beam collimating arrangement exit is at least 10 times larger than the beam diameter at the fiber end facet. Preferably the beam diameter expansion from the exit of the fiber facet and to the exit of the beam collimating arrangement is from 20 times to 60 times, such as from about 30 times to 50 times of the diameter at the end facet.

In an embodiment the beam expansion may be partly a free space expansion, meaning that the beam travels a relatively short distance in free space from the fiber end facet to the beam collimating arrangement. However, to ensure that the beam reaching the DOE has a desired high quality practically free of deflections and/or aberrations it is preferred that the major part of the beam expansion is a controlled beam expansion by the beam collimating

arrangement. Preferably at least about 80 %, such as at least about 90 %, such as at least about 95% of the beam expansion from the exit of the fiber end facet to the exit of the beam collimating arrangement is a controlled beam expansion caused by the beam collimating arrangement. The beam collimating arrangement may for example comprise a 10X expander or higher i.e. the beam entering the beam collimating arrangement is expanded 10 times or more at its exit of the beam collimating arrangement. In an embodiment the beam collimating arrangement comprises a 25X expander or higher, such as a 50X expander or higher such as a 75X expander or higher.

Generally, it is desired that the rigid probe head is not too long, in particular where the medical probe assembly is adapted for use in relatively small cavities, since this may render the medical probe assembly inflexible and difficult to handle. Where the medical probe assembly is adapted for use in large cavities or long cavities e.g. for endoscopic examinations in stomach, duodenum, colon, or rectum, the rigid probe head may be longer, but again not too long. Most of the length of the probe head is caused by the length of the beam collimating arrangement, which in most embodiments is the longest element encased in the probe head housing. Thus, it is desired to ensure that the beam collimating arrangement is relatively short while still sufficiently long to ensure a desired beam expansion and collimation of the beam.

Advantageously the beam collimating arrangement has a length of maximum 5 cm, preferably of about 2 cm or less, such as of about 1.5 cm or less, such as of about 1 cm or less, such as of about 8 mm or even less.

The probe head advantageously has a length of up to about 50 cm, such as up to about 10 cm, such as up to about 5 cm, such as up to about 4 cm.

Generally it is desired that the probe head is relatively short as described above, such as up to about 3 cm, such as up to about 2.5 cm, such as up to about 2 cm, such as up to about 1.8 cm, such as up to about 1.6 cm, such as up to about 1.4 cm, such as up to about 1.2 cm.

Advantageously the DOE has a maximum diameter of up to the maximal diameter of the probe head, preferably up to 2 mm less than the maximal diameter of the probe head, such as up to about 1.8 mm, such as of up to about 1.7 mm, such as of up to about 1.6 mm, such as of up to about 1.5 mm, such as of up to about 1.4 mm, such as of up to about 1.3 mm, such as of up to about 1.2 mm, such as of up to about 1.1 mm, such as of up to about 1 mm, such as of up to about 0.8 mm. For optimal exploitation of the DOE and to obtain a high contrast pattern it is desired that the diameter of the beam collimating arrangement and the diameter of the DOE are about equal, such as within 2 mm or less in difference.

The length of the DOE (often referred to as the DOE thickness) is

advantageously relatively short, such as up to a few mm, such as up to about 2 mm, such as up about 1 mm, such as from about 0.1 to about 0.9 mm.

The DOE is configured for structuring the received light to form the light pattern in image plan to have an intensity distribution comprising high intensity area(s) and dark area(s) adjacent to the high intensity area(s). The high intensity area(s) has a higher light intensity per unit area as determined in image plan than the dark area(s). It has been found that due to the structure of the medical probe assembly it has now been ensured that the contrast between high intensity area(s) and dark area(s) may be very sharp and which makes it possible to read and interpret - even by machine reading - reflection of the structured light from target surfaces. Thus, the dark area(s) advantageously has only a very low intensity or none at all. Advantageously at least the major part of the dark area(s) has no light intensity or has a light intensity per unit area which is less than about 5 % of the light intensity of adjacent high intensity area(s), such as less than about 3 %, such as less than about 1 %. Thus, the structure of the medical probe assembly ensures that the light beam that reaches the DOE has an advantageous large beam diameter and a high beam quality while simultaneously the maximum cross sectional dimension or diameter is relative narrow.

The dark area(s) of the light pattern is determined as areas adjacent to the high intensity area(s) and include areas between high intensity area(s). The light intensity of the dark area(s) is preferably determined as the light intensity in the vicinity of the high intensity area(s).

The intensity is determined as intensity per unit area as determined in an image plan. Preferably the intensity is determined in an image plan within a distance of the distal end of the probe head of from 1 to 20 cm, preferably about 5 cm.

Advantageously the dark areas are substantially free of light rays projected from the DOE.

Also thanks to the invention the light intensity of the high intensity area(s) may be substantially uniform which is a very advantageous property, because variations of light intensities, in particularly unstructured variations and/or random variations, may lead to error in particular using machine reading.

In an embodiment the light intensity of the high intensity area(s) varies with less than about 25 % relative to the highest light intensity, such as less than about 10 %, such as less than about 5 %.

In an embodiment the light intensity of the high intensity area(s) differs in two or more intensity levels with at least about 5 %, such as at least about 10 %, such as at least about 20 % difference in intensity based on the highest intensity. Thereby the pattern in image plan may be structured to have different sections with different high intensity area(s). This property may for example provide additional information about the orientation of the light pattern.

The light pattern in image plan may comprise a symmetrical or an

asymmetrical intensity light pattern. By providing the medical probe assembly and especially the DOE of the medical probe assembly, such that the light pattern in image plan is not fully rotational symmetrical, the interpretation e.g. by machine reading may include orientation of the light pattern and features thereof. In an embodiment the light pattern in image plan is at most four fold rotational symmetrical, such as at most two fold rotational symmetrical.

Preferably the light pattern comprises a plurality of light dots, an arch shape, ring or semi-ring shaped lines, a plurality of angled lines, a coded structured light configuration or any combinations thereof. In an embodiment the pattern comprises a grid of lines, a crosshatched pattern optionally comprising substantially parallel lines.

In an embodiment the light pattern in image plan comprises a plurality of light features, each being represented by a local light fraction of the light pattern having an optically detectable attribute. Preferably each light feature comprises a local and characteristic light fraction of the light pattern.

Advantageously the light pattern in image plan comprises a plurality of light features having geometrical attributes, such as the features with geometrical attributes disclosed in co-pending patent application DK PA 2017 70430 filed 1 June 2017.

In an embodiment each of the light features independently of each other comprise a light fraction comprising two or more crossing lines, v-shaped lines, a single dot, a group of dots, a corner section, a pair of parallel lines, a circle or any combinations thereof. Preferably each of the light fractions comprise at least one of a location attribute and an orientation attribute and preferably at least some of the features comprise both a location attribute and an orientation attribute. The location attribute is an attribute of the light feature, which codes for a location in the light pattern e.g. relative to another location in the pattern. The orientation attribute is an attribute of the light feature, which codes for an orientation of the light feature in respect of the orientation of the light pattern.

To ensure an effective coupling of the optical fiber to the probe head, the light output end section of the optical fiber may advantageously be mounted in a ferrule, such as the ferrules generally known and on market. The ferrule is mounted to the probe head for delivering the light to the beam collimating arrangement. The ferrule may e.g. be mounted within the probe head housing, e.g. by a mechanical mount or by glue or solder, e.g. a

biocompatible epoxy. The ferrule may advantageously comprise an orientation indication, such as a color mark, a flange or a flat side, which indication indicates the rotational orientation of the fiber. This may in particular be advantageous where the fiber end facet is not orthogonal to the optical axis of the optical fiber.

Thereby the orientation of the fiber facet may be positioned with a desired orientation relative to the beam collimating arrangement. Further, the probe head housing may comprise an inner shape securing the ferrule is aligned with a desired orientation.

Advantageously the optical fiber facet has a flat surface with a non-orthogonal angle relative to the fiber axis. Thereby risk of back reflection of light into the laser is reduced or avoided. Advantageously the fiber facet has an angle to the fiber optical axis of from about 75 to 85 degrees, such as about 82 degrees.

In an embodiment the fiber facet is coated with an anti-reflex coating such as a coating comprising S1O2 and/or Si3N₄. In an embodiment the light output end section of the optical fiber is mounted to the probe head such that the end facet is butt coupled to the beam collimating arrangement. In this embodiment the fiber facet may be

orthogonal to the optical axis of the optical fiber and the input side of the beam collimating arrangement is flat with same orthogonal orientation or the fiber facet has an angle to the fiber optical axis of less than 90 degrees as described above and the beam collimating arrangement has an input facet end arranged to be mated to the fiber facet i.e. with the corresponding angle.

However, very often for simple alignment the fiber end facet will be arranged with a short distance to the beam collimating arrangement. To ensure that the light beam emitted from the fiber end is only travelling a very short distance in free space, it is desired that the distance between the fiber facet and the beam collimating arrangement is very short, thereby deflection(s) and/or spherical aberrations may be held at a low level which can be corrected by the beam collimating arrangement as described above.

In an embodiment the light output end section of the optical fiber is mounted to the probe head to provide a gap between the fiber facet and the beam collimating arrangement. The gap preferably is less than 1 cm, such as less than 5 mm, such as less than 2 mm, such as less than 1 mm, such as less than 0.5 mm, such as less than 0.1 mm.

In an embodiment the probe head further comprises a distance rod arranged between the fiber facet and the beam collimating arrangement. The distance rod is advantageously of glass or polymer and is substantially transparent at least for the center wavelength and/or peak wavelength of the light from the light source. Advantageously the distance rod is of homogenous glass or polymer. The distance rod may preferably have a refractive index equal to or higher than the core of the optical fiber.

In an embodiment the light output end section of the optical fiber is mounted to the probe head to provide a distance between the fiber facet and the beam collimating arrangement and the distance glass rod is arranged to fill out at least 80 % of the distance. The distance glass preferably is mated to at least one of the fiber facet and the beam collimating arrangement input facet. The distance rod allows the light beam from the optical fiber facet to diverge to expand the beam diameter, however, the expanding of the beam diameter in the distance rod may be more controlled than in free space and thereby possibly resulting deflection(s) and/or spherical aberrations may therefore be less than where the light beam travels in free space. The optical fiber may advantageously be fixed to the light source by a permanent mount or wherein the optical fiber is connected to the light source by a releasable mount.

Thereby the light source can be applied for different probe heads emitting different structured light. Further, it is simpler to clean and sterilize the probe head.

In an embodiment the optical fiber is permanently fixed to the light source. This provides a simple coupling between the light source and the optical fiber.

In an embodiment the beam collimating arrangement is butt coupled to the DOE. The beam collimating arrangement and the DOE may be fused or glued or they may be mechanically held in position by being individually mounted in the probe head housing.

In an embodiment the beam collimating arrangement and the DOE are mounted in the probe head to provide a gap there between. The gap between the beam collimating arrangement and the DOE preferably is less than 1 cm, such as less than 5 mm, such as less than 2 mm, such as less than 1 mm, such as less than 0.5 mm, such as less than 0.1 mm. Where the gap between the beam collimating arrangement and the DOE becomes too large, the collimated light from the beam collimating arrangement may be slightly focused, because it in practice is difficult or even impossible to ensure parallel rays over long distances. Thus, the distance should advantageously be as short as possible.

To ensure mechanical protection of the DOE it is generally desired that the probe head comprises a cover, such as a protecting cover in front of the DOE. The protection cover is preferably of glass or polymer. In an embodiment the cover is a lens. The cover may preferably have an anti-reflex coating on the side facing the DOE. The anti-reflex coating may for example be a coating comprising S1O2 and/or Si3N₄. Advantageously the protection cover is substantially transparent at least for the center wavelength and/or peak wavelength of the light from the light source. In an embodiment the cover absorbs less than 5 % of the power of the structured light from the DOE. The cover preferably comprises an antifouling coating/film and/or an anti-fog coating/film, such as the coating or film disclosed in WO2014197749 and/or US20160251525.

In an embodiment the probe head comprises a heating element arranged for heating at least one of the DOE and a cover for the DOE. The heating arrangement preferably comprises a light absorbing heating arrangement and/or an electrical heating element, such as a micro coil electrical heating element. In an embodiment the heating element is arranged for heating the housing to thereby indirectly heat the DOE and/or the cover. The heating element may e.g. be integrated with the housing e.g. in the form of heating threads incorporated into the material of the housing. In an embodiment the heating arrangement comprises a light absorbing heating arrangement integrated with the DOE and/or the cover for the DOE, wherein at least one of the DOE and the cover is configured for absorbing at least about 1 % of the light delivered to the DOE, such as at least about 5 power %, such as at least about 10 power %, such as at least about 20 power %, of the light delivered to the DOE.

In an embodiment the light source is tunable to a preheating position, in which preheating position the light source has a higher output power than when adapted for use in surgery and/or diagnostics and/or in which preheating position the light source has a different wavelength or wavelength range than when adapted for use in surgery and/or diagnostics and wherein the DOE and/or the cover preferably absorbs more than 20 power % of the different wavelength or wavelength range relative to the light delivered to the DOE. Where the DOE is adapted to absorb a portion of the light, the major part of the absorption preferably takes place in the most distal part of the DOE, such as in a thin distal layer of e.g. 0.5 mm or less, such as about 0.2 mm or less.

The medical probe assembly may comprise an additional light source which is connectable to the optical fiber for delivering light with a higher output power than the laser diode and or a different wavelength or wavelength range than the laser diode and wherein the DOE and/or the cover preferably absorbs more than 20 power % of the different wavelength or wavelength range relative to the light delivered to the DOE. In an embodiment at least one of the DOE and the cover comprises a glass, such as silica, which is doped by ion, such as rare earth ions and/or comprises OH groups. OH groups have peak absorption around 1390 nm, 1897 nm and 2210 nm. OD groups have a peak absorption around 1240 nm. The glass may e.g. comprise about 100 ppm or more, such as about 250 ppm or more of OH/D2 groups.

Suitable doping ions include rare earth ions such as erbium (Er),

neodymium (Nd), terbium (Tb), thulium (Tm), ytterbium (Yb) and yttrium (Y). The glass may advantageous comprise at least a surface layer of doped glass, preferably having a concentration of at least about 100 ppm, such as at least about 200 ppm.

The probe head advantageously comprises a housing hermetically encasing at least the beam collimating arrangement and the DOE. In an embodiment the housing hermetically encases the beam collimating arrangement and the DOE and a cover for the DOE forms part of the housing. The hermetically encasing may e.g. be provided by closing the housing using epoxy.

Advantageously the probe head comprises an antifouling and/or anti-fog coating or film at its distal output end such as the anti-fog coating/film disclosed in WO2014197749 and/or US20160251525. The medical probe assembly preferably comprises a maneuvering arm connected to the probe head, preferably at its proximal end. The

maneuvering arm may be a rigid arm or a bendable arm. In an embodiment the maneuvering arm is an articulated arm such as an articulated robotic arm for mechanical, motor and/or robot maneuvering. Thereby the movements of the probe head may be controlled with a very high and accurate precision. The optical fiber may be incorporated into and pass along the maneuvering arm. In an embodiment the maneuvering arm forms part of a robot and the light source in integrated into the robot. The medical probe assembly is preferably provided such that at least the probe head is adapted for sterilization.

In an embodiment the probe head can withstand a sterilization procedure comprising chemical and/or gas sterilization, such as sterilization comprising exposing the probe head to one or more of ethylene oxide, formaldehyde gas hydrogen peroxide (liquid, gas or plasma), ozone gas and/or a solution comprising one or more of peracetic acid, glutaraldehyde, and formaldehyde.

Thus, in an embodiment the probe head can withstand a sterilization procedure comprising exposure to steam at at least 110 °C, preferably 120 °C for at least about 10 minutes, preferably for at least about 15 minutes. The material of the probe head and in particular the housing and the protection cover if any is selected such that it may withstand at least one of the sterilization methods.

In an embodiment the probe head is made from polymer, glass and/or ceramic, preferably at least the beam collimating arrangement and the DOE are of glass and/or polymer, and preferably the housing is of polymer, glass, metal or ceramic. In an embodiment the housing is of steel, such as stainless steel. The fiber may e.g. be a glass optical fiber or a polymer fiber comprising a core and a cladding and optionally coated with a reinforcement coating, such as a polymer coating, a carbon coating, a ceramic coating and/or a metal coating. Further, the optical fiber may comprise a jacket for further mechanical protection.

The invention also includes a minimally invasive surgical instrument comprising a medical probe assembly as described above.

The medical probe assembly may in an embodiment form an integrated part of the minimally invasive surgical instrument. In an embodiment the minimally invasive surgical instrument comprises a lumen containing at least the probe head of the medical probe assembly. The outer periphery of the probe head is advantageously adapted to correspond to an inner periphery of the lumen such that the probe head may be displaced within and along the length of the lumen. In an embodiment the probe head is adapted to be passed fully through the lumen.

The surgical instrument may e.g. be a laparoscopic instrument, an

arthroscopic instrument, a thoracoscopic instrument, a gastroscopic instrument, a colonoscopic instrument, a laryngoscopy instrument, a broncoscopic instrument, a cytoscopic instrument, an endoscopic sinus instrument, a neuroendoscopic instrument, a gastrocscopic instrument or a combination thereof.

In an embodiment the surgical instrument is an endoscope, such as an endoscope for diagnostic examination of a patient body cavity.

In an embodiment the surgical instrument comprises a surgical tool. The surgical tool is preferably adapted to perform a surgical intervention of a surgery target site. The surgical tool preferably is selected from a grasper, a suture grasper, a stapler, forceps, a dissector, scissors, suction instrument, clamp instrument, electrode, curette, ablators, scalpels, a laser knife, a penetrator, a cannula and a biopsy and retractor instrument or any

combinations thereof. In an embodiment the tool is adapted for withdrawing a biopsy by optical means i.e. an optical biopsy instrument.

All features of the inventions and embodiments of the invention as described herein including ranges and preferred ranges may be combined in various ways within the scope of the invention, unless there are specific reasons not to combine such features.

Brief description of preferred embodiments and elements of the invention

The above and/or additional objects, features and advantages of the present invention will be further elucidated by the following illustrative and non- limiting description of embodiments of the present invention, with reference to the appended drawings.

The figures are schematic and are not drawn to scale and may be simplified for clarity. Throughout, the same reference numerals are used for identical or corresponding parts.

Fig. 1 is a schematic side view of an embodiment of the medical probe assembly of the invention.

Fig. 2 is a schematic side view of a variation of the medical probe assembly of Fig. 1.

Fig. 3 is a schematic, cross sectional side view of a first example of a probe head.

Fig. 4 is a schematic, cross sectional side view of a second example of a probe head. Fig.5 is a schematic, cross sectional side view of a third example of a probe head. Fig. 6 is a schematic exploded view of an optical fiber suitable for the medical probe assembly.

Fig. 7 is a schematic side view of a GRIN lens suitable for forming the beam collimating arrangement. Fig. 8a is a schematic, cross sectional side view of a fourth example of a probe head.

Fig. 8b is a schematic, cross sectional side view of a fifth example of a probe head.

Figs. 9a, 9b and 9c illustrate the periphery of 3 different examples of the probe head.

Figs. 10a and 10b illustrate cross sectional views of the probe housing.

Fig.11 illustrates the outer shape of an example of a probe head.

Fig. 12a illustrates a line light feature with a poor intensity contrast.

Fig. 12b illustrates a dot light feature with a poor intensity contrast. Fig. 12c is a plot of the intensity as a function over the line width or dot diameter of the line and dot light features of figures 12a and 12b.

Fig. 13a illustrates a line light feature with a high intensity contrast.

Fig. 13b illustrates a dot light feature with a high intensity contrast.

Fig. 13c is a plot of the intensity as a function over the line width or dot diameter of the line and dot light features of figures 13a and 13b.

Fig. 14a is a perspective view of an embodiment of a minimally invasive surgical instrument of the invention comprising a grasper tool.

Fig. 14b is a perspective view of an embodiment of a minimally invasive surgical instrument of the invention comprising a hook tool. Fig. 14b is a perspective view of an embodiment of a minimally invasive surgical instrument of the invention comprising a scissors tool.

Fig. 15 is a schematic and perspective view of an embodiment of a minimally invasive surgical instrument in the form of a scope. The medical probe assembly shown in figure 1 comprises a light source 1, a rigid probe head 2 and an optical fiber 3 arranged for guiding light from the light source 1 to the probe head 2. The light source comprises a not shown laser diode as described above. The probe head 2 has a distal end D and a proximal end P and a length L there between. The length may be as described above. The probe head 2 has a maximal probe head dimension MD perpendicular to said probe length L of up to about 2 mm and advantageously less.

As illustrated the probe head 2 is configured for modulating the light received from the optical fiber 3 to a structured light beam 4 with a light intensity distribution forming a light pattern 5 in image plan.

The medical probe assembly shown in figure 2 comprises a light source 11, a rigid probe head 12 and an optical fiber 13 arranged for guiding light from the light source 11 to the probe head 12. The probe head 12 is configured for modulating the light received from the optical fiber 13 to a structured light beam 14 with a light intensity distribution forming a light pattern 15 in image plan. The medical probe assembly comprises a maneuvering arm 16 connected to the proximal end of the probe head 12. The maneuvering arm is an articulated arm such as an articulated robotic arm for mechanical, motor and/or robot maneuvering. In the shown embodiment the optical fiber 13 is held outside the

maneuvering arm 16. In a variation where the maneuvering arm 16 is connected to or forms part of a robot, the light source may be integrated with or positioned in the robot and the optical fiber 13 may be incorporated into the maneuvering arm 16 to thereby form a snake robot. Figure 3 shows an example of a rigid probe head of an embodiment of the medical probe assembly of the invention together with the output end section of the optical fiber 23. The probe head comprises a housing 22 encasing a beam collimating arrangement 27 and a DOE 21. The probe head further comprises a cover 28, such as a cover lens, which may form part of the housing 22. The housing 22 further comprises a proximal end wall 22a to thereby hermetically encase the beam collimating arrangement 27 and the DOE 21.

The optical fiber end section 23 passes through the end wall 22a and is directly butt coupled to the beam collimating arrangement 27. In the shown embodiment, the fiber facet 23a is orthogonal to the optical axis. In a variation the facet 23a has an angle less than 90 degrees - e.g. about 82 degrees to the optical axis and the input facet 27a has a corresponding angle to the optical axis to ensure a full mating between the facet 23a and the beam collimating arrangement input facet 27a.

The beam collimating arrangement 27 and the DOE 21 are also butt coupled such that the collimated light beam from the beam collimating arrangement 27 is directly fed into the DOE 21 without any free space propagating.

As indicated with the dotted lines 29 the light fed to the beam collimating arrangement 27 is beam expanded and collimated and delivered to the DOE 21. The DOE is positioned at a short distance from the cover 28 to provide a gap G between the DOE 21 and the cover 28. The surface of the cover 28 facing the DOE advantageously comprises an anti-reflex coating. As the structured light from the DOE propagates in the fee space in the gap G, the structured light beam starts to diverge and this continues as the light passes the cover. Advantageously the cover has no optical effect on the passing structured light.

Figure 4 shows a second example of a rigid probe head of an embodiment of the medical probe assembly of the invention together with the output end section of the optical fiber 33. The probe head comprises a housing 32 encasing a beam collimating arrangement 37 and a DOE 31. The probe head further comprises a cover 38, such as a cover lens, which may form part of the housing 32. The housing 32 further comprises a proximal end wall 32a to thereby hermetically encase the beam collimating arrangement 37 and the DOE 31.

The optical fiber end section 33 passes through the end wall 32a and is fixed inside the housing 32 via a ferrule 33b. The fiber end facet 33a has a non- orthogonal angle to the optical axis e.g. about 82 degrees relative to the optical axis. Thereby risk of back reflection of light into fiber and the laser is reduced or avoided.

As mentioned above this non-orthogonal fiber end facet 33a may cause spherical aberrations and/or deflections as the light travels in free space in the gap Gl between the fiber facet 33a and the beam collimating

arrangement 37. As indicated with the dotted lines 39, the light been is expanding as it passes from the fiber facet 33a to the beam collimating arrangement 37 and at the same time it is deflected slightly downwards due to the orientation of the facet 33a. In the drawing, the gap Gl appears to be relatively large, in practice it is desired to keep the gap relatively small, preferably such that the distance between the fiber facet 33a (i.e. the edge of the fiber facet 33a closest to the beam collimating arrangement 37) and the beam collimating arrangement 37 is less than 5 mm.

A desired rotational orientation of the fiber facet may be obtained by providing the ferrule 33b with an orientation indicator as described above. The fiber end section 33 is held mechanically in the ferrule 33b. The ferrule may for example be mounted to the housing 32 by a mechanical mount or by clue or solder.

The beam collimating arrangement 37 is advantageously a GRIN lens and as indicated with the dotted lines 37, the light beam is slightly deflected as it reaches the input facet 37a of the beam collimating arrangement 37. As the light propagates through the beam collimating arrangement 37, the beam is further expanded and corrected for the deflection and optional spherical aberrations. At the distal end of the beam collimating arrangement 37 the light beam is collimated and delivered to the DOE 31 which it butt coupled to the beam collimating arrangement 37, such that the collimated light beam from the beam collimating arrangement 37 is directly fed into the DOE 31 without any free space propagating. The DOE is structuring the light beam and emitting the structured light via the distal end D of the probe head such that the light passes through the cover 38. The surface of the cover 38 facing the DOE advantageously comprises an anti-reflex coating

As the structured light from the DOE propagates in the fee space in the gap G2 the structured light beam starts to diverge and this continues as the light passes the cover. Advantageously the cover has no optical effect on the passing structured light. In an embodiment the cover absorbs some of the light for heating the cover as described above.

In a variation the probe head does not have a cover or the DOE acts as a cover.

Figure 5 shows a third example of a rigid probe head of an embodiment of the medical probe assembly of the invention together with the output end section of the optical fiber 43. The probe head comprises a housing 42 encasing a beam collimating arrangement 47 and a DOE 41. The probe head further comprises a cover 48, such as a cover lens, which may form part of the housing 42. The housing 42 further comprises a proximal end wall 42a to thereby hermetically encase the beam collimating arrangement 47 and the DOE 41.

The optical fiber end section 43 passes through the end wall 32a and is fixed inside the housing 42 e.g. via a not shown ferrule. The fiber end facet 33a has a non-orthogonal angle to the optical axis e.g. about 82 degrees relative to the optical axis. Thereby risk of back reflection of light into fiber and the laser is reduced or avoided.

The fiber facet 43 is arranged with a distance to the beam collimating arrangement 47 such that the light beam from the optical fiber end section 43 travels in free space in the gap Gl between the fiber facet 43a and the beam collimating arrangement 47.

The beam collimating arrangement 47, e.g. a GRIN lens corrects deflection and optional spherical aberration as the light beam propagates through the beam collimating arrangement 47. At the distal end of the beam collimating arrangement 47 the light beam is collimated and delivered to the DOE 41 via a gap G2 between the beam collimating arrangement 47 and the DOE 41. As described above it is desired that the gap G2 is not too large, e.g. 5 mm or less, since in practice it is difficult or even impossible to maintain the light collimated over long distances. The DOE is structuring the light beam and emitting the structured light via the distal end D of the probe head such that the light passes through the cover 48.

As the structured light from the DOE propagates in the fee space in the gap G3, the structured light beam starts to diverge and this continues as the light passes the cover.

Figure 6 shows a step index fiber suitable for use in an embodiment of the medical probe assembly of the invention. The step index fiber comprises a core 51 having a first refractive index and a cladding 52 surrounding the core

51. The cladding 52 has a lower refractive index than the core 51. For reinforcement, the optical fiber comprises a coating applied onto the cladding

52. The coating 53 may for example be a polymer coating, a carbon coating or a metallic coating. Finally, the optical fiber comprises a jacket 54 for mechanical protection. The jacket 54 may e.g. be of polymer such as polyethylene, polypropylene or mixtures comprising one or more of these. Figure 7 shows a GRIN lens suitable for forming the beam collimating arrangement of an embodiment of the medical probe assembly. The GRIN lens has an input facet 61 - also referred to as an input aperture - and an output facet 62 - also referred to as an output aperture. The GRIN lens has a length L. The GRIN lens has a radially varying index of refraction which changes along the length L of the GRIN lens to thereby provide that a light beam entering the GRIN lens via its input facet 61 is expanded and corrected for optional deflection and/or aberrations and thereafter collimated to be emitted as a collimated light beam at the output end facet 62 of the GRIN lens.

Figure 8a shows a fourth example of a probe head of an embodiment of the medical probe assembly and a fiber end section 73.

The probe head comprises a housing 72 encasing a beam collimating arrangement 77 and a DOE 71. The probe head further comprises a cover 78. The optical fiber end section 73 is arranged to deliver a light beam to the beam collimating arrangement 77, the beam collimating arrangement 77 is expanding and collimating the light beam and transmitting the collimated light beam to the DOE 71. The DOE is structuring the light beam and emitting the structured light out of the probe head via the cover 78. The beam collimating arrangement 77 is a Keplerian beam expander comprising a first positive lens 77a and a second - usually positive)

collimating lens 77c arranged at a distance to each other corresponding to the sum of their focal length. The first lens is often referred to as the objective lens and the second lens is called the image lens. The first negative lens 77a and the second collimating lens 77c are fixed in respective ends of a beam collimating housing 77d to fully encase the space 77b between the first negative lens 77a and the second collimating lens 77c. In the Keplerian beam expander 79 the beam is focused to a point between the two lenses. This creates a spot of concentrated energy within the beam expander space 79c, which may heat air, if any within the system and deflect light from its optical path. Advantageously the space 77b between the first lens 77a and the second collimating lens 77c is vacuumed thereby reducing the risk of a local heat spot. Figure 8b shows a fifth example of a probe head of an embodiment of the medical probe assembly and a fiber end section 73. The probe head shown in figure 8b differs from the probe head shown in figure 8a in that the beam collimating arrangement 79 is a Galilean beam expander.

The Galilean beam expander 79 comprises a first focusing (negative) lens 79a and a second (positive)collimating lens 79c arranged at a distance to each other corresponding to the sum of their focal length. I is desired that the space 79b between the two lenses 79a, 79b is vacuumed.

The first focusing lens 79a and the second collimating lens 79c are fixed in respective ends of a beam collimating housing 79d to fully encase the space 79b between the first focusing lens 79a and the second collimating lens 79c and as mentioned the space 79b is advantageously vacuumed. The use of a negative lens allows the distance between the two lenses to be much shorter than in a Keplerian beam expander.

Figure 9a shows an example of a periphery of a probe head housing i.e. a cross sectional view perpendicular to the center axis of the probe head. In this example the probe head is circular.

Figure 9b shows another example of a periphery of a probe head housing where the probe head is square.

Figure 9c shows a further example of a periphery of a probe head housing where the probe head is octagonal.

Figure 10a shows an example of a probe head housing seen in a cross- sectional view. The housing has housing wall 80, a distal end D and a proximal end P and has a uniform cross sectional outer periphery along its entire length. Adjacent to the distal end D the housing has an inwardly projecting edge 81 for mounting a DOE or a cover for the DOE.

Figure 10b shows another example of a probe head housing seen in a cross- sectional view. The housing has housing wall 83, a distal end D and a proximal end P and has a uniform cross sectional outer periphery along its entire length. Adjacent to the distal end D the housing has a first carving 85 and a second carving 84 in its inside wall. The first carving 85 and the second carving 84 are advantageously adapted for mounting respectively a cover and a DOE. The housing inner wall may have additional carvings and/or protrusions for mounting for example the beam collimating arrangement and the ferrule.

Figure 11 shows the outer shape of an example of a probe head. The probe head has a distal end D and a proximal end P and a maximal outer dimension along its length from the distal end D to the proximal end P. In a first length section LI closer to the distal end D, the probe head has a uniform periphery and maximal outer dimension. In a second length section L2 closer to the proximal end P, the probe head outer dimension is gradually narrowing towards the proximal end P.

Figure 12a illustrates a line light feature with a poor intensity contrast. In figure 13a a corresponding line light feature with a high intensity contrast is illustrated. In the same way figure 12b illustrates a dot light feature with a poor intensity contrast and figure 13b illustrates a corresponding dot light feature with a high intensity contrast.

Figure 12c is a plot of the intensity as a function over the line width or dot diameter of the line and dot light features of figures 12a and 12b. It can be seen that the intensity profile is very broad and with a relative low intensity peak. This profile indicates that the edges of the light features are blurred and may be difficult to read in particular using machine reading. Figure 12c is a plot of the intensity as a function over the line width or dot diameter of the line and dot light features of figures 13a and 13b. It can be seen that the intensity profile is very narrow and with a relative high intensity peak. This profile indicates that the edges of the light features are sharp and suitable for machine reading.

Figures 14a, 14b and 14c show 3 different examples of minimally invasive surgical instrument of embodiments of the invention.

The minimally invasive surgical instrument shown in figure 14a comprises a grasper tool 91 and has a lumen containing a probe head 90 of a medical probe assembly of an embodiment of the invention.

The minimally invasive surgical instrument shown in figure 14b comprises a hook tool 95 and has a lumen containing a probe head 95 of a medical probe assembly of an embodiment of the invention.

The minimally invasive surgical instrument shown in figure 14c comprises a scissors tool 93 and has a lumen containing a probe head 92 of a medical probe assembly of an embodiment of the invention.

Figure 15 shows an embodiment of a minimally invasive surgical instrument in the form of a scope. The scope comprises an elongate scope body 100 comprising a number of lumens for various tools and/or instruments. A first center lumen 102 is adapted for inserting a camera or alternatively a camera may be fixed therein. A second edge lumen 103 is adapted for inserting an illumination element or alternatively an illumination element may be fixed therein. A third edge lumen 101 is adapted for inserting a probe head of a medical probe assembly of an embodiment of the invention. Further scope of applicability of the present invention will become apparent from the description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

Claims

PATENT CLAIMS

1. A medical probe assembly for surgical and/or diagnostic use, the probe assembly comprises a rigid probe head, a light source and an optical fiber operatively connected to receive light from said light source and coupled to said probe head for delivering light to the probe head, said light source comprises a laser diode, said optical fiber comprises a light output end section with an output facet, said light output end being coupled to said probe head, said probe head has a length and a maximal probe head dimension

perpendicular to said probe length of up to about 3 mm, such as up to about 2 mm, and comprises a beam collimating arrangement and a pattern generating projector, said beam collimating arrangement is arranged for receiving said light from said optical fiber and for delivering beam expanded and collimated light to said pattern generating projector, said pattern generating projector comprises a diffractive optic element (DOE) configured for structuring and emitting via a distal end of the probe head the received light to form a structured light beam with a light intensity distribution forming a light pattern an in image plan.

2. The medical probe assembly of claim 1, wherein the laser diode is configured for generating a laser light with a maximal bandwidth of up to about 10 nm, such as up to about 5 nm, such as up to about 1 nm.

3. The medical probe assembly of claim 1 or claim 2, wherein the laser diode is configured for generating a single wavelength laser light.

4. The medical probe assembly of claim 3, wherein the single-wavelength laser light generated by the laser diode has a linewidth of less than about 10 GHz, such as less than about 10 KHz, such as less than 500 Hz, such as less than 100 Hz.

5. The medical probe assembly of any one of the preceding claims, wherein the light delivered to the probe head has a linewidth and/or a bandwidth of up to about 0.5 nm, such as up to about 0.1 nm (FWHM).

6. The medical probe assembly of any one of the preceding claims, wherein the laser diode is a semiconductor laser, preferably selected from a Fabry-Perot laser (FP) diode, a Vertical-Cavity Surface Emission Laser (VCSEL) diodes or a Distributed Feedback (DFB) laser diode.

7. The medical probe assembly of any one of the preceding claims, wherein the laser diode is temperature tunable, preferably the light source comprises a temperature control arrangement.

8. The medical probe assembly of any one of the preceding claims, wherein the laser diode has a power output of from about 5 mW to about 2 W, preferably the power at the fiber output end is from about 2 mW to about 500 mW, such as from about 5 mW to about 100 mW, such as from about 10 mW to about 50 mW, such as from about 15 mW to about 30 mW.

9. The medical probe assembly of any one of the preceding claims, wherein the laser diode has a center wavelength and/or peak wavelength in the interval from about 370 nm to about 15 pm, such as from about 400 nm to about 2 pm, such as from about 425 nm to about 900 nm, preferably in the range from about 450 nm to about 700 nm, preferably in the range from about 500 nm to about 650 nm.

10. The medical probe assembly of any one of the preceding claims, wherein the laser diode has a center wavelength and/or peak wavelength in the infrared interval from about 700 nm to about 1 mm, such as up to about 100 pm, such as in the Near-infrared interval from about 700 nm to about 3 pm or in the Mid-infrared interval from about 3 pm to about 50 pm.

11. The medical probe assembly of any one of the preceding claims, wherein the optical fiber is a step index fiber, having a core diameter of from about 4 pm to about 20 pm, such as at least about 8 pm, such as at least about 10 pm, such as at least about 12 pm.

12. The medical probe assembly of any one of the preceding claims, wherein the optical fiber is of silica glass, fluoride glass (such as zirconium fluoride (ZrF₄) and/or indium fluoride (lnF3)) and/or of chalcogenide glass (such as sulfides, selenides or tellurides e.g. of arsenic (As) or germanium (Ge)).

13. The medical probe assembly of any one of the preceding claims, wherein the light delivered from the optical fiber to the probe head has a M² quality factor of up to 5, such as up to about 2, such as up to about 1.5, such as up to about 1.2, preferably the laser light delivered to the probe head has Gaussian beam shape.

14. The medical probe assembly of any one of the preceding claims, wherein the optical fiber is a single mode fiber or a few mode fiber at the operating wavelength, such as a few mode fiber guiding up to 20 linearly polarized modes (LP modes), such as up to 10 LP modes, such as up to 6 LP modes, preferably the optical fiber is single mode.

15. The medical probe assembly of any one of the preceding claims, wherein the probe head comprises a housing encasing said collimating arrangement and said pattern generating projector, said probe housing preferably defines the probe head length.

16. The medical probe assembly of any one of the preceding claims, wherein the probe head length extends from a proximal end opposite to the distal end and wherein the probe head has a uniform cross sectional periphery along at least about 90 % of its length and optional length parts which do not have the uniform cross sectional periphery have a narrower periphery, preferably the probe head has a uniform cross sectional periphery from up to about 5 mm from its proximal end to at least about 2 mm from its proximal end, preferably the probe head has a uniform cross sectional periphery along its entire length.

17. The medical probe assembly of any one of the preceding claims, wherein the probe head has a curvilinear cross sectional periphery, preferably the cross sectional periphery is round or oval and the maximal dimension is the maximal diameter.

18. The medical probe assembly of any one of the preceding claims, wherein the probe head has an angular cross sectional periphery, such as a square or hexagonal.

19. The medical probe assembly of any one of the preceding claims, wherein the probe head has a maximal probe head dimension perpendicular to said probe length of up to about 1.9 mm, such as up to about 1.8 mm, such as up to about 1.7 mm, such as up to about 1.6 mm, such as up to about 1.5 mm, such as up to about 1.4 mm.

20. The medical probe assembly of any one of the preceding claims, wherein the beam collimating arrangement is an on-axis beam expanding and collimating element.

21. The medical probe assembly of any one of the preceding claims, wherein the beam collimating arrangement comprises a Keplerian beam expander lens arrangement or a Galilean beam expander lens arrangement, preferably the lens arrangement is hermetically sealed in a beam expander housing, preferably the beam expander housing being vacuumed.

22. The medical probe assembly of any one of the preceding claims, wherein the beam collimating arrangement comprises a gradient index (GRIN) lens, such as a GRIN lens having a cylindrical shape with a length of at least about 1 mm, such as between 1.5 and 4 mm, preferably having a pitch of about 0.25 or about 0.5 and a numerical aperture (NA) of about 0.5 or more.

23. The medical probe assembly of any one of the preceding claims, wherein the beam collimating arrangement has a maximal beam collimating arrangement diameter of up to about 1.8 mm, such as of up to about 1.7 mm, such as of up to about 1.6 mm, such as of up to about 1.5 mm, such as of up to about 1.4 mm, such as of up to about 1.3 mm, such as of up to about 1.2 mm, such as of up to about 1.1 mm, such as of up to about 1 mm, such as of up to about 0.8 mm.

24. The medical probe assembly of any one of the preceding claims, wherein the beam collimating arrangement is adapted for expanding the light beam received from the optical fiber to a beam diameter of at least about 0.4 mm, such as at least about 0.6 mm, such as at least about 0.8 mm, such as at least about 1 mm, such as at least about 1.2 mm, such as at least about 1.4 mm, such as at least about 1.6 mm.

25. The medical probe assembly of any one of the preceding claims, wherein the beam collimating arrangement comprises a 10X expander or higher, such as a 25X expander or higher, such as a 50X expander or higher such as a 75X expander or higher.

26. The medical probe assembly of any one of the preceding claims, wherein the beam collimating arrangement has a length of about 5 cm or less, such as of about 2 cm or less, such as of about 1.5 cm or less, such as of about 1 cm or less, such as of about 8 mm or less.

27. The medical probe assembly of any one of the preceding claims, wherein the light delivered to the beam collimating arrangement has an essentially plane wave front.

28. The medical probe assembly of any one of the preceding claims, wherein the DOE has a maximum diameter of up to about 1.8 mm, such as of up to about 1.7 mm, such as of up to about 1.6 mm, such as of up to about 1.5 mm, such as of up to about 1.4 mm, such as of up to about 1.3 mm, such as of up to about 1.2 mm, such as of up to about 1.1 mm, such as of up to about 1 mm, such as of up to about 0.8 mm.

29. The medical probe assembly of any one of the preceding claims, wherein the DOE is configured for structuring the received light to form said light pattern in image plan to have an intensity distribution comprising high intensity area(s) and dark area(s)adjacent to the high intensity area(s), wherein the high intensity area(s) has a higher light intensity per unit area as determined in image plan than the dark area(s), preferably the major part of dark area(s) has no light intensity or has a light intensity per unit area which is less than about 5 % of the light intensity of adjacent high intensity area(s), such as less than about 3 %, such as less than about 1 %.

30. The medical probe assembly of claim 29, wherein the dark areas is substantially free of light rays projected from the DOE.

31. The medical probe assembly of claim 29 or claim 30, wherein the light intensity of the high intensity area(s) is substantially uniform.

32. The medical probe assembly of claim 29 or claim 30, wherein the light intensity of the high intensity area(s) varies with less than about 25 % relative to the highest light intensity, such as less than about 10 %, such as less than about 5 %.

33. The medical probe assembly of any one of the preceding claims, wherein the light pattern in image plan comprises a symmetrical or an asymmetrical intensity light pattern, preferably the light pattern comprises a plurality of light dots, an arch shape, ring or semi-ring shaped lines, a plurality of angled lines, a coded structured light configuration or any combinations thereof, preferably the pattern comprises a grid of lines, a crosshatched pattern optionally comprising substantially parallel lines.

34. The medical probe assembly of any one of the preceding claims, wherein the light pattern in image plan comprises a plurality of light features, each being represented by a local light fraction of the light pattern having an optically detectable attribute, preferably each light feature comprises a local and characteristic light fraction of the light pattern.

35. The medical probe assembly of claim 34, wherein each of said light features independently of each other comprise a light fraction comprising two or more crossing lines, v-shaped lines, a single dot, a group of dots, a corner section, a pair of parallel lines, a circle or any combinations thereof, preferably each of said light fractions comprise at least one of a location attribute and an orientation attribute.

36. The medical probe assembly of any one of the preceding claims, wherein the rigid probe head has a length of up to about 50 cm, such as up to about 10 cm, such as up to about 5 cm, such as up to about 6 cm, such as up to about 3 cm, such as up to about 2.5 cm, such as up to about 2 cm, such as up to about 1.8 cm, such as up to about 1.6 cm, such as up to about 1.4 cm, such as up to about 1.2 cm.

37. The medical probe assembly of any one of the preceding claims, wherein the light output end section of said optical fiber is mounted in a ferrule, and said ferrule is mounted to said probe head for delivering said light to the beam collimating arrangement, preferably the ferrule is mounted within the probe head housing, e.g. by a mechanical mount or by clue or solder.

38. The medical probe assembly of any one of the preceding claims, wherein the optical fiber facet has a flat surface with a non-orthogonal angle relative to the fiber axis, said fiber facet preferably has an angle of from about 75 to 85 degrees, such as about 82 degrees.

39. The medical probe assembly of any one of the preceding claims, wherein the light output end section of said optical fiber is mounted to said probe head such that the end facet is butt coupled to said beam collimating arrangement, preferably the beam collimating arrangement has an input facet end arranged to be mated to the fiber facet.

40. The medical probe assembly of any one of the preceding claims 1-38, wherein the light output end section of said optical fiber is mounted to said probe head to provide a gap between said fiber facet and said beam collimating arrangement, said gap preferably being less than 1 cm, such as less than 5 mm, such as less than 2 mm, such as less than 1 mm, such as less than 0.5 mm, such as less than 0.1 mm.

41. The medical probe assembly of any one of the preceding claims 1-38, wherein the probe head further comprises a distance rod arranged between said fiber facet and said beam collimating arrangement, said distance rod preferably being of homogenous glass or polymer having a refractive index equal to or higher than the core of the optical fiber.

42. The medical probe of claim 37, wherein the light output end section of said optical fiber is mounted to said probe head to provide a distance between said fiber facet and the beam collimating arrangement and said distance rod is arranged to fill out at least 80 % of the distance, said distance glass preferably being mated to at least one of the fiber facet and the beam collimating arrangement input facet.

43. The medical probe assembly of any one of the preceding claims, wherein the optical fiber is fixed to the light source by a permanent mount or wherein the optical fiber is connected to the light source by a releasable mount.

44. The medical probe assembly of any one of the preceding claims, wherein the beam collimating arrangement is butt coupled to said DOE.

45. The medical probe assembly of any one of the preceding claims, wherein the beam collimating arrangement and the DOE are mounted in the probe head to provide a gap there between, the gap between the beam collimating arrangement and the DOE preferably being less than 1 cm, such as less than 5 mm, such as less than 2 mm, such as less than 1 mm, such as less than 0.5 mm, such as less than 0.1 mm.

46. The medical probe assembly of any one of the preceding claims, wherein said probe head comprises a cover, such as a protecting cover in front of the DOE, said protection cover preferably being of glass or polymer, and preferably said protection cover being substantially transparent at least for the center wavelength and/or peak wavelength of the light from the light source.

47. The medical probe assembly of any one of the preceding claims, wherein said probe head comprises a heating element arranged for heating at least one of the DOE and a cover for the DOE, said heating arrangement preferably comprises a light absorbing heating arrangement and/or an electrical heating element, such as a micro coil electrical heating element.

48. The medical probe assembly of claim 43, wherein said heating arrangement comprises a light absorbing heating arrangement integrated with said DOE and/or said cover for the DOE, wherein at least one of said DOE and said cover is configured for absorbing at least about 1 % of the light delivered to the DOE, such as at least about 5 power %, such as at least about 10 power %, such as at least about 20 power %, of the light delivered to the DOE.

49. The medical probe assembly of claim 47, wherein said light source is tunable to a preheating position, in which preheating position the light source has a higher output power than when adapted for use in surgery and/or diagnostics and/or in which preheating position the light source has a different wavelength or wavelength range than when adapted for use in surgery and/or diagnostics and wherein the DOE and/or the cover preferably absorbs more than 20 power % of the different wavelength or wavelength range relative to the light delivered to the DOE.

50. The medical probe assembly of claim 47, wherein said medical probe assembly comprises an additional light source which is connectable to said optical fiber for delivering light with a higher output power than said laser diode and or a different wavelength or wavelength range than said laser diode and wherein the DOE and/or the cover preferably absorbs more than 20 power % of the different wavelength or wavelength range relative to the light delivered to the DOE.

51. The medical probe assembly of claim 50, wherein at least one of said DOE and said cover comprises a glass, such as silica, which is doped by ion, such as rare earth ions and/or comprises OH groups.

52. The medical probe assembly of any one of the preceding claims, wherein the probe head comprises a housing hermetically encasing from a proximal end to a distal end the beam collimating arrangement the DOE and optionally said cover.

53. The medical probe assembly of any one of the preceding claims, wherein the probe head comprises an anti-fog coating at its distal output end.

54. The medical probe assembly of any one of the preceding claims, wherein the probe head can withstand a sterilization procedure comprising chemical and/or gas sterilization, such as sterilization comprising exposing the probe head to one or more of ethylene oxide, formaldehyde gas hydrogen peroxide (liquid, gas or plasma), ozone gas and/or a solution comprising one or more of peracetic acid, glutaraldehyde, and formaldehyde.

55. The medical probe assembly of any one of the preceding claims, wherein the probe head can withstand a sterilization procedure comprising exposure to steam at at least 110 °C, preferably at 120 °C for at least about 10 minutes, preferably for at least about 15 minutes.

56. The medical probe assembly of any one of the preceding claims, wherein the probe head is made from polymer, glass and/or ceramic, preferably at least the beam collimating arrangement and the DOE are of glass and/or polymer, and preferably the housing is of polymer, glass or ceramic.

57. A minimally invasive surgical instrument comprising a medical probe assembly according to any one of the preceding claims.

58. The minimally invasive surgical instrument of claim 56, wherein said surgical instrument is a laparoscopic instrument, an arthroscopic instrument, a thoracoscopic instrument, a gastroscopic instrument, a colonoscopic instrument, a laryngoscopy instrument, a broncoscopic instrument, a cytoscopic instrument, an endoscopic sinus instrument, a neuroendoscopic instrument, a gastrocscopic instrument or a combination thereof.

59. The minimally invasive surgical instrument of claim 57 or claim 58, wherein said surgical instrument is an endoscope.

60. The minimally invasive surgical instrument of claim 57 or claim 58, wherein said surgical instrument comprises a surgical tool, said surgical tool is preferably adapted to perform a surgical intervention of a surgery target site, said surgical tool preferably is selected from a grasper, a suture grasper, a stapler, forceps, a dissector, scissors, suction instrument, clamp instrument, electrode, curette, ablators, scalpels, a laser knife, , a penetrator, a cannula and a biopsy and retractor instrument or any combinations thereof.