CN103543495B - Image acquisition and in-situ projection optical device - Google Patents

Abstract

The invention discloses an optical device for image collection and in-situ projection, which includes a wavelength division multiplexing module for multiplexing light beams of two different wavelengths into an optical fiber; The beam is collimated; the focusing lens is used to focus the collimated beam; the MEMS scanning mirror is used to reflect the focused beam to the surface of the imaging object; the photoelectric detection module is used to receive the near The infrared light is converted into electrical signals; the imaging and projection control module is used to control the wavelength division multiplexing module to output two beams of different wavelengths according to the electrical signals, and to control the deflection speed of the MEMS scanning mirror. Since the light output by the imaging light source and the projection light source are coupled into the same optical fiber and then collimated for output, the invention ensures that the optical paths of the two are completely overlapped, and a drift-free projection image can be obtained on the surface of the object; and the performance is stable, the volume is small, low cost.

Description

An optical device for image acquisition and in-situ projection

technical field

The invention belongs to the technical field of image detection, and more particularly relates to an optical device for image acquisition and in-situ projection.

Background technique

The visible light band is 390-780nm. When each part of the surface of an object can form a differentiated reflectance for this band of light, it can produce color or grayscale and form an image visible to the human eye. However, there are also many objects whose reflectivity to visible light is not significantly different from each part of the surface, so under the irradiation of visible light, the surface image visible to the human eye cannot be presented. If it is irradiated with light other than the visible light band, differential reflectivity may be produced. However, the presented image cannot be directly observed by the human eye, and can only be detected by various photodetectors.

For example, some people with darker skin color or thicker fat layer, the outline of the veins on the back of the hand is not clearly visible, but when irradiated with near-infrared light, it can produce significantly different reflectivity and form an image, but this image is not human visible to the eye. If the image can be detected by a photodetector in the near-infrared band, and then the detected image data can be used to modulate the visible light and projected onto the back of the hand in situ, then the clear outline of the vein can be observed.

Therefore, for the surface image of an object that cannot be directly observed by the human eye, it is possible to select a wavelength of light (invisible light) to irradiate the object by analyzing the spectral characteristics of the object, and use the corresponding photodetector to collect image information, and then pass another A wavelength of light (visible light) that projects an image onto the surface of an object in situ, the effect of which is equivalent to the surface image of an object directly observed by the human eye.

There are two main types of existing image acquisition and in-situ projection technologies. The first one uses infrared CCD to directly image the surface of the object, and then uses the liquid crystal panel to project the image onto the surface of the object through visible light. The advantages of this technical solution are imaging and The projection speed is fast, but the disadvantage is that the cost is expensive; the second is a scanning imaging system composed of infrared light, scanning mirror, and photodetector, and a scanning projection system is composed of visible light and scanning mirror. The advantage of this technical solution is that the cost is low. The imaging and projection speed is slightly lower, but it can meet the requirements, because of the visual persistence effect of the human eye, as long as the projection speed reaches more than 25 frames per second.

Image acquisition and in-situ projection technology require that the projection optical path and the imaging optical path are completely overlapped. The above two technical solutions both realize the collinear design of the two through the spatial optical path, and use multiple sets of prisms and lenses to adjust the optical path. The optical path structure is complex. , not only the adjustment is troublesome, the error is large, but also it takes up space, so it is difficult to miniaturize. In the above second scheme, as shown in Figure 1, the near-infrared light source 1 emits near-infrared light, which is focused on the surface of the projected object after being restricted by a filter and subsequent lens groups, and then the near-infrared beam is incident on the line scanning mirror , if the surface of the object is positioned by the XY coordinate system, the light beam can be scanned along the X direction by rotating the mirror surface of the line scanning mirror. Then the near-infrared beam is incident on the field scanning mirror, and the mirror surface of the field scanning mirror can be rotated to scan the beam along the Y direction, so that every point on the surface of the object can be scanned. The near-infrared light beam is reflected by the surface of the object, processed by the photodetector, converted into an electrical signal, and input to the control module to control the visible light source 2 to emit visible light, and to stop the photodetection module from working. After the visible light passes through the above optical path, it is finally projected onto the surface of the object for imaging, showing the position of the vein. A line scanning mirror and a field scanning mirror are used to realize two-dimensional scanning imaging and projection. Two scanning mirrors complicate the optical path structure and make it difficult to realize miniaturization design.

Contents of the invention

Aiming at the above defects or improvement needs of the prior art, the present invention provides an optical device for image acquisition and in-situ projection. The technical problems of complex optical path structure and large error in the prior art.

The invention provides an optical device for image acquisition and in-situ projection, including a wavelength division multiplexing module for multiplexing light beams of two different wavelengths into an optical fiber; an optical fiber collimator, through the optical fiber and the optical fiber The wavelength division multiplexing module is connected to collimate the beam output from the optical fiber; the focusing lens is used to focus the collimated beam; the MEMS scanning mirror is used to reflect the focused beam to the imaging object surface; a photoelectric detection module, used to receive the near-infrared light reflected back from the surface of the imaging object and convert it into an electrical signal; and an imaging and projection control module, respectively connected to the wavelength division multiplexing module and the MEMS scanning mirror It is connected with the photoelectric detection module, and is used to control the wavelength division multiplexing module to output light beams of two different wavelengths according to the electrical signal, and to control the deflection speed of the MEMS scanning mirror, and to control the photoelectric detection module at Works with near-infrared light and pauses with visible light.

Furthermore, the wavelength division multiplexing module includes a first semiconductor laser, a second semiconductor laser, a filter and a first optical fiber head; the input control end of the first semiconductor laser is connected to the imaging and projection control module, As an imaging light source, it is used to output a beam of a wavelength (the imaging light source uses near-infrared light); the input control terminal of the second semiconductor laser is connected to the imaging and projection control module, as a projection light source, for output A beam of another wavelength (the projection light source is visible light); beams of two different wavelengths are multiplexed into the same optical fiber through the filter and the first optical fiber head respectively.

Furthermore, the optical fiber collimator includes a second optical fiber head, a collimating lens, and a glass tube arranged coaxially; the glass tube is an annular cylinder with a hollow structure inside, and the second optical fiber head and the The collimating lens is arranged in the glass tube, the second fiber optic head is used to fix the optical fiber, and the glass tube is used to fix the second fiber optic head and the collimating lens.

Furthermore, the collimator lens is a first cylindrical lens, the input surface of the first cylindrical lens is a plane, and the output surface of the first cylindrical lens is a convex spherical surface.

Furthermore, the collimating lens is a second cylindrical lens, the input surface of the second cylindrical lens is a plane, the output surface of the second cylindrical lens is a plane, and the The refractive index gradually decreases along the radial direction according to the law of parabola.

Furthermore, the diameter 2ω _f of the focused spot of the focusing lens, the size 2ω _c of the collimated beam and the focal length f of the focusing lens satisfy the formula λ is the wavelength of near-infrared light or the wavelength of visible light.

Furthermore, the scanning speed of the MEMS scanning mirror is greater than 25 frames per second.

The present invention also provides a medical vein imager, including an optical device for imaging with near-infrared light and then projecting on the object to be measured in situ through visible light, characterized in that the optical device is the above-mentioned optical device.

Since the light output by the imaging light source and the projection light source are coupled into the same optical fiber and then collimated for output, the invention can ensure that the optical paths of the two are completely overlapped, so that a drift-free projection image can be obtained on the object surface. And the wavelength division multiplexing module has the characteristics of stable performance, small size and low cost; the use of two-dimensional MEMS scanning mirror further simplifies the optical path structure and reduces the size of the system)

Description of drawings

Fig. 1 is a schematic structural view of an optical device provided by the prior art;

2 is a schematic diagram of the module structure of an optical device for image acquisition and in-situ projection provided by an embodiment of the present invention;

3 is a schematic structural diagram of a wavelength division multiplexing module in an optical device for image acquisition and in-situ projection provided by an embodiment of the present invention;

Fig. 4 is a schematic structural diagram of a fiber collimator in an optical device for image acquisition and in-situ projection provided by an embodiment of the present invention;

FIG. 5 is a schematic structural diagram of a MEMS scanning mirror in an optical device for image acquisition and in-situ projection provided by an embodiment of the present invention.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not constitute a conflict with each other.

In view of the above, aiming at the deficiencies of the prior art, the present invention proposes a new optical device for image acquisition and in-situ projection by introducing optical fiber and MEMS (Micro-Electro-Mechanical Systems) technology, which can realize The projection optical path and the imaging optical path are precisely overlapped, and have the characteristics of simple structure, small volume and low cost.

The optical device for image acquisition and in-situ projection proposed by the present invention includes a wavelength division multiplexing module 1 , a fiber collimator 2 , a focusing lens 3 , a MEMS scanning mirror 4 , a photoelectric detection module 5 , and an imaging and projection control module 6 . The light output by the wavelength division multiplexing module 1 is output by the optical fiber to the fiber collimator 2, and then the beam passes through the optical path through the focusing lens 3, wherein the center of the fiber collimator 2 and the center of the focusing lens 3 are at the center of the beam, and the MEMS scanning mirror 4 The center is set at the center of the beam. The photoelectric detection module 5 is placed on the beam path reflected by the object surface, and the imaging and projection control module 6 controls the switching off of the two light sources in the wavelength division multiplexing module 1 and the deflection speed of the MEMS scanning mirror 4, and simultaneously controls the photoelectric detection Module 5 works under near-infrared light and suspends work under visible light.

Among them, the wavelength division multiplexing module 1 includes two semiconductor lasers emitting different wavelengths, a filter and an optical fiber head. The two lasers are respectively used as an imaging light source and a projection light source. The beams of different wavelengths emitted by the two pass through the filter. multiplexed into the same fiber. The fiber collimator 2 collimates the light beam output from the fiber. The focusing lens 3 focuses the collimated light beam on the surface of the imaging object. The MEMS scanning mirror 4 reflects the light beam to the surface of the imaging object. The photoelectric detection module 5 receives the near-infrared light reflected from the surface of the imaging object and converts it into an electrical signal, and inputs the electrical signal to the imaging and projection control module 6 through a circuit. The imaging and projection control module 6 respectively controls the switching off of the two semiconductor lasers in the wavelength division multiplexing module 1 and the deflection speed of the MEMS scanning mirror 4 through circuits, and simultaneously controls the photoelectric detection module 5 to work in near-infrared light and pause in visible light Work.

The working principle of the optical device is that first, the imaging light source in the wavelength division multiplexing module 1 is turned on by the imaging and projection control module 6 to emit near-infrared light, and the near-infrared light signal enters the fiber collimator 2 and converts the near-infrared light signal In order to collimate the near-infrared beam, the collimated infrared beam is incident on the focusing lens 3 and then focused on the MEMS scanning mirror 4, and the imaging and projection control module 6 provides voltage to control its deflection speed. After the MEMS scanning mirror 4 reflects and focuses the incident light beam to a certain point on the surface of the imaging object, the near-infrared light beam is reflected again, and the reflected near-infrared light signal is incident on the photoelectric detection module 5, and the photoelectric detection module 5 detects the surface of the imaging object. For reflected light, the intensity of the light signal received by different points on the surface of the imaging object is different to measure the reflectivity of different reflection points, so as to obtain the image gray level of the reflection point, and then fed back to the imaging and projection control module by the photoelectric detection module 5 6 An electrical signal makes the imaging and projection control module 6 control the wavelength division multiplexing module 1 to turn off the near-infrared light source, turn on the projection visible light source to send a visible light signal, and at the same time the imaging and projection module 6 controls the photoelectric detection module 5 Work, pause work when visible light. Then the visible light signal is incident on the fiber collimator 2 to convert the visible light signal into a collimated visible light beam. The collimated visible light beam is incident on the focusing lens 3 and then focused on the MEMS scanning mirror 4 at its focal point. The MEMS scanning mirror 4 projects the incident light beam and Focus to the position of the first reflection on the surface of the imaged object. Through the coordinated control of the imaging and projection control module 6, the MEMS scanning mirror 4 is allowed to perform two-dimensional scanning at a speed greater than 25 frames per second, and the response and switching speed of the photoelectric detection module 5 and the wavelength division multiplexing module 1 are higher than the scanning speed , a stable two-dimensional projection image can be obtained on the surface of the object.

In the embodiment of the present invention, the fiber collimator is composed of a fiber head and a collimating lens. The collimating lens in the fiber collimator can be a C-Lens or a self-focusing lens, and the spot size of the collimated beam depends on the parameters of the lens used. The optical fiber head in the optical fiber collimator and wavelength division multiplexing module uses a capillary to fix the optical fiber so as to be assembled and positioned in the application. The inner diameter of the capillary in the optical fiber head is slightly larger than the outer diameter of the optical fiber, and the outer diameter is designed according to the needs of positioning and assembly. The material of the capillary can be glass or ceramics. The filter in the wavelength division multiplexing module transmits the imaging light wavelength and reflects the projection light wavelength; or reflects the imaging light wavelength and transmits the projection light wavelength. The two lasers in the wavelength division multiplexing module are semiconductor lasers, which have high reliability, low power consumption and are conducive to miniaturization and packaging.

As an embodiment of the present invention, the optical fiber used for coupling output in the wavelength division multiplexing module may be a single-mode optical fiber or a multi-mode optical fiber. The focusing lens is composed of multiple single lenses, which can be designed to eliminate aberrations, and obtain a smaller focusing spot on the surface of the object to ensure the image resolution of imaging and projection. The MEMS scanning mirror can perform two-dimensional scanning along the X-axis and Y-axis. The scanning area depends on the deflection angle of the scanning mirror and the distance between the scanned object and the scanning mirror.

In the embodiment of the present invention, since the light output by the imaging light source and the projection light source are coupled into the same optical fiber and then collimated, the optical paths of the two can be completely overlapped, so that a drift-free projection image can be obtained on the object surface. And the wavelength division multiplexing module has the characteristics of stable performance, small size and low cost. Using a two-dimensional MEMS scanning mirror further simplifies the structure of the optical path and reduces the size of the system.

The main idea of the present invention is to couple the imaging light source and the projection light source into the same optical fiber through wavelength division multiplexing technology, and then output them through the fiber collimator to ensure that the imaging light path and the projection light path are completely coincident in principle; The MEMS scanning mirror replaces the two scanning mirrors of the line scanning mirror and the field scanning mirror in the traditional structure, and realizes the miniaturization design of the whole system.

The main difference between the optical device provided by the embodiment of the present invention and the prior art is that the prior art uses multiple lens groups to change the light beam to achieve the coincidence of the optical paths of the two beams, but the beam has a divergence angle when propagating. Here we use The multi-lens is also to avoid the occurrence of projection distortion caused by the different spot sizes of the final projection on the surface of the object due to the divergence angle of the two beams during the propagation process. At the same time, the scanning method of this solution is to use two scanning mirrors to scan the X direction and the Y direction separately, so the integration level is not high and takes up a lot of space. However, the present invention uses an optical fiber to couple the two light beams together. Even if the light beams have divergence angles during propagation, they are bound in one optical fiber all the time, so it can well ensure that the optical paths of the two light beams coincide. At the same time, the use of a small MEMS scanning mirror can scan the X direction and Y direction at the same time to achieve two-dimensional scanning, and we have designed some structural parameters to make the light spot small when the beam reaches the MEMS scanning mirror, which can be completely reflected by MEMS. In addition, the existing technology spreads the optical path in space, and uses lens groups to perform multiple optical path transformations, which not only takes up space, but also has a poor overlapping effect of the optical paths, resulting in errors. In the present invention, both beams of light are coupled into one optical fiber, so that the optical paths overlap. Moreover, in terms of scanning and projection, the original solution is to use two mirrors (line scanning mirror and field scanning mirror) to scan and project in the X direction and Y direction respectively, so as to achieve two-dimensional scanning. This solution uses a MEMS scanning mirror with a small structure, and uses electrostatic or magnetic attraction to act on the X-axis and Y-axis of the MEMS scanning mirror, so that the MEMS scanning mirror can rotate in both the X and Y directions. Two-dimensional scanning is thereby performed.

In order to further illustrate the optical device provided by the embodiment of the present invention, the present invention will be further described in conjunction with the accompanying drawings:

Referring to accompanying drawing 2, in the specific embodiment of this image acquisition and in-situ imaging optical device, comprise wavelength division multiplexing module 1, fiber collimator 2, focusing lens 3, MEMS scanning mirror 4, photoelectric detection module 5, and imaging And the projection control module 6, wherein the imaging and projection control module 6 can coordinate and control the wavelength division multiplexing module 1, the MEMS scanning mirror 4 and the photoelectric detection module 6, so as to ensure the normal operation of the system.

Referring to accompanying drawing 3, comprise first semiconductor laser 11, the second semiconductor laser 13, filter plate 12 and the first optical fiber head 14 in the wavelength division multiplexing module 1, two lasers are used as imaging light source and projection light source respectively, the two emitted Beams of different wavelengths are multiplexed through the filter 12 and coupled into the same optical fiber. The first semiconductor laser is used as an imaging light source, outputting near-infrared light; the second semiconductor laser is used as a projection light source, outputting visible light; beams of two different wavelengths are respectively multiplexed into the same optical fiber through a filter and the first optical fiber head.

The working principle of the optical device is that first, the imaging light source in the wavelength division multiplexing module 1 is turned on by the imaging and projection control module 6 to emit near-infrared light, and the near-infrared light signal enters the fiber collimator 2 and converts the near-infrared light signal In order to collimate the near-infrared beam, the collimated infrared beam is incident on the focusing lens 3 and then focused on the MEMS scanning mirror 4, and the imaging and projection control module 6 provides voltage to control its deflection speed. After the MEMS scanning mirror 4 reflects and focuses the incident light beam to a certain point on the surface of the imaging object, the near-infrared light beam is reflected again, and the reflected near-infrared light signal is incident on the photoelectric detection module 5, and the photoelectric detection module 5 detects the surface of the imaging object. For reflected light, the intensity of the light signal received by different points on the surface of the imaging object is different to measure the reflectivity of different reflection points, so as to obtain the image gray level of the reflection point, and then fed back to the imaging and projection control module by the photoelectric detection module 5 6 An electrical signal makes the imaging and projection control module 6 control the wavelength division multiplexing module 1 to turn off the near-infrared light source, turn on the projection visible light source to send a visible light signal, and at the same time the imaging and projection module 6 controls the photoelectric detection module 5 Work, pause work when visible light. Then the visible light signal is incident on the fiber collimator 2 to convert the visible light signal into a collimated visible light beam. The collimated visible light beam is incident on the focusing lens 3 and then focused on the MEMS scanning mirror 4 at its focal point. The MEMS scanning mirror 4 projects the incident light beam and Focus to the position of the first reflection on the surface of the imaged object. Through the coordinated control of the imaging and projection control module 6, the MEMS scanning mirror 4 is allowed to perform two-dimensional scanning at a speed greater than 25 frames per second, and the response and switching speed of the photoelectric detection module 5 and the wavelength division multiplexing module 1 are higher than the scanning speed , a stable two-dimensional projection image can be obtained on the surface of the object.

Referring to accompanying drawing 4, fiber collimator 2 is made up of second fiber head 21, collimator lens 22 and glass tube 23, and second fiber head 21, collimator lens 22 and glass tube 23 are coaxially arranged; Glass tube 23 is ring The structure is cylindrical and hollow inside, the second fiber optic head 21 and the collimator lens 22 are arranged in the glass tube 23, and the second fiber optic head 21 is used to fix the fiber optic head and the collimator lens 22. Wherein, the glass tube is an annular cylinder with a hollow inside, and its inner diameter wraps the fiber optic head and the collimating lens, and the fiber optic head is used to fix the fiber optic head and the collimating lens. The fiber head is a capillary glass tube, the fiber is inserted into the inner tube of the fiber head, the fiber head is used to support and fix the fiber, the outer diameter of the fiber is slightly smaller than the inner diameter of the fiber head. The axis of the collimating lens is on the same line as the optical fiber. In general, the glass tube, collimating lens, fiber lens, and optical fiber are coaxial, that is to say, their axes are on the same straight line. The second optical fiber head 21 supports and positions the optical fiber. Its inner diameter is slightly larger than the outer diameter of the optical fiber, and its outer diameter is designed according to assembly requirements. The second optical fiber head 21 is generally made of glass or ceramic materials. The collimating lens 22 can be a C-Lens or a self-focusing lens, as shown in Figure 4(a), the C-Lens is a cylindrical lens, the input and output surfaces are respectively flat and convex spherical, and the spot of the collimated beam The size 2ω _c depends on the light wavelength λ, the mode field diameter 2ω ₀ in the fiber, and the C-Lens parameters: material refractive index n and spherical curvature radius R, as shown in formula (1).

${\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; \&lambda;R</span>}}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; \&pi;</span>}{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

As shown in Figure 4(b), the self-focusing lens is a cylindrical lens with a gradient refractive index. Both surfaces are flat. The refractive index at the lens axis is the highest, and the refractive index gradually decreases along the radial direction according to the parabola law. As shown in formula (2), the spot size 2ω _c of the collimated beam depends on the wavelength λ, the mode field diameter 2ω ₀ in the fiber, and the parameters of the self-focusing lens: the axis position refractive index n ₀ , the refractive index gradient constant And the lens length Z, such as formula (3).

$\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; r</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; no</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>{<span\; class="notranslate">\; (</span>\sqrt{\mathrm{<span\; class="notranslate">\; A</span>}}\mathrm{<span\; class="notranslate">\; r</span>}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

${\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}{\mathrm{<span\; class="notranslate">\; \&pi;</span>}{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}{\mathrm{<span\; class="notranslate">\; no</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}\sqrt{\mathrm{<span\; class="notranslate">\; A</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

The inner diameter of the glass tube 23 is precisely matched with the outer diameter of the second fiber head 21 and the collimator lens 22 to ensure that the second fiber head 21 and the collimator lens 22 are coaxially packaged, so that the collimated beam is output along the axis of the fiber collimator 2 .

By selecting the type of the collimating lens 22 and designing various parameters reasonably, the required collimating spot size can be obtained. The focusing lens 3 is composed of multiple single lenses and designed to eliminate aberrations. The diameter 2ω _f of the final focusing spot depends on the size 2ω _c of the collimated beam and the focal length f of the focusing lens 3, as shown in formula (4).

${\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; \&lambda;\; f</span>}}{\mathrm{<span\; class="notranslate">\; \&pi;</span>}{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; )</span>$

Wherein, λ is the wavelength of near-infrared light or visible light. For near-infrared light and visible light, each has two wavelengths. At this time, ω _c is different due to different wavelengths, so ω _f is also different due to different wavelengths. The focal length f should be a fixed value after calculation, and ω _f is different due to different wavelengths because the human eye's discrimination ability is generally discernible.

Referring to accompanying drawing 5, the mirror surface of MEMS scanning mirror 4 is supported by two frames (X-axis frame and Y-axis frame) and two pairs of deflection axes (X deflection axis and Y deflection axis), driven by electrostatic attraction or electromagnetic attraction, It can be deflected along the two axes of X axis and Y axis, so as to achieve the tilt of the mirror surface, so as to adjust the incident angle of the incident light, so that the exiting direction of the outgoing light is different, so as to scan and project the surface of the imaging object, so as to scan and deflect the beam. The scanning range of the beam on the surface of the object depends on the deflection angle amplitude ±θ _x , ±θ _y of the scanning mirror and the distance L between the object and the scanning mirror, as shown in formula (5).

D _x × D _y = 4Lθ _x × 4Lθ _x (5)

Since the MEMS scanning mirror 4 continuously performs two-dimensional scanning, in order to form a stable projection image on the object surface, its scanning speed is required to be greater than 25 frames per second. During the very short period when the scanning mirror stays at a certain deflection angle, through the imaging and projection control module 6, a series of actions such as turning on the imaging light source, photoelectric detection, turning off the imaging light source, and turning on the projection light source must be completed. And the response and switching speed of the projection control module 6 , the wavelength division multiplexing module 1 , and the photoelectric detection module 5 are higher than the scanning speed of the MEMS scanning mirror 4 .

Since the light output by the imaging light source and the projection light source are coupled into the same optical fiber and then collimated for output, it can be ensured that the optical paths of the two are completely overlapped, and a drift-free projection image can be obtained on the surface of the object, and the wavelength division multiplexing module 1 has Stable performance, small size and low cost. The use of two-dimensional MEMS scanning mirror 4 has the characteristics of small size and large scanning angle, which is conducive to the miniaturization design of the system, and can be applied to some handheld instruments.

A typical application of the image acquisition and in-situ projection optical device is a medical vein imager. For example, for some people with darker skin or thicker fat layer, the outline of the veins on the back of the hand is not clearly visible, and the optical device of the present invention can be used , using near-infrared light to irradiate the image, and then projecting on the back of the hand through visible light in situ, you can observe the clear outline of the vein.

Compared with the prior art, the present invention mainly has two improvements. (1) The optical fiber is used to completely overlap the optical paths of the two beams. The original technology uses multi-lens groups to transform the optical paths of the beams to achieve the overlapping of the two optical paths. The adjustment is complicated and accurate. low, but the present invention uses an optical fiber to couple the two beams of light into this optical fiber, so as to achieve the purpose of optical path overlap, without complicated adjustment, and the two beams are in the same optical fiber. The optical paths overlap, and the accuracy is guaranteed. (2) Use the MEMS scanning mirror to scan. The original plan is to use the line scanning mirror and the field scanning mirror to scan the two orthogonal directions respectively, so as to achieve two-dimensional scanning. However, the MEMS scanning mirror is used in the present invention. The principle is By applying electrostatic or electromagnetic attraction to the two orthogonal axes of the mirror, that is, the X-axis and the Y-axis, the X-axis and the Y-axis can adjust the MEMS scanning mirror in all directions, that is, through a MEMS scanning mirror, the beam can be moved along the object at the same time. The surface is scanned to achieve two-dimensional scanning. At the same time, the MEMS scanning mirror itself has a small structure and can be miniaturized.

It is easy for those skilled in the art to understand that the above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention, All should be included within the protection scope of the present invention.

Claims (7)

1. An optical device for image acquisition and in situ projection, characterized in that it comprises: A wavelength division multiplexing module (1), configured to multiplex light beams of two different wavelengths into an optical fiber; the two light beams of different wavelengths are near-infrared light and visible light respectively; An optical fiber collimator (2), connected to the wavelength division multiplexing module (1) through the optical fiber, is used to collimate the light beam output in the optical fiber; Focusing lens (3), used for focusing the collimated light beam; MEMS scanning mirror (4), used to reflect the focused light beam to the surface of the imaging object; A photoelectric detection module (5), configured to receive the near-infrared light reflected back from the surface of the imaging object and convert it into an electrical signal; and The imaging and projection control module (6) is connected with the wavelength division multiplexing module (1), the MEMS scanning mirror (4) and the photoelectric detection module (5) respectively, and is used to control the The wavelength division multiplexing module (1) outputs light beams of two different wavelengths, and controls the deflection speed of the MEMS scanning mirror (4), and also controls the photoelectric detection module (5) to work in near-infrared light, and in visible light stop working when The wavelength division multiplexing module (1) includes a first semiconductor laser (11), a second semiconductor laser (13), a filter (12) and a first optical fiber head (14); The input control terminal of the first semiconductor laser (11) is connected to the imaging and projection control module (6) as an imaging light source for outputting a light beam of a wavelength; The input control terminal of the second semiconductor laser (13) is connected to the imaging and projection control module (6) as a projection light source for outputting a beam of another wavelength; Light beams of two different wavelengths are multiplexed into the same optical fiber through the filter (12) and the first optical fiber head (14) respectively. 2. optical device as claimed in claim 1, is characterized in that, described optical fiber collimator (2) comprises the second optical fiber head (21) that coaxially arranges, collimator lens (22) and glass tube (23) ; The glass tube (23) is an annular cylinder and an internal hollow structure, the second optical fiber head (21) and the collimating lens (22) are arranged in the glass tube (23), the The second optical fiber head (21) is used for fixing the optical fiber, and the glass tube is used for fixing the second optical fiber head and the collimating lens. 3. The optical device according to claim 2, characterized in that, the collimator lens (22) is a first cylindrical lens, the input surface of the first cylindrical lens is a plane, and the first cylindrical lens The output surface of the lens is convex spherical. 4. The optical device according to claim 2, characterized in that, the collimator lens (22) is a second cylindrical lens, the input surface of the second cylindrical lens is a plane, and the second cylindrical lens The output surface of the lens is a plane, and the refractive index of the second cylindrical lens gradually decreases along the radial direction according to the law of a parabola. 5. The optical device according to any one of claims 1-4, characterized in that, the diameter 2ω _f of the focused spot of the focusing lens (3), the size 2ω _c of the collimated light beam and the focusing lens (3) ) focal length f satisfies the formula λ is the wavelength of near-infrared light or the wavelength of visible light. 6. The optical device according to any one of claims 1-4, wherein the scanning speed of the MEMS scanning mirror is greater than 25 frames per second. 7. A medical vein imager, comprising an optical device for imaging with near-infrared light, and then projecting on the object to be measured in situ through visible light, characterized in that the optical device is the one described in any one of claims 1-4. the optical device described above.