DE10321885A1 - Confocal imaging arrangement has an imaging component with variable diffractive power whose main plane is arranged at least approximately in the focal plane of the test objective - Google Patents

Abstract

Confocal arrangement with a variable refractive power component with a test objective (12), whereby the component (7) has at least a diffractive sub-component. The main plane of the variable diffractive power imaging component (7) is arranged at least approximately in the focal plane of the test objective (12) or in a plane that is optically conjugated with this plane. This plane contains at least approximately the pupil plane of the whole system for the object illumination and imaging. Independent claims are also included for a further two confocal arrangements and three confocal imaging methods.

Description

State of technology

It has been known that through-focus has been used in confocal microscopy since Marvin Minski [see patent specification US 3,013,467 from December 19, 1961] a functional role. Many efforts have already been made to implement through-focusing without mechanically moving parts. HJ Tiziani and H.-M. Uhde in the article Three-dimensional image sensing by chromatic confocal microscopy in Applied Optics, Vol. 33, No. April 1, 1994, pp. 1838 to 1843. In the specialist article Chromatic confocal microscopy with microlenses by HJ Tiziani, R. Achi and RN Krämer in Journal od Modern Optics, 1946, Vol. 43, No. 1, 155-163, for example, diffractive microlenses are used in cooperation with different laser wavelengths for chromatic focusing. When using diffractive microlenses for chromatic focusing, the chromatic longitudinal aberration of the transfer optics also often plays a not insignificant role.

In Scripture DE 196 12 846 A1 additional optics with a defined chromatic longitudinal error are described. It is a chromatic-confocal arrangement with a refractive power-variable additional imaging system with a test lens, whereby the chromatic longitudinal aberration of the confocal arrangement should correspond exactly to that of the additional imaging system. However, this requires zero-error lenses, which are comparatively expensive. In Scripture DE 196 12 846 A1 In particular, however, it is not shown where exactly the main planes of these additional optics have to be in relation to the microscope objective in order to completely avoid undesired, chromatically caused effects and changes in the imaging scale.

in the Technical article "Nontranslational three-dimensional profilometry by chromatic confocal microscopy with dynamically configurable micromirror scanning by S. Cha, P. C. Lin, L. Zhu, P.-Ch. Sun and Y. Feinman in Applied Optics, Vol. 39, No. 16 from June 1, 2000, pp. 2605 to 2613 becomes the possibility demonstrated by means of an imaging level with a diffractive Lens has a chromatic longitudinal aberration to achieve. However, this variable power arrangement also changes the scale of the Image from the object to the camera. This is for the metrological application usually not acceptable. Furthermore, the article "3D Micro-inspection goes DMD "by F. Please, G. Dussler and T. Pfeiffer in the journal Optics and Lasers in Engineering 36 (2001) 155-167 a possibility presented the confocal principle using DMDs to generate controlled Apply light source points in an array. However, here the time for the three-dimensional measurement in the prior art still a few Minutes.

in the Technical article "Twisted nematic liquid-crystal pixelated active lens "by Vincent Laude in Optics Communications from July 15, 1998, pp. 135 to 152, discusses the many possibilities noted by operations in the pupil with electronically controlled Arrays, here LCDs, for example focusing in an imaging system to influence, i.e. to focus. In the work shown the LCD is located in the pupil plane of the imaging system. However changes yourself focusing through these operations in the pupil as well the focal length of the entire imaging system. The unwanted consequence is the change here of the image scale the image with such a focus. Continue to change the directions of the light rays in the field so influenced Illustration, for example when imaging a measurement object a camera. This can be the case, for example, with fast imaging systems with big Pupils in connection with modern cameras with integrated microlens arrays, which is best at least approximately telecentric Need beam path, pose a problem, because in addition to the lateral smearing still the intensity can change in the pixels of the camera when focusing through. These mentioned Properties pose particularly for the high-resolution three-dimensional Measurement technology is an unacceptable limitation, even if a part the influences can still be compensated numerically.

Goal and task the invention

The The aim of the invention is an inexpensive, robust, depth-measuring, confocal sensor to determine the distance, shape and in particular the two- or three-dimensional micro profile of measurement objects, which can possibly also be moved in the measuring process. Furthermore can in a microscopic sample volume to be analyzed by means of a confocal sensor, but also two- or three-dimensional Transparency or reflection profiles of the sample can be determined. In the solution according to the invention must However, it is not always a microscopic beam path act as with confocal arrangements based on the invention also the shape of comparatively large objects optically scanned shall be.

The invention solves the problem of measuring the distance of a surface or the surface of an object optically, very quickly and comparatively precisely using the confocal De method tection, or to scan with a confocal sensor even in a comparatively large depth range, in particular to detect the two- or three-dimensional profile of the surface. However, the two- or three-dimensional transparency or reflectance profile of an object can also be determined with the invention.

description the invention

It it is assumed that with a confocal arrangement with Power-variable, imaging component of the object to be inspected in all cases considered here, a test lens assigned.

The Refractive power generally represents the reciprocal of the focal length of an imaging system and can therefore also be used for diffractive and reflective, imaging components are used.

The test lens assigned to the object can be a microscope lens and serves both for lighting the object surface as well as the image of the same. The test lens can also be used as a lens for the macroscopic image should be formed. Furthermore, in the test lens in a known manner in the beam path of the confocal arrangement be preceded by a tube lens. However, it must be here not a lens that corrects to infinity is. In extreme cases, the tube lens can be confocal in the invention Arrangement is even completely absent. This tube lens can be a monochromatic or in the case of a chromatic-confocal method a spectrally broadband source be arranged upstream of electromagnetic radiation. This source, mostly a light source in the visible spectral range can have a spectral distribution with at least three different spectral ranges. This Areas can in the limit case by three individual wavelengths of a laser light source be shown. On the other hand, the light source can at least approximately designed as a white light emitter his. It is also possible, that the light source itself is sequenced in a known manner wavelength tunable is, for example as a Ti: Sapphir laser. A white light source can also be used in conjunction with a downstream monochromator be formed, whereby the time sequential tuning is possible.

in the Beam path is an in to realize the confocal principle known system arranged the light beam limiting system, preferably with a fixed microlens array an aperture arranged in a subsequent imaging stage. This microlens array generates a number of light source points, preferably at least a single line, preferably in several lines or preferably in an array arrangement. Will instead of a microlens array If only a single microlens is used, only a single one is created Light source point and therefore only a single scanning point. But it can also basically arbitrary figures of light source points are formed.

the Prüfobjektiv is in the direction of light for the lighting is preceded by a variable, imaging component. Viewed laterally, this component should always have the effect of a have individual optical systems, so preferably only one have only one optical axis and therefore usually itself do not represent an array. The refractive power, imaging component has at least approximately in the area of its optical axis a single one or if optical components with a larger center thickness are used are a first and a second main level. Here is this Component preferably centered on the test lens. This refractive power variable, imaging component can also have at least one single diffractive Include subcomponent. The first and second major surfaces of this power variable, imaging component are at least approximately the two main planes of an optical imaging system. These main levels can be at a thin system also at least approximately collapse in a single plane. It is inventive here that one of the main planes or the common main plane of the power variable, imaging component at least approximately in the object facing focal plane of the test lens or arranged in a plane optically conjugate to this focal plane is, this level also also the pupil level of the overall system for object lighting and Representing the object image in the confocal arrangement.

I agree these features described here now lead to a change the refractive power of this refractive power variable, imaging component there is a depth shift of the images generated by the test lens the light source points in the object space results. Here, and that's it Particularly advantageous, the heavy beam remains in the object space its position, at least approximately unchanged. There the focal plane of the test lens facing away from the object may also be the pupil plane the heavy beams in the object space are always at least approximately telecentrically trained. So the image scale remains the confocal arrangement even with a variation in the refractive power of the refractive power variable, imaging component constant.

there is it for this invention completely secondary, whether the change the refractive power of the refractive power variable, imaging component over the Light wavelength changes that System is therefore chromatic, or in another way the refractive power changed this component is, for example, by a predetermined control.

If there is no common main plane of the refractive power, imaging Component there is preferably the other main plane of the power variable, imaging component at least approximately in the focal plane of the tube lens, which is assigned to the test lens. Then advantageously also exists effectively in the area of the light source points a telecentric beam path, since only the telecentric part the beam of light continues to be used. The refractive power, imaging component but can preferably also be as thin accomplished be that at least approximately so there is only one main level and this main level with the two coplanar focal planes of the tube lens and the test lens or in a plane optically conjugate to these focal planes in coincides at a common level.

there can the refractive power variable, imaging component under certain Conditions also have zero refractive power.

First According to the invention, the refractive power of the refractive power variable, imaging component depending on the wavelength of the light change. Then the refractive power variable imaging component is a chromatic one System that uses a light source with multiple light wavelengths becomes. This chromatic, refractive power variable, imaging preferably exists Component from two subcomponents. These preferably exhibit at least approximately medium wavelength in the spectrum of the light source used, at least approximately in magnitude same, but reversed refractive power, so that from a sub-component a light beam is collected and from the is scattered to others. At least one of these is preferably Subcomponents formed chromatically. Both subcomponents can also be used formed with at least partially diffractive microstructures his. However, a diffractive microstructure can also be formed be at least in a spectral range - at least for some selected Light wavelengths - achromatic Has properties. These two diffractive subcomponents are preferred with their diffractive structures directly opposite, are, for example, only at a distance of a few light wavelengths from each other.

So is then this chromatic refractive power variable, imaging component preferably diffractive or at least partially diffractive. It can but also imaging both subcomponents of this refractive power variable Component be formed chromatically. If necessary, here too a formation of the same with opposite chromatic characteristics consist. The second subcomponent can be refractive so as a preferably thin Lens or be formed as a lens group.

Preferably is the refractive power variable, imaging, chromatic component in dependence of the light wavelength So at the same time a focusing one with zero refractive power or one the light beam divergent component. In any case, this component represents such an imaging system with variable refractive power. In addition, this refractive power variable, imaging component preferably rotationally symmetrical. This affects both their geometric shape and their optical function. This component can have an annular active surface, ie an annular pupil surface, for example due to central shading. The refractive power variable is preferably imaging, chromatic component to the optical axis of the test objective centered.

By the circular effective area this component or the subcomponents used for construction can In a confocal setup, lenses are also used that So in the middle on the optical axis, not or not sufficiently are well corrected and thus only have an annular surface in the pupil. The center shading of the test lens should make up at least 2% of the total area of the pupil. The Allowing an uncorrected center results in a lens in the Usually at a great price advantage across from the lenses corrected throughout the pupil. This applies before everything for test objectives with a comparatively large one Working distance.

If the only main plane or one of the two main planes of the refractive power-variable, imaging component lies in the focal plane of the test objective or in a plane that is optically conjugated to this focal plane, this component in a chromatic-confocal arrangement generally does not result in any additional chromatic transverse error. Since the test objective and the first tube objective can also be designed with low chromatic transverse aberrations, there is the advantage of a low overall chromatic transverse aberration in the chromatic-confocal arrangement. It is generally advantageous if, for the center of the depth range Δz in the object space, at least approximately plane wave fronts in the common plane of the corresponding main plane of the refractive power variables, imaging component, pupil plane and focal plane of the test objective. Then the center of the depth range coincides at least approximately with the focal plane of the test lens in the object space. A test lens can be selected and used from the large number of lenses corrected for infinity in the area of the best correction.

It can be used to the advantage of a one-stage structure for the refractive power variable, imaging component, if the tube lens is at least approximately achromatic is. If the microlens array illuminated by a light source when viewed through the tube lens in an intrafocal position is created after the tube lens for the light of all wavelengths virtual image. Only in cooperation with that of the tube lens subordinate, refractive power variable chromatic, imaging component, the latter then having a positive refractive power, that is Microlens array then for a wavelength, Approximately in the middle of the spectral range, imaged to infinity. This is how a test lens corrected to infinity is at its best Correction used. Moreover the main level of the refractive power, chromatic, imaging component with the focal plane of the test lens, which is based on the side of the test lens facing away from the object or in a this focal plane is optically conjugate plane, at least approximately coincide. The refractive power variable, chromatic, imaging Component can then be made from a Fresnel lens or a diffractive one Microstructure exist, which has the known imaging effect a lens or a lens. With the Fresnel lens or even with the microstructure, you can use an annular diaphragm the center area will be hidden. So the problem with light out of unwanted Diffraction orders, for example by means of further subordinate, annular diaphragms, be reduced. This is especially for the optical scanning of comparatively small object fields very well applicable.

there can the diffractive microstructure of the subcomponent in the refractive power variable, imaging component also electronically by means of a lattice structure controlling subcomponent, for example an LCD, an LCOS display (Liquid crystal on silicon display) or a DMD (Digital micro mirror device), designed for the electronic generation of a required mapping function to be able to electronically generate a required mapping function to make the lateral formation of the same specifically adjustable. Doing so during the electronically adjusted microstructure during a measuring process but not changed, is for this time range fixed. The confocal sensor is working chromatic-confocal with static subcomponents. The electronic Adjusting the lattice structure is only for optimal adjustment of the confocal sensor to a given measurement task. For example can if a big one Depth measuring range required the lattice constant of the electronically controllable lattice on average can be made comparatively small, so that the chromatic splitting is large in this case. The foregoing features are set out in claims 1 to 5 recorded.

The the following feature is covered by claim 6. Secondly but it is also possible according to the invention that refractive power variable, imaging component not as a chromatic, but rather as an electronically controllable system or to build up as a sub-component in this system in order to focus through to allow electronically controlled. This refractive power variable, imaging component on the basis of, at least the lateral microstructure electronically controlling component or Subcomponent can be built comparatively compact. It can an LCD, an LCOS display or a DMD for electronic generation one needed Mapping function can be used. So the refractive power in particular dependent on from the lateral microstructure of an electronically controllable array can be varied in a predetermined manner so that at least the spatial frequencies the lateral microstructure of the same can be changed in a targeted manner can. It is also possible, with a single LCOS display, a refractive power variable, imaging Build component. This LCOS display is in a known manner assigned a beam splitter. The feature below is indicated by captured the claim 6.

at Use of a DMD as a refractive power variable, imaging component this is preferably a lens with a decentered, circular pupil surface and this in turn preferably a microlens array with decentered ones Microlenses upstream to the light energy of the upstream light source optimal use.

The following feature is covered by method claim 7: In the case of a confocal arrangement with a refractive power-variable, imaging component with a test objective and with a tube objective, with a light source, this component can also be designed as an electronically controllable component, so that the refractive power thereof depends on an electronic control can be changed and, according to the invention, the main plane of this component is arranged at least approximately in the focal plane of the test lens facing away from the object or in a plane optically conjugate to this focal plane, this plane simultaneously at least approximately also the pupil plane of the overall system for the Representing object lighting and object illustration.

The the following features are covered by claims 8 to 11. A confocal arrangement with refractive power variable, imaging component consists of a test lens, usually from a tube lens and from a light source, whereby the refractive power variable imaging component also at least one has diffractive component. This is considered an electronically controllable, diffractive Component formed, which as an amplitude or as a phase grating is formed and the effect of a single lens, a lens or a mirror, so preferably only a single one has optical axis. So the refractive power can be dependent in particular very much of the lateral microstructure of an electronically controllable array changed quickly become. The main level is the electronically controllable, diffractive Component at least approximately in the focal plane of the test lens facing away from the object or in a closed this focal plane arranged optically conjugate, this Level at least approximately at the same time also the pupil level of the overall system for object lighting and Represents object illustration. Exactly these described features now lead to that then when there is a change the refractive power of the refractive power variable, imaging component itself the desired depth shift the images of the light source points in the object space for optical scanning of the object results, whereby, and this is the particularly advantageous, the Heavy beam remains at least approximately unchanged in its position. Since this plane represents both the pupil and the focal plane, the heavy beams at least almost always telecentric. This represents an optimal technical functionality for the three-dimensional optical scanning of an object in depth.

Farther is more confusing in the confocal arrangement with refractive power variable Component of the electronically controllable, diffractive sub-component preferably at least one passive, diffractive subcomponent with at least approximately the same refractive power and the opposite effect assigned. In this case, an infinity corrected can also be used Tube lens can be used.

In a confocal arrangement with refractive power variable, imaging Component for determining the distance or the two or the three-dimensional profile of the surface of an object can electronically controllable diffractive subcomponent in action designed as a comparatively strongly decentered imaging system his. To achieve this, the microstructures are on the diffractive Subcomponent preferably only comparatively slightly curved, see above that the main point of the effective imaging system is preferred outside the effective area this subcomponent. The illuminating beam of light falls preferably at an angle of incidence of a few degrees diffractive sub-component and leaves this sub-component through Diffraction of light with a main beam approximately perpendicular to the active surface in the direction Prüfobjektiv, being the bundle by means of electronically controllable, diffractive subcomponents, ie electronically is focused or diverged to control the images of the light source points shift in depth in the object space for confocal scanning to be able to. For coupling the light beam this electronically controllable diffractive subcomponent is preferred another diffractive, but static working sub-component is assigned, the microstructure being diffractive, static working sub-component in the field preferably a constant spatial frequency which, at least approximately that of the middle electronically controllable, diffractive subcomponent equivalent. This is the electronically controllable, diffractive sub-component preferably at least approximately arranged in parallel. The static working subcomponent can but preferably also be designed to be electronically controllable. At about the same lattice constants of the two subcomponents result for the Main rays on the way from static to controlled subcomponent one Zigzag structure with parallel input and output bundle main beams. So it turns out a compensating effect for the beams inclined to the main beam in a bundle. The diffractive, statically operating subcomponent can preferably be used also be designed as a blazed grid, the microstructure of which has a constant spatial frequency in the field. This leads to a single wavelength of light and an adapted microstructure for high diffraction efficiency.

Farther shows in the confocal arrangement with refractive power variable, imaging Component preferably the refractive power variable, imaging component an annular Effective area on, so that the middle area is shaded.

The following feature is covered by method claim 12. In the confocal method with a refractive power-variable, imaging component, a test objective and generally also also with a tube objective and a light source, wherein the refractive power-variable, imaging component can also have at least one diffractive component, the tube objective and the electronically controllable, diffractive components matched to one another so that light from each source point in front of the tube lens is the electronically controllable, diffractive component in the form of plane waves in the direction of the test object tiv leaves. This should be done at least approximately for a medium spatial frequency that is optically easily adjustable by the electronically controllable diffractive component. Thus, the refractive power of the electronically controllable, diffractive component in cooperation with the tube lens produces an image of the light source points to infinity. With regard to the tube lens, for example, there is an intrafocal position of the light source points. The refractive power of the double system, consisting of a tube lens and an electronically controllable, diffractive component, is increased by the electronically controllable, diffractive component so that the light source points are now in the effective focal plane of this double system, i.e. by the double system towards infinity be mapped. An extrafocal position of the light source points can also be used by utilizing the light-scattering effect of an electronically controllable, diffractive component. As already shown, the pupil function of the overall system for object illumination and imaging is realized simultaneously and at least approximately in the focal plane of the test objective facing away from the object. This method thus enables images of the light source point to be shifted along heavy beams which are at least approximately telecentric over a comparatively large depth range because of the at least approximate pupil position in the focal plane of the test objective facing away from the object. This is very advantageous for a large number of measurement applications in confocal technology.

The the following features are assigned to claims 13 to 19. So it gets confocal with a light source and a test lens performed at least the following: That of each light source point in a confocal arrangement, for example for the detection of the two- or three-dimensional micro profile of an object, outgoing wavefront can, but does not have to, can be changed in their radius of curvature by a first lens. This first lens can be a tube lens. In the focal plane the test lens, which faces away from the object or in a focal plane optically conjugate plane, this plane also the pupil plane of the imaging beam path, is experienced by a refractive power variable imaging component, this one Part of a complex optical system or even a single one Element, any incident wavefront, can be largely independently of their direction of propagation, a change in the radius of the wavefront. The radius of the wavefront resulting from this component should be preferably be comparatively large. This change in Radius' of the wavefront by means of a refractive power-variable, imaging component in the object space the laws of optics always in the optical axis of the test lens parallel shift of the associated image of a light source point changed. According to the method, this z-shift results in a optical scanning of the object in depth with images of light source points in a telecentric beam path. The backscattered object or even reflected light passes through this optical confocal Arrangement over that bündelbegrenzende System, here preferably a fixed microlens array a detector, usually an areal camera. For confocal Point detectors can also be used in line cameras. It arises dependent on the known confocal of the component's refractive power variation Signal. Is this dependency chromatic, can be spatially resolved, So in every detected object point, by means of spectrometric Analysis of the known confocal signal obtained as a function of the light wavelength be by the intensity distribution dependent on on the wavelength of light is detected, which then corresponds to the known confocal signal. The confocal signal therefore exists completely at any time. this makes possible also the two- or three-dimensional scanning of fast moving objects, if a short-pulse light source, the light pulses for example with a half-width in the microsecond range, or with a camera a short shutter time is used.

The spectrometric analysis with a line-shaped scanning of the object preferably with a confocal arrangement with at least one Row of microlenses can be used with a light-decomposing, chromatic Prism wedge or a diffraction grating or a combination the same in the infinity beam path of an afocal imaging level, that precedes a monochrome camera. This light-separating component can also be designed as a straight-ahead component and is best located in or near the common inner focal plane of this afocal imaging level. This component is dimensioned in its light-decomposing effect so that a to the size of the area of the monochrome Lateral splitting of the light generated by camera chips becomes. So the light from the object surface can be distributed in a suitable light laterally split on the camera chip, and it can be done with a a sufficiently large depth measuring range along at least a single line on the object.

However, multi-chip cameras, preferably a four-chip camera, can also be used for spectrometric analysis. This is a possibility if the object is to be scanned in depth and over a large area, that is to say three-dimensionally. The spectral region to be evaluated can preferably be divided into eight spectral channels by beam splitting by means of edge-splitting "color splitters. In this case, each of the four camera chips is preferably preceded by a Köstersprisma with a spectrally adapted color splitter with an edge characteristic. There are two at each output of a Köstersprism parallel optical light beams that transmit one image each and so each camera chip detects two adjacent images in a different spectral range. However, cameras with more than four camera chips can also be used. Newly developed volume camera cameras are particularly advantageous for this application. Chips that work spectrally sensitive in depth, so a very compact arrangement can be built up.

Consists this dependency the refractive power, however, through diffraction, i.e. through the formation of diffractive Structures of an electronically controlled amplitude or phase grating, the known confocal signal arises depending on the set one average lattice constant or the average spatial frequency of the phase grating, which about controlled in time is, so that the known confocal signal ultimately also over the Time arises. This approach, however, is more quiescent or more for scanning suitable for objects that move less quickly.

The refractive power variable, imaging component can also be different Times represent a differently decentred lens. In the chromatic case, preference is given to lateral movement the optical axis of this lens by means of a swinging movement optical axis of the test lens each deflected a little. So feel the images of the light source points Object in a much finer lateral scale than through the distances the images of the light source points is specified. So the lateral resolution the confocal arrangement can be significantly increased.

in the Case of an electronically controlled amplitude or phase grating As a refractive power imaging component can be controlled by an electronic control the effective optical axis of this component laterally positioned that the images of the light source points here too scan the object on an even finer lateral scale than through the distances the images of the light source points on the object is predetermined. So can be the center of curvature the one in the test lens incoming wave fronts are predetermined laterally displaced, by thus the effective optical axis of the refractive power variable, imaging component is laterally and predetermined shifted and thus the lateral position of the images of the light source points is also predetermined is changed by an electronic control on the object.

So can be done with a confocal arrangement without moving components, so solely by means of a refractive power-variable, imaging component, which then as an electronically controlled amplitude or phase grating is formed, the object space by controlling the location of the Images of the light source points are scanned in two or three dimensions and with high spatial resolution become. So even with a confocal procedure, the electronically controllable effective optical axis of the refractive power, imaging Component laterally positioned to the object in a still scanning the finer lateral scale.

The chromatic, refractive power variable, imaging component can be precise on the existing chromatic longitudinal aberrations of the components of the confocal arrangement. So can an adjusted, total longitudinal chromatic aberration of the confocal Arrangement are generated for a desired one Scale of two- or three-dimensional scanning optimally suitable is.

Basically is but it is also possible for example for the measurement of macroscopic objects in the order of magnitude of 200 mm × 200 mm × 200 mm, that a refractive power variable arrangement as a 2f1-2f2 arrangement, or as a 4f arrangement, with two lenses and that the Refractive power variable, imaging component with at least one diffractive Lens or reflector at least approximately in the common inner focal plane is arranged. The refractive power variable, imaging Component can also be controlled electronically for focusing be constructed. The last focal plane of the 2f1-2f2 arrangement, or the 4f arrangement, at least approximately in the direction of illumination with the focal plane of the test object lens together, which faces away from the object. The pupil is inside Focal plane of the 2f1-2f2 arrangement, or the 4f arrangement, or in arranged to this optically conjugate plane. Is possible but also an arrangement of the pupil diaphragm in the one facing the object Focal plane of the test object lens. The test object lens in cooperation with the 2f1-2f2 arrangement and the refractive power variable, imaging component be at least approximately diffraction limited, with it for the macroscopic confocal arrangement gives a high depth resolution can.

The following is covered by claim 2: A confocal arrangement, which is designed in particular for macroscopic objects, has a refractive power, imaging component with a test lens, wherein the refractive power, variable imaging component can also have at least one diffractive subcomponent. According to the invention, a main level is the Refractive power variable, imaging component at least approximately in the focal plane of the test lens facing away from the object or in a plane optically conjugate to this focal plane. The focal plane of the test objective facing the object at least approximately represents the pupil plane of the overall system for object illumination and imaging. However, the pupil plane can also be arranged in a plane that is optically conjugate to this focal plane. A macroscopic object can also be scanned with a confocal arrangement. With this arrangement there is telecentricity in the array space and there is a central perspective beam path in the object space.

Description of the figures

The invention is illustrated by way of example 1 to 10 described. In 1 becomes the effect of a refractive power variable, imaging component 7 shown. In case A is the refractive power of this chromatic, refractive power variable, imaging component 7 zero, i.e. without any optical effect except for the shift due to its optical thickness. The main plane H'7 of this chromatic, refractive power-variable, imaging component 7 coincides with the focal plane of the test lens 12 together. In case B, the effect of the maximum wavelength should be shown in the evaluated spectrum. In this case the refractive power of this chromatic, refractive power variable, imaging component 7 so that the light is maximally diverging. The radius of the incident wavefront is changed and diverged. This leads to a z-displacement of the image of the light source point LBQ, that is to say to a greater distance from the test objective 12 , The image of the light source point LBQ is z-shifted due to the effect of the shade 8th parallel to the axis of the test lens 12 , There is a telecentric beam path in the object space, which also exists for wave fronts in front of the test lens 12 have an inclination to the optical axis. In case C, the effect of the minimum wavelength should be shown in the evaluated spectrum. Then the refractive power of this chromatic, refractive power variable, imaging component 7 maximum light-collecting. The incident wave front is thus changed in its radius and converges. This leads to a z-displacement of the image of the light source point LBQ, so that the distance from the test objective 12 reduced. In this way, a range Δz can be scanned in depth. This scan is performed simultaneously on a plurality of light source points belonging to an array.

In 2 a complete confocal arrangement is shown. The refractive power, imaging component 7 is chromatic. The light from a polychromatic light source 1 using a collimator 2 collimated, passes a beam splitter 3 and illuminates the line-shaped microlens array 4 , here in the 2 a rotation of the microlens line for better illustration 4 by 90 °. The wavefront from a light source point LQ from a focus of a microlens 5 of the microlens array 4 goes out, is using a tube lens 6 mapped to infinity meets a chromatic, refractive power variable, imaging component 7 in the the object 13 facing focal plane of the test lens 12 , The Leica Planapochromat 1.6 × objective from the Leica MZ12 stereomicroscope serves as the test objective and as the tube objective 6 the Leica Planapochromat objective 1 × of the same stereomicroscope system. The refractive power, imaging component 7 is only considered as an overall system here. This is a circular shading 8th assigned. In case A according to 1 is the refractive power of this component 7 at a certain wavelength approximately in the middle of the spectral range used zero. An incident wavefront is not changed in its radius in this way, so it remains flat and is checked by the test lens 12 on the object 13 focused where the image of the light source point LBQ in focus F 'of the test lens 12 arises. That of the object 13 backscattered light is again from the test lens 12 captured and can according to the tube lens 6 the associated microlens 5 happen. On the beam splitter 3 the light beam is decoupled and is through the afocal imaging level, consisting of the lenses 14 and 17 and the confocal aperture 15 and a light-breaking, chromatic straight wedge 16 , on a CMOS camera 18 displayed. Through the bezel 15 in the common inner focal plane of the lenses 14 and 17 can only light the CMOS camera 18 achieve which is at least approximately the focus range of the microlens 5 happened. The backscattered light from the focus area of the microlens 5 to form the confocal signal. The straight wedge 16 , which is best located in or near the common inner focal plane of the afocal imaging level, is dimensioned in its light-dissociating effect in such a way that the CMOS camera too 18 adapted, spectral splitting is generated, which for example the light of the light source to 256 pixels on the CMOS camera 18 disassembled so that a sufficiently large depth measuring range Δz can be recorded along a line with the confocal arrangement. With a CMOS camera 18 With 1024 pixels, the optical signals of four rows of microlenses lying next to each other at a corresponding distance can be captured.

The 3 shows a lens system as a sub-component 7.1 with an external main plane H'7.1 and with a microstructure applied to a flat carrier 7.4 which lies in the main level H'7.1. The circular shading 8th is into the microstructure 7.4 integrated.

The 4 represents an arrangement with an at least partially achromatic diffractive subcomponent 7.2 , which is described in the book "Mikrooptik" by St. Sinzinger, J. Jahns, Wiley-VCH-Verlag, 1999, page 367 as Multi order lens, and with a chromatically diffractive subcomponent 7.5 as a chromatic, refractive power variable, imaging component 7 The at least partially achromatic subcomponent 7.2 can also be designed as a Fresnel lens.

5 represents an array with a lens group 7.3 as a subcomponent and an electronically controllable, diffractive amplitude grating 7.6 as a sub-component for a chromatic, refractive power, imaging component 7 represents.

6 represents an arrangement with a passive, diffractive phase grating 7.2 as a sub-component and with an electronically controllable diffractive phase grating 7.7 which with the passive, diffractive phase grating 7.2 to a chromatic, refractive power, imaging component 7 connected is. This also gives the possibility of the controllable, diffractive phase grating 7.6 to be controlled so that a controlled decentering of the chromatic, refractive power variable, imaging component 7 in the direction perpendicular to the plane of the drawing. The images BLQ of the light source points LQ can also be controlled laterally on a fine scale, so that, if necessary, a high lateral resolution of the object 13 in the direction perpendicular to the plane of the drawing.

The 7 shows part of a confocal arrangement. There is therefore no telecentric beam path for imaging the light source points LQ. However, this is for a comparatively large focal length of the chromatic, refractive power variable, imaging component 7 and tolerable for a comparatively small field and for adapted lighting.

The 8th provides a lens group as a subcomponent 7.1 with a reflective, diffractive, electronically controllable phase grating 7.8 and a beam splitter 18 is coupled. The main plane H'7.1 of the lens group 7.1 coincides with the grating plane of the phase grating 7.8 together. The circular ring aperture 8th is only shown symbolically as this is in the phase grating 7.8 is integrated.

The 9 represents an arrangement with a single, reflective, diffractive, electronically controllable phase grating 7.8 with a beam splitter 18 This arrangement is very simple. Here too is the circular shading 8th only shown symbolically, as this is already in the phase grating 7.8 is integrated.

The 10 makes an order accordingly 2 , but here with a static, reflection grating 7.9 , which is formed with equidistant structures, i.e. is monofrequent. This grid 7.9 can be designed as a blazed grid. The incident light beam is diffracted in the direction of an electronically controllable reflective grating 7.10 that the grid 7.9 is subordinate. The electronically controllable reflective grating 7.10 is designed here as an LCOS display or as a DMD, so that a very high dynamic range can be achieved. This electronically controllable reflective grating 7.10 emulates a highly decentered mirror. The refractive power of the grating is controlled by electronic control 7.10 changed in amount and sign. When the value of the focal length infinite is "passed through", the location of the main point of the imaging system is jumped laterally 7.10 light-collecting as well as light-scattering for the purpose of focusing.

Claims (21)

Confocal arrangement with refractive power, imaging component with a test lens ( 12 ), with the refractive power variable imaging component ( 7 ) also at least one diffractive subcomponent ( 7.2 and 7.4 to 7.8 ), characterized in that a main plane of the refractive power variable imaging component ( 7 ) at least approximately in the object ( 13 ) facing focal plane of the test lens ( 12 ) or is arranged in a plane that is optically conjugated to this focal plane, this plane at least approximately also representing the pupil plane of the overall system for object illumination and imaging. Confocal arrangement, especially for macroscopic objects with a refractive power-variable, imaging component with a test objective ( 12 ), with the refractive power variable imaging component ( 7 ) also at least one diffractive subcomponent ( 7.2 and 7.4 to 7.8 ), characterized in that a main plane of the refractive power variable imaging component ( 7 ) at least approximately in the object ( 13 ) facing focal plane of the test lens ( 12 ) or in a plane that is optically conjugated to this focal plane, the object ( 13 ) facing focal plane of the test lens ( 12 ) or in a plane optically conjugated to this focal plane at least approximately represents the pupil plane of the overall system for object illumination and imaging. Confocal arrangement with refractive power-variable, imaging component ( 7 ) according to claim 1, characterized in that at least the test objective ( 12 ) a middle shade ( 9 ), which makes up at least 2% of the total pupil area of the same. Confocal arrangement with refractive power-variable, imaging component ( 7 ) according to at least one of claims 1 to 3, characterized in that a diffractive-chromatic ( 7.4 to 7.7 ) and an at least approximately achromatic subcomponent ( 7.1 to 7.3 ) to a variable, chromatic component ( 7 ) are connected. Confocal arrangement with refractive power-variable, imaging component ( 7 ) according to at least one of claim 4, characterized in that an at least approximately achromatic subcomponent ( 7.2 ) is diffractive and the microstructures of the at least approximately achromatic subcomponent ( 7.2 ) the microstructures of a diffractive-chromatic lens ( 7.5 ) are arranged directly opposite each other. Confocal arrangement with refractive power-variable, imaging component ( 7 ) according to at least one of claims 1 to 5, characterized in that the sub-component in the refractive power-variable, imaging component is also formed by means of a sub-component that electronically controls the lattice structure, for example an LCD, an LCOS display or a DMD, in order to generate the electronic components to make a required imaging function selectively adjustable with regard to the lateral configuration thereof, the electronically set microstructure not being changed during a measuring process, however, and the confocal sensor operating in a chromatic-confocal manner. Confocal arrangement with refractive power-variable, imaging component ( 7 ) according to at least one of claims 1 to 6, characterized in that an electronically controllable array, at least one LCD ( 7.5 . 7.6 ), at least one LCOS diplay ( 7.8 . 7.10 ) or at least a single DMD is used to generate the imaging function, the spatial frequency of the lateral microstructure thereof being varied in a predetermined manner. Confocal arrangement with refractive power, imaging component with a test lens ( 12 ) and with a tube lens ( 6 ), with a light source ( 1 ), characterized in that, the component is designed as an electronically controllable component, so that the refractive power thereof is changed as a function of an electronic control and the main plane of the component is at least approximately in that of the object ( 13 ) facing focal plane of the test lens ( 12 ) or is arranged in a plane that is optically conjugated to this focal plane, this plane at the same time at least approximately also representing the pupil plane of the overall system for object illumination and object imaging. Confocal arrangement with refractive power, imaging component with a test lens ( 12 ) and with a tube lens ( 6 ), with a light source ( 1 ), with the refractive power variable imaging component ( 7 ) also at least one diffractive subcomponent ( 7.6 . 7.7 . 7.9 ), characterized in that, the diffractive sub-component as an electronically controllable diffractive sub-component ( 7.6 to 7.8 . 7.10 ) which is designed as amplitudes ( 7.6 . 7.10 ) or as a phase grating ( 7.7 . 7.8 and 7.10 ) is designed and simulates the effect of a single lens, a lens or a mirror, so that the refractive power is changed depending on the lateral structure of an electronically controllable array and the main plane of the electronically controllable, diffractive subcomponent ( 7.6 to 7.8 ) at least approximately in the object ( 13 ) facing focal plane of the test lens ( 12 ) is arranged, this level at the same time at least approximately also representing the pupil level of the overall system for object illumination and object imaging. Confocal arrangement with refractive power-variable, imaging component ( 7 ) according to claim 9, characterized in that, the electronically controllable diffractive sub-component ( 7.6 and 7.7 ) at least one passive diffractive subcomponent ( 7.2 or 7.3 ) with at least approximately the same refractive power and the opposite effect. Confocal arrangement with refractive power, imaging component according to claim 10, characterized in that, the electronically controllable diffractive sub-component ( 7.10 ) designed as a comparatively strongly decentered imaging system, so that the main point of the imaging system is clearly outside the effective area of the imaging system and the same has a further diffractive, statically working sub-component ( 7.9 ) this electronically controllable, diffractive subcomponent ( 7.10 ) is assigned, the microstructure of the diffractive, statically operating subcomponent ( 7.9 ) has a constant spatial frequency in the field, which corresponds at least approximately to that of the electronically controllable, diffractive subcomponent, and this to the electronically controllable, diffractive subcomponent ( 7.10 ) is arranged at least approximately in parallel. Confocal arrangement with refractive power-variable, imaging component ( 7 ) according to claim 11, ge is characterized by the fact that the diffractive, statically working sub-component ( 7.9 ) is designed as a blazed grid, the microstructure of which has a constant spatial frequency in the field. Confocal procedure with refractive power, imaging component ( 7 ) with a test lens ( 12 ) and with a tube lens ( 6 ), with a light source ( 1 ), with the refractive power variable imaging component ( 7 ) can also have at least one diffractive component, characterized in that the refractive power-variable, imaging sub-component ( 7.6 to 7.8 ) is electronically controllable and that the tube lens ( 6 ) and the electronically controllable, diffractive subcomponent ( 7.6 to 7.8 ) are coordinated with one another in such a way that at least approximately for a medium, optically easily adjustable spatial frequency in the electronically controllable, diffractive component ( 7 ) Light from each source point in front of the tube lens ( 6 ) the electronically controllable, diffractive component at least approximately in the form of plane waves in the direction of the test objective ( 12 ) leaves. Confocal method, especially for the measurement of macroscopic objects, with a refractive power-variable, imaging component ( 7 ) with a test lens ( 12 ) and with a tube lens ( 6 ), with a light source ( 1 ), with the refractive power variable imaging component ( 7 ) can also have at least one diffractive component, characterized in that a refractive power-variable arrangement is constructed as a 2f1-2f2 arrangement, or as a 4f arrangement, with two objectives and the refractive power-variable, imaging component ( 7 ) with at least one diffractive lens is arranged at least approximately in the common inner focal plane and the last focal plane of the 2f1-2f2 arrangement, or the 4f arrangement, in the illumination direction coincides at least approximately with the focal plane of the test object lens, which faces away from the object and the pupil is arranged in the inner focal plane of the 2f1-2f2 arrangement, or the 4f arrangement, or in a plane that is optically conjugate to it. Confocal method for optical scanning with a test lens ( 12 ) and with a light source ( 1 ), characterized in that the wavefront emanating from each light source point in a confocal arrangement in the focal plane of the test objective ( 12 ) that the object ( 13 ) facing away or in a plane optically conjugate to this focal plane, this focal plane also representing the pupil plane of the imaging beam path, by a refractive power-variable imaging component ( 7 ) and at least approximately independently of their direction of propagation, experiences a change in the radius of the wavefront, and this change in the radius of the wavefront in the object space always in a direction relative to the optical axis of the test objective ( 12 ) parallel shift of the associated image of a light source point is converted and thus an optical scanning of the object ( 13 ) in depth with images of light source points in an at least approximately telecentric beam path and that of the object ( 13 ) backscattered or reflected light due to the confocal arrangement on a detector, usually an areal camera ( 18 ), and depending on the refractive power variation of the refractive power variable, imaging component ( 7 ) the known confocal signal is created. Confocal method according to at least one of claims 14 or 15, characterized in that the center of curvature of the in the test lens ( 12 ) entering the wavefronts is predetermined laterally shifted. Confocal method according to claim 16, characterized in that the center of curvature of the in the test lens ( 12 ) entering the wavefronts is laterally shifted by the effective optical axis of the refractive power variable imaging component ( 7 ) is laterally positioned by means of electronic control so that the images of the light source points are the object ( 13 ) on an even finer lateral scale. Confocal method according to at least one of Claims 14 to 17, characterized in that the refractive power-variable imaging component ( 7 ) is chromatic and the known confocal signal is obtained as a function of the light wavelength by means of spectrometric analysis. Confocal method according to at least one of claims 14 to 18, characterized in that a multi-chip camera is used as the detector and the spectral range to be evaluated by beam splitting divided into several spectral channels is, each of the camera chips each a Köstersprisma with a spectral adjusted color dividers upstream with an edge characteristic is. Confocal method according to at least one of Claims 14 to 19, characterized in that the refractive power-variable imaging component ( 7 ) is electronically controllable diffractive and the refractive power of the refractive power variable imaging component is controlled by an electronically controlled spatial frequency variation ( 7 ) is changed. Confocal method according to at least one of claims 14 to 20, characterized in that the effectively acting optical axis of the refractive power variable imaging component (electronically controllable) 7 ) positioned laterally that the images of the light source points represent the object ( 13 ) on an even finer lateral scale.