CA2054928A1 - Optical device with confocal beam path - Google Patents
Optical device with confocal beam pathInfo
- Publication number
- CA2054928A1 CA2054928A1 CA002054928A CA2054928A CA2054928A1 CA 2054928 A1 CA2054928 A1 CA 2054928A1 CA 002054928 A CA002054928 A CA 002054928A CA 2054928 A CA2054928 A CA 2054928A CA 2054928 A1 CA2054928 A1 CA 2054928A1
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- illumination
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- detector
- illumination grid
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- 230000003287 optical effect Effects 0.000 title claims abstract description 17
- 238000005286 illumination Methods 0.000 claims abstract description 80
- 238000011156 evaluation Methods 0.000 claims abstract description 9
- 230000005540 biological transmission Effects 0.000 claims description 8
- 230000005855 radiation Effects 0.000 abstract description 3
- 239000004973 liquid crystal related substance Substances 0.000 description 7
- 238000006073 displacement reaction Methods 0.000 description 6
- 230000000694 effects Effects 0.000 description 5
- 238000003384 imaging method Methods 0.000 description 5
- 239000011521 glass Substances 0.000 description 4
- 230000002226 simultaneous effect Effects 0.000 description 3
- 239000011159 matrix material Substances 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 210000001747 pupil Anatomy 0.000 description 2
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- 241001237728 Precis Species 0.000 description 1
- 101100313003 Rattus norvegicus Tanc1 gene Proteins 0.000 description 1
- 238000003491 array Methods 0.000 description 1
- 238000009924 canning Methods 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 239000011651 chromium Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 229910052736 halogen Inorganic materials 0.000 description 1
- 150000002367 halogens Chemical class 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000000737 periodic effect Effects 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B21/00—Microscopes
- G02B21/0004—Microscopes specially adapted for specific applications
- G02B21/002—Scanning microscopes
- G02B21/0024—Confocal scanning microscopes (CSOMs) or confocal "macroscopes"; Accessories which are not restricted to use with CSOMs, e.g. sample holders
- G02B21/008—Details of detection or image processing, including general computer control
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B9/00—Measuring instruments characterised by the use of optical techniques
- G01B9/04—Measuring microscopes
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B21/00—Microscopes
- G02B21/0004—Microscopes specially adapted for specific applications
- G02B21/002—Scanning microscopes
- G02B21/0024—Confocal scanning microscopes (CSOMs) or confocal "macroscopes"; Accessories which are not restricted to use with CSOMs, e.g. sample holders
- G02B21/0036—Scanning details, e.g. scanning stages
- G02B21/004—Scanning details, e.g. scanning stages fixed arrays, e.g. switchable aperture arrays
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B21/00—Microscopes
- G02B21/0004—Microscopes specially adapted for specific applications
- G02B21/002—Scanning microscopes
- G02B21/0024—Confocal scanning microscopes (CSOMs) or confocal "macroscopes"; Accessories which are not restricted to use with CSOMs, e.g. sample holders
- G02B21/008—Details of detection or image processing, including general computer control
- G02B21/0084—Details of detection or image processing, including general computer control time-scale detection, e.g. strobed, ultra-fast, heterodyne detection
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Optics & Photonics (AREA)
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Computer Vision & Pattern Recognition (AREA)
- Microscoopes, Condenser (AREA)
- Length Measuring Devices By Optical Means (AREA)
- Investigating Or Analysing Materials By Optical Means (AREA)
- Investigating, Analyzing Materials By Fluorescence Or Luminescence (AREA)
- Measurement Of Optical Distance (AREA)
Abstract
Abstract:
Optical Device With Confocal Beam Path For Three-Dimensional Examination of an Object (Figure 1) A device is described for three-dimensional examination with a confocal beam path, in which an illumination grid (12; 22; 31;
83) is imaged in a focal plane (13f; 87), said plane being located on or in the vicinity of surface (14o) of object (14).
The radiation reflected in the focal plane is imaged directly by a beam splitter onto the receiving surface of a CCD receiver (17;
91). The illumination grid (12; 22; 31; 83) is then imaged on the receiver surface either by the photosensitive areas of the receiver acting as confocal diaphragms or by signals from the detector elements which only receive light directed outside focal plane (13f; 87) not being taken into account in the evaluation or being taken into account separately.
The illumination grid size generated in focal plane (13f; 87) can be either fixed or variable. A variable illumination grid size can be produced for example by an LED array. The device also makes examinations in transmitted light possible.
Optical Device With Confocal Beam Path For Three-Dimensional Examination of an Object (Figure 1) A device is described for three-dimensional examination with a confocal beam path, in which an illumination grid (12; 22; 31;
83) is imaged in a focal plane (13f; 87), said plane being located on or in the vicinity of surface (14o) of object (14).
The radiation reflected in the focal plane is imaged directly by a beam splitter onto the receiving surface of a CCD receiver (17;
91). The illumination grid (12; 22; 31; 83) is then imaged on the receiver surface either by the photosensitive areas of the receiver acting as confocal diaphragms or by signals from the detector elements which only receive light directed outside focal plane (13f; 87) not being taken into account in the evaluation or being taken into account separately.
The illumination grid size generated in focal plane (13f; 87) can be either fixed or variable. A variable illumination grid size can be produced for example by an LED array. The device also makes examinations in transmitted light possible.
Description
2~4928 Specification: 900~2 P
ODtical Device With Confocal Beam Path For Three-Dimensional Examination of an Obiect The present invention relates to a devics for three-di~ensional examination of an object according to the preamble of Claim 1.
A device in the form of a confocal scanning microscope is described in a publication by D. ~. Hamilton, et al. (Appl. Phy~.
B 27, 211 (1982)). Scanning micro~copes with confocal beam paths, in which a so-called point light source is imaged on a plane of the object and this plane of the object is imaged on a so-called ~pot receiver or hole diaphragm behind which a receiver is located, have the property of being very height-~elective, in other words of optically separating planes that are only a short distance apart. In the above publication, this property i9 u~ed to record a curface profile of a ~emiconductor component. For this purpose, for each x-y po~ition of the light spot, the object i~ moved in the z direction (direction of the optical axis) and the intensity curve i9 mea-cured. Since the latter has a pronounced maximum when the image of the light ~pot is located precisely on the surface, the height of the surface in the z direction can be determined for every point in the x-y plane and the entire surface profile of the object can be recorded ~equentially in this manner as a function of time.
. .
20~2~
One disadvantage of this known device is that the recording of a surface profile requires a relatively long time since only one individual object point is scanned at each point in time.
Moreover, a confocal microscope is known from U.S. Patent 4,407,008 in which a one~`or two-dimensional luminou~ diode array is imaged in the object plane. The light scattered or reflected at the object ~urface is then imaged on a one-dimensional or two-dimensional detector diode array. Thi~ microscope permits scanning an object without deflecting the light beam mechanically or moving the object, but here again only a single small area of the object is illuminated at each point in time so that once again a relatively long time is required to record a surface profile.
The goal of the pre3ent invention is to provide a device by which three-dimensional optical examinations can be conducted in a relatively short time.
The stated goal is achieved according to the invention by a device w1th the features of Claim 1.
In the device according to the invention, the il-lumination grid simultaneou~ly produces a plurality of separate light ~pot~ ~n the focal plane so that a correspondingly large number of object point~ can be measured simultaneou~ly. The d1~tanc~ between the 2 ~
light spots, in other word~ the illumination grid si~e, roughly corre~ponds to t~o to ten times their diameter. This illumination grid scale is either imaged on the detector grid in such a way that the image of the illumination grid size i~
greater than the detector grid ~ie or the detector grid is larger than the diameter or edge lengths of the photo~ensitive surfaceq of the individual detector elements. In both alternative embodimentq, the detector grid simultaneou~ly serves as the detector and confocal grid. In the first case, the detector elements which in the ca~e of a plane object are located in the focal plane between ~sic] the image of the illumination grid, as a diaphragm, while the output signals from these detectors are not taken into account in the second evaluation.
In the second case the photosensitive areas between the detector elements act as confocal diaphragms.
It has been found that commercial CCD receivers are best suited a~ detector grids. The generally disadvantageous property of the~e ~ensors can then be put to use, namely that only a small part of the receiver surface con~ists of photosensitive areas.
The distance between the individual detector elements is then about five to 9iX times their diameter.
The use of a CCD receiver and a two-dimensional array of holes in an illuminated layer is known to be used in a scanning micro~cope according to U.S. Patent 4,806,00~. However, that patent merely 2 ~
states that the object can be observed in different layer planes.
In particular, the diaphragm effect of the CCD receiver is not utili~ed, namely the fact that it consi-Yts of photosensitive area~ arranged in a grid, whose dimensions are much smaller than their distances apart.
In the above-captioned U.S. Patent, the confocal beam path is used only in an incident light microscope in which the beams that travel to the object pass through the same hole array as the beams reflected from the object. It i5 therefore neaessary to use an optical element referred to as an ocular to image the hole array in a plane in which it is ob~erved or recorded. For the latter case, a video camera with a CCD receiver is mentioned, whose images can be stored and evaluated.
In the present invention on the other hand, the grid-~haped arrangement of the detector element3 of ths detector grid is u~ed.
In contrast to the above-cited publication of Hamilton and the micro cope known from U.S. Ratent 4,407,008, the solution according to the invention not only has the advantage that recording of a surface profile proceeds much more rapidly because of the simultaneous illumination of a plurality of object points, but a height-selective observation i-q al~o directly pos~ible, sinee the confocal beam ~ath means that the intensity of the 2Q~2~
radiation reflected from the individual object ~oints depends directly on the heights of the location-q in the object in question, so that each grid element provides information about the height of the surface at its point in the object and hence the inten~ity distribution over the surface provides a direct overview of the height distribution of the object surface. In particular, when the object is moved relative to the beam path in the direction of the optical axis, the areas with the same surface height can be determined very simply.
In objects with reflecting areas in or under a transparent layer, reflection profiles with a small maximum for the ~urface of the transparent layer and a large maximum for the re~lecting area are obtained to show the dependence of intensity on depth in the object. Therefore it i~ possible with the device according to the invention to in~estigate not only surface profile~ but also ~tructures within or under transparent layers.
In one advantageous simple embodiment of the invention, the illumination grid is produced by holes in a layer which is illuminated by a light source. In order to achieve a higher intensity for the illuminated holes, hereinafter referred to as light dots for short, a lens array can be disposed in front of the layer with the holes, said array servin~ to ensure that the radiation from the light ~ource does not illuminate the layer uniformly but is concentr~ted on the holes.
2 ~
Normally the CCD receiver and the illumination grid are adjusted to one another in ~uch fashion that the light dots imaged on the plane of the detector grid fall on photosensitive areas of the CCD receiver. In this case, durin~ focusing, intensity ma~ima are obtained for those object points whose reflecting ~urfaces lie exactly in the focal plane.
It i5 al~o pos~ible however to adju~t the CCD receiver and the illumination grid with respect to one another in ~uch fashion that the light dots imaged in the plane of the CCD receiver fall between the photosensitive areas of the CCD recsiver. In this case, during focusing, intensity minima are created for those object points whose reflecting ~urface3 lie precisely in the focal plane. With a special design for the CCD receiver, for example with relatively small-area non-photo~ensitive area~
between the pixels, this effect can be reinforced even further.
Finally, an inverse illumination grid i9 also possible; in other words the grid imaged in the focal plane and in the plane conjugate to the focal plane doe~ not con~i~t of bright light dots but of a bright surface with a grid-shaped arrangement of small dark zones. An illumination grid of this kind, which con~ist~ for example of a layer illuminated by the light source with nontranslucent zones, in the case of a CCD receiver ~ith small photo~en3itive areaa on which the dark ~one are imaged, 2Q~2~
likewise yields intensity minima for those object points whose reflecting surfaces lie preci~ely in the focal plane.
In another advantageous embodiment, the illumination grid is produced by a lens array which images an approximately punctate light source several times in a grid-shaped arrangement in an illumination plane.
In another advantageous embodiment~ the illumination grid is produced by the fact that a diaphragm illuminated by a light source is imaged several times in a grid-shaped arrangement in an illumination plane. In this case also, an inverse illumination grid can be produced for example by virtue of the fa~t that the diaphragm has a center which is not transluoent.
In an e~pecially advantageous embodiment, the illumination grid is produced by a light source array. This can be composed for e~ample of individual LEDs or produced by integrated technology.
In both cases it is especially advantageous to design the array~
and their voltage supply in such a way that either each individual light source or a certain number of the light sources can be turned on and off independently of the others. The si~e of the illumination grid can then be varied and~different depth resolutions can be set.
20~92~
A variable illumination grid can also be produced by making the transmission of partial areas of the illumination grid variable.
In addition, the illumination grid can be a liquid crystal matrix illuminated from behind.
To record the height-selective overview described above, it is advantageous to provide an adjusting device which makes it possible to adjust the focal plane with the images of the light dots at different layer depths in the ob~ect.
To record complete reflection profiles with good resolution it is advantageous to provide an adjusting device which makes it possible to move the illumination grid and the object relative to one another in planes perpendicular to the optical a~is so that the object is scanned with the illumination grid. The relative movement between the light dots and the object can then remain within the spacing of adjacent light dots or can be a multiple thereof. When using a variable illumination grid, rough scanning of the object can be performed on partial areas of the illumination grid that differ as a result of sequential switching.
In another advantageous embodiment of the invention the CCD
receiver is connected to a computer which evaluates the 3ignals from the CCD receiver. In this case it is advantageous to control the adjusting device~ for the relative movement of light 2 ~ 2 ~
dots and the object with respect te one another in the direction of the optical axiQ and/or in the planeQ of the li~ht dots or the object ~y using the computer.
In an especially preferred embodiment of the invention, a ~witching device is likewiQe controlled by the computer which turns different partial quantities of the light ~ources in the light source array on and off, or varies the tran~mission of different partial areas of the illumination grid. ThuY for example the number of light sources that are switched on can be controlled by the re~ults of the evaluation of the computer so that in critical areas of an object the amount of scattered light can be reduced by reducing the number of effective light ~ources.
It may be advantage~u~ when scanning an object to di~place the illumination grid really or virtually in the CCD receiver relative to one another in the illumination plane or in the plane of the diaphragm by a switching or adjusting device, which i~
advantageously controlled by the computer. By using a powerful computer, additional information can be obtained by this displacement which permits a more accurate evaluation. In this case, the grid ~ize of the illumination grid should be larger than the grid size of the photosensitive areas of the CCD
receiver.
p~ ~ ~
A virtual displacement of the illumination grid and the detector grid can be accomplished for example by disposing a plane-parallel plate between the illumination grid and the detector grid, said plate being pivotable around an axis which is perpendicular to the optical axis. In the embodiment with a lens array, two light sources can be located side by side. The virtual displacement then takes place by switching between the light sources.
The displacement of illumination and observation grids permits a periodic change between the stage of adjustment in which the light dots are imaged on photosensitive areas and the adjustment state in which the light dots are imaged on non-photo~ensitive intermediate spaces in the detector grid. Through the generation of a difference pixelwise, of two images recorded in the different states of adjustment in the computer, the confocal effect can then be intensified since the difference in the focused areas is especially great and is especially small in the defocused object area~.
For a depth of field which is as small as possible in the confocal image, it is advantageous instead of the usual circular telecentric diaphragm to provide an annular diaphragm. The u~e of such a diaphragm i5 known from EP-A2 0 244 640. In the latter, diaphragms with other transmission pattern~ are described which are also suitable for the ~re~ent optical ima~ing system in 2~ 8 order to adjust the three-dimensional tran~mission function to the known object pattern.
The invention will now be described in greater detail with reference to the embodiments shown in Figures 1 to 8.
Figure 1 is an embodiment in which the illumination grid is created by an illuminated layer with holes;
Figure 2 is an embodiment in which the illumination of the holes is improved by an additional lens array:
Figure 3 is an embodiment in which the illumination grid i.
generated by a semiconductor array;
Figure 4 is a glass plate with a pattern for an inver~e illumination grid;
Figure 5 i~ an arrangement for generating an illumination grit by multiple imaging of a light source with a len~ array;
Figure 6 is an arrangement to generate an illumination grid by multiple imaging of an illuminated diaphragm with a lens array;
Figure 7 i~ an example of the illuminated diaphragm in Figure 6;
and .
2 ~ 2 ~
Figure 8 is an arrangement with a liquid crystal matrix aQ the illumination grid in transmitted light.
In Figure 1 (11) is a liqht source, for example a halogen lamp which, with the aid of condenser (llk) and po~sibly a filter (llf) (to filter out a sufficiently narrow region of the spectrum), illuminateq hole~ (121) in a layer (12s). A layer of this kind can be made in known fa~hion from chromium for example on a glass plate (12g). Holes (121) are arranged in layer (12s) in the same grid shape as the photosensitive areas of CCD
receiver (17). For example if receiver 1 CX 022 made by Sony is used, then the layer will have 512 x 512 holes 11 microns apart in both directions of the grid and with a hole qize of 2 microns x 2 microns for example. The si~e of the holes i8 therefore much ~maller than their spacing.
The illumination grid generated by illuminated holes (121) in layer (12s) lies in illumination plane (llb)~ The latter is imaged by lenses (130, 13u) in focal plane (13f) so that in the latter the object (14) is illuminated by light dot~ arranged in the form of a grid. The center-to-center spacing of the light dots is referred to as the illumination grid si~e. Xn the case of non-tran~parent objects, only surface (140) can be illuminated, while in transparent objects layer-q (14s) in~ide can also be illuminated by the light dot~. The light beams reflected by the object in focal plane (13f) are focu~ed by lenses (13u, 20~28 130) through a beam qplitter (16) in diaphragm plane (17b). The diaphragms required for confocal arrangement are produced in the diaphragm plane (17b? by the photo~ensitive areas of the CCD
receiver (17) whi~h are separated from one another by spaces that are larger than the photosensitive area~.
Between the len5es (130, 13u) a so-called telecentric diaphragm (13t) is usually located which ensures that the central beam (13m) strikes object (14~ parallel to optical axis (10), so that the position of the light dots on the object does not change when object (14) is moved in the direction of optical axis (10).
Object (14) can be moved by an adjusting device (15) in all three directions in space, so that different layers (14s~ of object (14) may be scanned. The movement in the x and y direction~ can be made smaller than the grid size of light dots (12) or of CCD
receiver (17). of course the movement of object (14) in the &
direction can also be achieved by displacement of lenses (130, 13u) in the direction of optical axis (10) and likewise instead of moving the object in the x and y directions, layer (12s) can be moved accordingly together with holes (121) and CCD receiver (17).
The signals from CCD receiver (17) are transmitted through connecting lead (17v) to a computer (18) which handles evaluation and show~ the result.Q of the evaluation, for example in the form .
2 ~ 8 of graphs, on a screen (18b). Computer (18) can also control the displacement of focal ~lane (13f) in the object and ~canning in the x and y directions through connecting lead (18v). This control can be present in the computer as a fixed program or can depend on the results of the evaluation.
In Figure 2 a len~ array (22a) is located between condenser (llk) and filter (llf) and layer (12s) with holes (121), said array having the same number of small lenses (221) as layer 1129) has holes (121). Lenses (221) have the task of imaging images of the helix of light from light source (11) in the holes and thus giving the light dots greater intensity.
Lens array (22a) and layer (12g) with holes (121) can, a~ shown, be combined into a common part (22g). The manufacture of suitable lens arrays is known for example from a publication by X. Roizumi (SPIE, Vol. 1128, 74 (1989)).
An especially advantageous embodiment of the illumination grid is shown in Figure 3. In this figure, (31) refers to a light source array which can consi~t for example of light-emitting diodes (LEDs) (311). An array of this kind measuring for example 10 x 10 diodes can be assembled for example from commercial Siemens LSU260-EO minidiode~, with the diodes ~paced 2.5 mm apart, and therefore has a total size of 2.5 cm x 2.5 cm. On a scale of approximately 1:5 it is imaged in the illumination plane (llb) by . ., ; .
2~ 2 ~
lens (310) in such a way that the image of the illumination grid occupie~ in the plane of the CCD receiver almost the same ~ize a-q the entire photosenqitive area of the CCD receiver namely 5 mm x S mm. CCD receiver tl7~ in this case utilizes only 100 photosen~itive areas with a ~pacing of approximately 0.5 mm x 0.5 mm of the total available 512 x 512 detector elements.
Nevertheless, the 100 light dot~ produce a con~iderable gain in time over scanning with only one light dot.
In this case also it can be advantageous to dispose a layer (32g) with holes (321) in illumination plane (llb) 50 that the light dotq have sufficiently ~mall dimensions. Apart from lens (310) for the reduced image, a field lens (31f) is advantageou~ for further imaging in the confocal beam path.
With a piezo drive (15v) layer (32g) can be di~placed perpendicularly to the optical axis in the x and/or y direction 90 that alternately holes (321) are imaged on photosensitive areas and on nonphotosensitive intervalQ of CCD aamera t17). In computer (18), then the difference of the light inten-qity of two images taken side by -~ide is then calculated pixel by pixel. An increased confocal effect can be achieved in this manner.
It is much more advantageous to u3e integrated LED array~ for the illumination grid like tho~e described for example in a publication by J. P. Donnelly (SPIE 1043, 92 (1989)). LED array~
2 ~ 2 ~
of this ~ind, exactly like the array a~sembled from mini diodes, have the advantage that ~pecific partial quantities of the LEDs can be turned off and on. In both cases the turning on and off is controlled by the computer (18) through switching device (19).
The confocal beam path shown in Figures 1 to 3 between llumination plane (llb), focal plane (13f) and diaphragm plane (17b) is only a special embodiment of a plurality of known confocal beam paths in which the invention can be used in a manner which is immediately obvious to the indlvidual skilled in the art. In addition, in the beam path shown, an image of illumination plane (llb) in focal plane ~13f) on a 1:1 scale i5 not necessary. Instead not only (as known from micro3copes) is a reduction possible but an increase as well, for which reason the term microscope was not used in the title.
Figure 4 shows a glass plate (41) for an inverse illumination grid. Here the layer mounted on the glass plate and not permeable to light consists only of small zones (42) which are separated from one another by relatively broad translucent areas.
In Figure 5, the illumination grid ~s generated by a lens array (53) which, as a result of the outstandingly good imaging properties of a nearly punctate light source (51), produces a n~mber of sufficiently small light dots (54) in illumination plane (llb). Condenser lens (52) ensures that lens array (53) is 2 ~
traverqed by a parallel beam, ~o that each individual lens (531) is optimally u~ed.
Figure 6 shows an arrangement in which, by means of a lens array (53), a diaphragm (61) i~ imaged several times in illumination ~lane ~llb). This diaphragm i3 illuminated throu~h condenser (62) and scattering disk (63) by light source (11). A wide variety of embodiments is possible for the diaphragm. For example Figure 7 shows a diaphragm (61) with a square boundary for translucent area (71) and an opaque center (72) for an inverse illumination grid. Of course, diaphragms for an illumination grid made of light dots, etc. is al~o pos~ible.
In the embodiment shown in Figure 8 a confocal grid micro~cope is uced. It contains, as the illumination grid, a liquid crystal display (83). The transmission of the partial areas (83a-i) of the liquid crystal display, of which only partial areas are qhown here, is addressably variable by an electronic switching device (97).
Liquid cry~tal display (83) is illuminated from the rear by a light source (81) and a collector (82). Illumination grid (83) is imaged, reduced, in focal plane (87) by an intermediate lens (84) and a condenser (85). The entrance pupil (85b) o~ the condenser 3erves a~ a telecentering diaphragm here.
: '. . :. .' .
2 ~ 2 8 As far as observation is concerned, the image of the liquid crystal display located in focal plane (87) is imaged by a len~
(88) and a tube len~ (90) telecentrically on a CCD receiver (91).
Here exit pupil (88b) of lens (88) serves as a telecentering diaphragm.
The images recorded by CCD receiver (91) are read after digitization in an analog/digital converter into a computer (94) and processed.
In the case ill~strated, only two partial areas (83a, 83e) of liquid crystal display (83) are switched to high transmission.
Accordingly, in focal plane (87) only two light spots are generated and only the two detector element~ (9la, 91e), which are assigned to the two partial area~ (83a, 83e) imagewise, receive scattered light in ~ocal plane (87). The remaining detector elements (91b-d, 91f-i) act as confocal diaphragms with their ~ignals being not considered or considered separately in the expansion of the i.mage.
Object (14) can now be scanned in focal plane (87) by virtue of the fact that partial areas which differ from one another (83a-i) of liquid crystal display (83) or different combinations of partial areas (83a-i) are switched to high transmiss10n and then the signals from detector elements ~9la-i) a~-~ociated with partial areas (83a-i) that have been switched on are taken into : - :
2 ~ 2 8 account in the evaluation. For thi~ addre~ able control of partial areas (83a-i), computer (94) is connected to 3witching device (97). The total image which is then a~embled from a plurality of individual images is then displayed on a monitor (95).
Furthermore, object table (86) i~ displaceable oy a control device (98), itself controlled in turn by computer (94), in three mutually perpendicular directions in space. Through delicate displacement of object table (86) parallel to focal plane (87), images with a very high latent re~olution can be recorded. The displacement of object table (86) parallel to the optical axis serves to record different depth slices of object (14).
In this embodiment only the dete¢tor grid si~e, in other words the center-to-center distance of detector elements (9la-i), i~
fixed. On the other hand, the illumination grid si~e in the focal plane can be varied by computer (94) and switching device (97) and depends on how many partlal areas (83a-i) o~ display (83) are simultaneously switched to high transmission. Therefore the confocal effect can vary as a function of the measurement conditions. Thus for example, to generate overviews, all the partial areas (83a-i) can be switched to high transmis~ion. The image recorded by CCD sensor (91) then correspond~ to a normal bright-field image. ~owever it i~ also possible to adjust the different distances of the partial areas (83a-i) that sre switched to high transmission. In this case the confocal e~ Q~ ~ ~2 8 varies within the image field.
In Figure 8, for reasons of clarity, only nine partial areas (83a-i~ of the display and nine associated detector elements (9la-i) are shown. It is clear that both the display and the receiver (91) can have many more two-dimensionally arranged partial areas or detector elements.
In the embodiments described with reference to the drawings the light always has the same wavelength as far as illumination and observation are concerned. The device according to the invention can however also be used advantageously for fluorescence measurements. For this purpose, suitable color filters can be placed in front of the detector grid which pass only the fluorescent light from the object and block the light projected onto the object.
-' .' , ' , .:
...~
ODtical Device With Confocal Beam Path For Three-Dimensional Examination of an Obiect The present invention relates to a devics for three-di~ensional examination of an object according to the preamble of Claim 1.
A device in the form of a confocal scanning microscope is described in a publication by D. ~. Hamilton, et al. (Appl. Phy~.
B 27, 211 (1982)). Scanning micro~copes with confocal beam paths, in which a so-called point light source is imaged on a plane of the object and this plane of the object is imaged on a so-called ~pot receiver or hole diaphragm behind which a receiver is located, have the property of being very height-~elective, in other words of optically separating planes that are only a short distance apart. In the above publication, this property i9 u~ed to record a curface profile of a ~emiconductor component. For this purpose, for each x-y po~ition of the light spot, the object i~ moved in the z direction (direction of the optical axis) and the intensity curve i9 mea-cured. Since the latter has a pronounced maximum when the image of the light ~pot is located precisely on the surface, the height of the surface in the z direction can be determined for every point in the x-y plane and the entire surface profile of the object can be recorded ~equentially in this manner as a function of time.
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20~2~
One disadvantage of this known device is that the recording of a surface profile requires a relatively long time since only one individual object point is scanned at each point in time.
Moreover, a confocal microscope is known from U.S. Patent 4,407,008 in which a one~`or two-dimensional luminou~ diode array is imaged in the object plane. The light scattered or reflected at the object ~urface is then imaged on a one-dimensional or two-dimensional detector diode array. Thi~ microscope permits scanning an object without deflecting the light beam mechanically or moving the object, but here again only a single small area of the object is illuminated at each point in time so that once again a relatively long time is required to record a surface profile.
The goal of the pre3ent invention is to provide a device by which three-dimensional optical examinations can be conducted in a relatively short time.
The stated goal is achieved according to the invention by a device w1th the features of Claim 1.
In the device according to the invention, the il-lumination grid simultaneou~ly produces a plurality of separate light ~pot~ ~n the focal plane so that a correspondingly large number of object point~ can be measured simultaneou~ly. The d1~tanc~ between the 2 ~
light spots, in other word~ the illumination grid si~e, roughly corre~ponds to t~o to ten times their diameter. This illumination grid scale is either imaged on the detector grid in such a way that the image of the illumination grid size i~
greater than the detector grid ~ie or the detector grid is larger than the diameter or edge lengths of the photo~ensitive surfaceq of the individual detector elements. In both alternative embodimentq, the detector grid simultaneou~ly serves as the detector and confocal grid. In the first case, the detector elements which in the ca~e of a plane object are located in the focal plane between ~sic] the image of the illumination grid, as a diaphragm, while the output signals from these detectors are not taken into account in the second evaluation.
In the second case the photosensitive areas between the detector elements act as confocal diaphragms.
It has been found that commercial CCD receivers are best suited a~ detector grids. The generally disadvantageous property of the~e ~ensors can then be put to use, namely that only a small part of the receiver surface con~ists of photosensitive areas.
The distance between the individual detector elements is then about five to 9iX times their diameter.
The use of a CCD receiver and a two-dimensional array of holes in an illuminated layer is known to be used in a scanning micro~cope according to U.S. Patent 4,806,00~. However, that patent merely 2 ~
states that the object can be observed in different layer planes.
In particular, the diaphragm effect of the CCD receiver is not utili~ed, namely the fact that it consi-Yts of photosensitive area~ arranged in a grid, whose dimensions are much smaller than their distances apart.
In the above-captioned U.S. Patent, the confocal beam path is used only in an incident light microscope in which the beams that travel to the object pass through the same hole array as the beams reflected from the object. It i5 therefore neaessary to use an optical element referred to as an ocular to image the hole array in a plane in which it is ob~erved or recorded. For the latter case, a video camera with a CCD receiver is mentioned, whose images can be stored and evaluated.
In the present invention on the other hand, the grid-~haped arrangement of the detector element3 of ths detector grid is u~ed.
In contrast to the above-cited publication of Hamilton and the micro cope known from U.S. Ratent 4,407,008, the solution according to the invention not only has the advantage that recording of a surface profile proceeds much more rapidly because of the simultaneous illumination of a plurality of object points, but a height-selective observation i-q al~o directly pos~ible, sinee the confocal beam ~ath means that the intensity of the 2Q~2~
radiation reflected from the individual object ~oints depends directly on the heights of the location-q in the object in question, so that each grid element provides information about the height of the surface at its point in the object and hence the inten~ity distribution over the surface provides a direct overview of the height distribution of the object surface. In particular, when the object is moved relative to the beam path in the direction of the optical axis, the areas with the same surface height can be determined very simply.
In objects with reflecting areas in or under a transparent layer, reflection profiles with a small maximum for the ~urface of the transparent layer and a large maximum for the re~lecting area are obtained to show the dependence of intensity on depth in the object. Therefore it i~ possible with the device according to the invention to in~estigate not only surface profile~ but also ~tructures within or under transparent layers.
In one advantageous simple embodiment of the invention, the illumination grid is produced by holes in a layer which is illuminated by a light source. In order to achieve a higher intensity for the illuminated holes, hereinafter referred to as light dots for short, a lens array can be disposed in front of the layer with the holes, said array servin~ to ensure that the radiation from the light ~ource does not illuminate the layer uniformly but is concentr~ted on the holes.
2 ~
Normally the CCD receiver and the illumination grid are adjusted to one another in ~uch fashion that the light dots imaged on the plane of the detector grid fall on photosensitive areas of the CCD receiver. In this case, durin~ focusing, intensity ma~ima are obtained for those object points whose reflecting ~urfaces lie exactly in the focal plane.
It i5 al~o pos~ible however to adju~t the CCD receiver and the illumination grid with respect to one another in ~uch fashion that the light dots imaged in the plane of the CCD receiver fall between the photosensitive areas of the CCD recsiver. In this case, during focusing, intensity minima are created for those object points whose reflecting ~urface3 lie precisely in the focal plane. With a special design for the CCD receiver, for example with relatively small-area non-photo~ensitive area~
between the pixels, this effect can be reinforced even further.
Finally, an inverse illumination grid i9 also possible; in other words the grid imaged in the focal plane and in the plane conjugate to the focal plane doe~ not con~i~t of bright light dots but of a bright surface with a grid-shaped arrangement of small dark zones. An illumination grid of this kind, which con~ist~ for example of a layer illuminated by the light source with nontranslucent zones, in the case of a CCD receiver ~ith small photo~en3itive areaa on which the dark ~one are imaged, 2Q~2~
likewise yields intensity minima for those object points whose reflecting surfaces lie preci~ely in the focal plane.
In another advantageous embodiment, the illumination grid is produced by a lens array which images an approximately punctate light source several times in a grid-shaped arrangement in an illumination plane.
In another advantageous embodiment~ the illumination grid is produced by the fact that a diaphragm illuminated by a light source is imaged several times in a grid-shaped arrangement in an illumination plane. In this case also, an inverse illumination grid can be produced for example by virtue of the fa~t that the diaphragm has a center which is not transluoent.
In an e~pecially advantageous embodiment, the illumination grid is produced by a light source array. This can be composed for e~ample of individual LEDs or produced by integrated technology.
In both cases it is especially advantageous to design the array~
and their voltage supply in such a way that either each individual light source or a certain number of the light sources can be turned on and off independently of the others. The si~e of the illumination grid can then be varied and~different depth resolutions can be set.
20~92~
A variable illumination grid can also be produced by making the transmission of partial areas of the illumination grid variable.
In addition, the illumination grid can be a liquid crystal matrix illuminated from behind.
To record the height-selective overview described above, it is advantageous to provide an adjusting device which makes it possible to adjust the focal plane with the images of the light dots at different layer depths in the ob~ect.
To record complete reflection profiles with good resolution it is advantageous to provide an adjusting device which makes it possible to move the illumination grid and the object relative to one another in planes perpendicular to the optical a~is so that the object is scanned with the illumination grid. The relative movement between the light dots and the object can then remain within the spacing of adjacent light dots or can be a multiple thereof. When using a variable illumination grid, rough scanning of the object can be performed on partial areas of the illumination grid that differ as a result of sequential switching.
In another advantageous embodiment of the invention the CCD
receiver is connected to a computer which evaluates the 3ignals from the CCD receiver. In this case it is advantageous to control the adjusting device~ for the relative movement of light 2 ~ 2 ~
dots and the object with respect te one another in the direction of the optical axiQ and/or in the planeQ of the li~ht dots or the object ~y using the computer.
In an especially preferred embodiment of the invention, a ~witching device is likewiQe controlled by the computer which turns different partial quantities of the light ~ources in the light source array on and off, or varies the tran~mission of different partial areas of the illumination grid. ThuY for example the number of light sources that are switched on can be controlled by the re~ults of the evaluation of the computer so that in critical areas of an object the amount of scattered light can be reduced by reducing the number of effective light ~ources.
It may be advantage~u~ when scanning an object to di~place the illumination grid really or virtually in the CCD receiver relative to one another in the illumination plane or in the plane of the diaphragm by a switching or adjusting device, which i~
advantageously controlled by the computer. By using a powerful computer, additional information can be obtained by this displacement which permits a more accurate evaluation. In this case, the grid ~ize of the illumination grid should be larger than the grid size of the photosensitive areas of the CCD
receiver.
p~ ~ ~
A virtual displacement of the illumination grid and the detector grid can be accomplished for example by disposing a plane-parallel plate between the illumination grid and the detector grid, said plate being pivotable around an axis which is perpendicular to the optical axis. In the embodiment with a lens array, two light sources can be located side by side. The virtual displacement then takes place by switching between the light sources.
The displacement of illumination and observation grids permits a periodic change between the stage of adjustment in which the light dots are imaged on photosensitive areas and the adjustment state in which the light dots are imaged on non-photo~ensitive intermediate spaces in the detector grid. Through the generation of a difference pixelwise, of two images recorded in the different states of adjustment in the computer, the confocal effect can then be intensified since the difference in the focused areas is especially great and is especially small in the defocused object area~.
For a depth of field which is as small as possible in the confocal image, it is advantageous instead of the usual circular telecentric diaphragm to provide an annular diaphragm. The u~e of such a diaphragm i5 known from EP-A2 0 244 640. In the latter, diaphragms with other transmission pattern~ are described which are also suitable for the ~re~ent optical ima~ing system in 2~ 8 order to adjust the three-dimensional tran~mission function to the known object pattern.
The invention will now be described in greater detail with reference to the embodiments shown in Figures 1 to 8.
Figure 1 is an embodiment in which the illumination grid is created by an illuminated layer with holes;
Figure 2 is an embodiment in which the illumination of the holes is improved by an additional lens array:
Figure 3 is an embodiment in which the illumination grid i.
generated by a semiconductor array;
Figure 4 is a glass plate with a pattern for an inver~e illumination grid;
Figure 5 i~ an arrangement for generating an illumination grit by multiple imaging of a light source with a len~ array;
Figure 6 is an arrangement to generate an illumination grid by multiple imaging of an illuminated diaphragm with a lens array;
Figure 7 i~ an example of the illuminated diaphragm in Figure 6;
and .
2 ~ 2 ~
Figure 8 is an arrangement with a liquid crystal matrix aQ the illumination grid in transmitted light.
In Figure 1 (11) is a liqht source, for example a halogen lamp which, with the aid of condenser (llk) and po~sibly a filter (llf) (to filter out a sufficiently narrow region of the spectrum), illuminateq hole~ (121) in a layer (12s). A layer of this kind can be made in known fa~hion from chromium for example on a glass plate (12g). Holes (121) are arranged in layer (12s) in the same grid shape as the photosensitive areas of CCD
receiver (17). For example if receiver 1 CX 022 made by Sony is used, then the layer will have 512 x 512 holes 11 microns apart in both directions of the grid and with a hole qize of 2 microns x 2 microns for example. The si~e of the holes i8 therefore much ~maller than their spacing.
The illumination grid generated by illuminated holes (121) in layer (12s) lies in illumination plane (llb)~ The latter is imaged by lenses (130, 13u) in focal plane (13f) so that in the latter the object (14) is illuminated by light dot~ arranged in the form of a grid. The center-to-center spacing of the light dots is referred to as the illumination grid si~e. Xn the case of non-tran~parent objects, only surface (140) can be illuminated, while in transparent objects layer-q (14s) in~ide can also be illuminated by the light dot~. The light beams reflected by the object in focal plane (13f) are focu~ed by lenses (13u, 20~28 130) through a beam qplitter (16) in diaphragm plane (17b). The diaphragms required for confocal arrangement are produced in the diaphragm plane (17b? by the photo~ensitive areas of the CCD
receiver (17) whi~h are separated from one another by spaces that are larger than the photosensitive area~.
Between the len5es (130, 13u) a so-called telecentric diaphragm (13t) is usually located which ensures that the central beam (13m) strikes object (14~ parallel to optical axis (10), so that the position of the light dots on the object does not change when object (14) is moved in the direction of optical axis (10).
Object (14) can be moved by an adjusting device (15) in all three directions in space, so that different layers (14s~ of object (14) may be scanned. The movement in the x and y direction~ can be made smaller than the grid size of light dots (12) or of CCD
receiver (17). of course the movement of object (14) in the &
direction can also be achieved by displacement of lenses (130, 13u) in the direction of optical axis (10) and likewise instead of moving the object in the x and y directions, layer (12s) can be moved accordingly together with holes (121) and CCD receiver (17).
The signals from CCD receiver (17) are transmitted through connecting lead (17v) to a computer (18) which handles evaluation and show~ the result.Q of the evaluation, for example in the form .
2 ~ 8 of graphs, on a screen (18b). Computer (18) can also control the displacement of focal ~lane (13f) in the object and ~canning in the x and y directions through connecting lead (18v). This control can be present in the computer as a fixed program or can depend on the results of the evaluation.
In Figure 2 a len~ array (22a) is located between condenser (llk) and filter (llf) and layer (12s) with holes (121), said array having the same number of small lenses (221) as layer 1129) has holes (121). Lenses (221) have the task of imaging images of the helix of light from light source (11) in the holes and thus giving the light dots greater intensity.
Lens array (22a) and layer (12g) with holes (121) can, a~ shown, be combined into a common part (22g). The manufacture of suitable lens arrays is known for example from a publication by X. Roizumi (SPIE, Vol. 1128, 74 (1989)).
An especially advantageous embodiment of the illumination grid is shown in Figure 3. In this figure, (31) refers to a light source array which can consi~t for example of light-emitting diodes (LEDs) (311). An array of this kind measuring for example 10 x 10 diodes can be assembled for example from commercial Siemens LSU260-EO minidiode~, with the diodes ~paced 2.5 mm apart, and therefore has a total size of 2.5 cm x 2.5 cm. On a scale of approximately 1:5 it is imaged in the illumination plane (llb) by . ., ; .
2~ 2 ~
lens (310) in such a way that the image of the illumination grid occupie~ in the plane of the CCD receiver almost the same ~ize a-q the entire photosenqitive area of the CCD receiver namely 5 mm x S mm. CCD receiver tl7~ in this case utilizes only 100 photosen~itive areas with a ~pacing of approximately 0.5 mm x 0.5 mm of the total available 512 x 512 detector elements.
Nevertheless, the 100 light dot~ produce a con~iderable gain in time over scanning with only one light dot.
In this case also it can be advantageous to dispose a layer (32g) with holes (321) in illumination plane (llb) 50 that the light dotq have sufficiently ~mall dimensions. Apart from lens (310) for the reduced image, a field lens (31f) is advantageou~ for further imaging in the confocal beam path.
With a piezo drive (15v) layer (32g) can be di~placed perpendicularly to the optical axis in the x and/or y direction 90 that alternately holes (321) are imaged on photosensitive areas and on nonphotosensitive intervalQ of CCD aamera t17). In computer (18), then the difference of the light inten-qity of two images taken side by -~ide is then calculated pixel by pixel. An increased confocal effect can be achieved in this manner.
It is much more advantageous to u3e integrated LED array~ for the illumination grid like tho~e described for example in a publication by J. P. Donnelly (SPIE 1043, 92 (1989)). LED array~
2 ~ 2 ~
of this ~ind, exactly like the array a~sembled from mini diodes, have the advantage that ~pecific partial quantities of the LEDs can be turned off and on. In both cases the turning on and off is controlled by the computer (18) through switching device (19).
The confocal beam path shown in Figures 1 to 3 between llumination plane (llb), focal plane (13f) and diaphragm plane (17b) is only a special embodiment of a plurality of known confocal beam paths in which the invention can be used in a manner which is immediately obvious to the indlvidual skilled in the art. In addition, in the beam path shown, an image of illumination plane (llb) in focal plane ~13f) on a 1:1 scale i5 not necessary. Instead not only (as known from micro3copes) is a reduction possible but an increase as well, for which reason the term microscope was not used in the title.
Figure 4 shows a glass plate (41) for an inverse illumination grid. Here the layer mounted on the glass plate and not permeable to light consists only of small zones (42) which are separated from one another by relatively broad translucent areas.
In Figure 5, the illumination grid ~s generated by a lens array (53) which, as a result of the outstandingly good imaging properties of a nearly punctate light source (51), produces a n~mber of sufficiently small light dots (54) in illumination plane (llb). Condenser lens (52) ensures that lens array (53) is 2 ~
traverqed by a parallel beam, ~o that each individual lens (531) is optimally u~ed.
Figure 6 shows an arrangement in which, by means of a lens array (53), a diaphragm (61) i~ imaged several times in illumination ~lane ~llb). This diaphragm i3 illuminated throu~h condenser (62) and scattering disk (63) by light source (11). A wide variety of embodiments is possible for the diaphragm. For example Figure 7 shows a diaphragm (61) with a square boundary for translucent area (71) and an opaque center (72) for an inverse illumination grid. Of course, diaphragms for an illumination grid made of light dots, etc. is al~o pos~ible.
In the embodiment shown in Figure 8 a confocal grid micro~cope is uced. It contains, as the illumination grid, a liquid crystal display (83). The transmission of the partial areas (83a-i) of the liquid crystal display, of which only partial areas are qhown here, is addressably variable by an electronic switching device (97).
Liquid cry~tal display (83) is illuminated from the rear by a light source (81) and a collector (82). Illumination grid (83) is imaged, reduced, in focal plane (87) by an intermediate lens (84) and a condenser (85). The entrance pupil (85b) o~ the condenser 3erves a~ a telecentering diaphragm here.
: '. . :. .' .
2 ~ 2 8 As far as observation is concerned, the image of the liquid crystal display located in focal plane (87) is imaged by a len~
(88) and a tube len~ (90) telecentrically on a CCD receiver (91).
Here exit pupil (88b) of lens (88) serves as a telecentering diaphragm.
The images recorded by CCD receiver (91) are read after digitization in an analog/digital converter into a computer (94) and processed.
In the case ill~strated, only two partial areas (83a, 83e) of liquid crystal display (83) are switched to high transmission.
Accordingly, in focal plane (87) only two light spots are generated and only the two detector element~ (9la, 91e), which are assigned to the two partial area~ (83a, 83e) imagewise, receive scattered light in ~ocal plane (87). The remaining detector elements (91b-d, 91f-i) act as confocal diaphragms with their ~ignals being not considered or considered separately in the expansion of the i.mage.
Object (14) can now be scanned in focal plane (87) by virtue of the fact that partial areas which differ from one another (83a-i) of liquid crystal display (83) or different combinations of partial areas (83a-i) are switched to high transmiss10n and then the signals from detector elements ~9la-i) a~-~ociated with partial areas (83a-i) that have been switched on are taken into : - :
2 ~ 2 8 account in the evaluation. For thi~ addre~ able control of partial areas (83a-i), computer (94) is connected to 3witching device (97). The total image which is then a~embled from a plurality of individual images is then displayed on a monitor (95).
Furthermore, object table (86) i~ displaceable oy a control device (98), itself controlled in turn by computer (94), in three mutually perpendicular directions in space. Through delicate displacement of object table (86) parallel to focal plane (87), images with a very high latent re~olution can be recorded. The displacement of object table (86) parallel to the optical axis serves to record different depth slices of object (14).
In this embodiment only the dete¢tor grid si~e, in other words the center-to-center distance of detector elements (9la-i), i~
fixed. On the other hand, the illumination grid si~e in the focal plane can be varied by computer (94) and switching device (97) and depends on how many partlal areas (83a-i) o~ display (83) are simultaneously switched to high transmission. Therefore the confocal effect can vary as a function of the measurement conditions. Thus for example, to generate overviews, all the partial areas (83a-i) can be switched to high transmis~ion. The image recorded by CCD sensor (91) then correspond~ to a normal bright-field image. ~owever it i~ also possible to adjust the different distances of the partial areas (83a-i) that sre switched to high transmission. In this case the confocal e~ Q~ ~ ~2 8 varies within the image field.
In Figure 8, for reasons of clarity, only nine partial areas (83a-i~ of the display and nine associated detector elements (9la-i) are shown. It is clear that both the display and the receiver (91) can have many more two-dimensionally arranged partial areas or detector elements.
In the embodiments described with reference to the drawings the light always has the same wavelength as far as illumination and observation are concerned. The device according to the invention can however also be used advantageously for fluorescence measurements. For this purpose, suitable color filters can be placed in front of the detector grid which pass only the fluorescent light from the object and block the light projected onto the object.
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Claims (21)
1. Device for three-dimensional examination of an object - with an illumination grid, - a detector grid which consists of a plurality of independent detectors, whose center-to-center distances constitute a detector grid size;
- optical elements to image the illumination grid in a focal plane and to image the focal plane on the detector grid, characterized by the fact that - illumination grid (12; 22; 31; 83) generates several separate light spots or shadow zones simultaneously in focal plane (13f; 87), whose center-to-center distances constitute an illumination grid size, and - that either the image of the illumination grid size in the plane of detector grid (17; 91) is larger than the detector grid size or the detector grid-size is larger than the diameters and/or edge lengths of the photosensitive surfaces of the individual detector elements.
- optical elements to image the illumination grid in a focal plane and to image the focal plane on the detector grid, characterized by the fact that - illumination grid (12; 22; 31; 83) generates several separate light spots or shadow zones simultaneously in focal plane (13f; 87), whose center-to-center distances constitute an illumination grid size, and - that either the image of the illumination grid size in the plane of detector grid (17; 91) is larger than the detector grid size or the detector grid-size is larger than the diameters and/or edge lengths of the photosensitive surfaces of the individual detector elements.
2. Device according to Claim 1 characterized by the fact that the detector grid size corresponds to at least twice the diameter or edge length of the photosensitive area of the individual detector elements.
3. Device according to Claim 1 or 2 characterized by the fact that the detector grid size is a CCD sensor (17; 91).
4. Device according to one of Claims 1 to 3 characterized by the fact that the image of the illumination grid size in the plane of detector grid (17; 91) at least corresponds to twice the detector grid size.
5. Device according to one of Claims 1 to 4 characterized by the fact that illumination grid (12) consists of holes (121) in a layer (12-s), illuminated by a light source (11).
6. Device according to Claim 5 characterized by the fact that a lens array (22a) is provided for illuminating holes (121).
7. Device according to one of Claims 1 to 4 characterized by the illumination grid consisting of a layer of opaque zones (42) illuminated by a light source (11).
8. Device according to one of Claims 1 to 4 characterized by the fact that the illumination grid is generated by a lens array (53) which images a light source (51) several times in a grid arrangement on an illumination plane (11b).
9. Device according to one of Claims 1 to 4 characterized by the fact that the illumination grid is generated by a lens array (53) which imaged a diaphragm (61) illuminated by a light source (11) several times in a grid-shaped arrangement on an illumination plane (11b).
10. Device according to Claim 9 characterized by the fact that diaphragm (61) has an opaque center (72).
11. Device according to one of Claims 1 to 4 characterized by the illumination grid size being variable.
12. Device according to Claim 11 characterized by the illumination grid containing a light source array (31).
13. Device according to Claim 12 characterized by the light sources (311) of light source array (31a) being capable of being turned on or off individually or in partial numbers.
14. Device according to Claim 11 characterized-by the transmission of partial areas (83a-i) of illumination grid (83) being variable individually or in partial numbers.
15. Device according to one of Claims 11 to 14 characterized by an electronic switching device (19; 97) being provided to vary the size of the illumination grid.
16. Device according to one of Claims 1 to 15 characterized by focal plane (13f) being adjustable to various layers (14s) of object (14) through an adjusting device (15; 98) and/or illumination grid (12; 22; 31; 83) and object (14) being movable relative to one another in planes perpendicular to optical axis (10).
17. Device according to one of Claims 1 to 16 characterized by the fact that CCD receiver (17; 91) is connected with a computer (18; 94) in which the signals of CCD receiver (17; 91) are evaluated.
18. Device according to Claim 17 characterized by computer (18;
94) being connected with an adjusting device (15; 98), by which the adjustment of focal plane (13f; 87) on various layers (14s) of object (14) and/or the movement of illumination grid (12; 22;
31; 83) and object (14) relative to one another is controllable by computer (18; 94).
94) being connected with an adjusting device (15; 98), by which the adjustment of focal plane (13f; 87) on various layers (14s) of object (14) and/or the movement of illumination grid (12; 22;
31; 83) and object (14) relative to one another is controllable by computer (18; 94).
19. Device according to Claim 17 or 18 characterized by the fact that computer (18; 94) is connected with switching device (19;
97), by which light sources (131; 83a-i) of light source array (31a; 83) can be switched on and off individually or in partial numbers as a function of the result of the computer evaluation, by the computer (18; 94).
97), by which light sources (131; 83a-i) of light source array (31a; 83) can be switched on and off individually or in partial numbers as a function of the result of the computer evaluation, by the computer (18; 94).
20. Device according to one of Claims 17 to 19 characterized by computer (18) being connected with a switching or adjusting device (15v), by which illumination grid (12; 22; 31) and the CCD
receiver (17) are displaceable relative to one another in their respective planes.
receiver (17) are displaceable relative to one another in their respective planes.
21. Device according to one of Claims 1 to 20 characterized by the fact that a telecentric diaphragm (13t) is provided in the confocal beam path, said diaphragm being made annular and/or having a transmission pattern.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP4035799.6-42 | 1990-11-10 | ||
| DE19904035799 DE4035799C2 (en) | 1990-11-10 | 1990-11-10 | Device for three-dimensional optical examination of an object |
| US62667890A | 1990-12-12 | 1990-12-12 | |
| US07/626,678 | 1990-12-12 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2054928A1 true CA2054928A1 (en) | 1992-05-11 |
Family
ID=25898384
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002054928A Abandoned CA2054928A1 (en) | 1990-11-10 | 1991-11-05 | Optical device with confocal beam path |
Country Status (5)
| Country | Link |
|---|---|
| EP (1) | EP0485803B1 (en) |
| JP (1) | JPH04265918A (en) |
| AT (1) | ATE137588T1 (en) |
| CA (1) | CA2054928A1 (en) |
| DE (1) | DE59107758D1 (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0533111U (en) * | 1991-10-14 | 1993-04-30 | 横河電機株式会社 | Confocal optical scan |
| JPH0533109U (en) * | 1991-10-14 | 1993-04-30 | 横河電機株式会社 | Confocal laser microscope |
| FR2707018B1 (en) * | 1993-06-22 | 1995-07-21 | Commissariat Energie Atomique | |
| JP2919776B2 (en) * | 1995-08-28 | 1999-07-19 | 横河電機株式会社 | Confocal microscope |
| US6104945A (en) * | 1995-08-01 | 2000-08-15 | Medispectra, Inc. | Spectral volume microprobe arrays |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3037983C2 (en) * | 1980-10-08 | 1983-03-31 | Fa. Carl Zeiss, 7920 Heidenheim | Method and device for the light-induced scanning microscopic representation of sample parameters in their spatial distribution |
| US4806004A (en) * | 1987-07-10 | 1989-02-21 | California Institute Of Technology | Scanning microscopy |
| US4802748A (en) * | 1987-12-14 | 1989-02-07 | Tracor Northern, Inc. | Confocal tandem scanning reflected light microscope |
-
1991
- 1991-10-30 DE DE59107758T patent/DE59107758D1/en not_active Expired - Lifetime
- 1991-10-30 EP EP91118461A patent/EP0485803B1/en not_active Expired - Lifetime
- 1991-10-30 AT AT91118461T patent/ATE137588T1/en active
- 1991-11-05 CA CA002054928A patent/CA2054928A1/en not_active Abandoned
- 1991-11-11 JP JP3294011A patent/JPH04265918A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| DE59107758D1 (en) | 1996-06-05 |
| JPH04265918A (en) | 1992-09-22 |
| EP0485803A1 (en) | 1992-05-20 |
| ATE137588T1 (en) | 1996-05-15 |
| EP0485803B1 (en) | 1996-05-01 |
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| Date | Code | Title | Description |
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| FZDE | Discontinued |