CN204202849U - A kind of CCD modulation transfer function measurement device - Google Patents
A kind of CCD modulation transfer function measurement device Download PDFInfo
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- CN204202849U CN204202849U CN201420560568.4U CN201420560568U CN204202849U CN 204202849 U CN204202849 U CN 204202849U CN 201420560568 U CN201420560568 U CN 201420560568U CN 204202849 U CN204202849 U CN 204202849U
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Abstract
The utility model discloses a kind of CCD modulation transfer function measurement device, this measurement mechanism comprises three-dimensional adjustment System, light source and light processing unit; Described smooth processing unit is fixed in three-dimensional adjustment System, and light processing unit comprises target slit and microcobjective; Described target slit and microcobjective are successively set on the emitting light path of described light source, and microcobjective comprises two faces, and one of them face is provided with screw thread, if threaded is image space, another face is object space; The emergent light of described light source is incident by image space, by object space outgoing.In the utility model, providing for obtaining line spread function the high imaging quality target slit that width is less than 1 μm, by reduce, the high-quality target slit obtained, this target slit being converged on tested image device array, achieve meticulous sampling, improve measuring accuracy.
Description
Technical field
The utility model belongs to field of optical detection, relates to a kind of CCD modulation transfer function measurement device and measuring method, the high precision modulation transfer function measurement device can set up for colored CCD.
Background technology
At present, the assay method of CCD transport function can be divided three classes, and a class pays close attention to structure and the electrology characteristic of CCD itself, from the physical model of CCD working mechanism, analyzes the physical process of CCD work, obtain the theoretical model of CCD transport function.More typically the people such as Ibrahima Djit of Toulouse, France university proposes the theoretical model of the CCD transport function that the steady state diffusion equation under a kind of sinusoidal light injection condition solves, this model needs electrical parameter when working to CCD material therefor, the structural parameters etc. of CCD measure, therefore the method realizes comparatively difficulty, only stays in laboratory stage at present.
The Orly Yadid-Pecht of Ben-Gu Li An university of Israel analyzes the shape of CCD photosensitive region to the impact of CCD transport function, give the CCD theoretical transfer function of difformity photosensitive area, this model only analyzes single pixel photosensitive region shape to the impact of CCD transport function, do not consider the impact on CCD transport function such as charge-conduction between CCD pixel, thus the directive significance that measures CCD transport function of this model is limited.
Another kind of is to be called target method, by passing through the change of this characteristic after CCD imaging to a certain ideal behavior of target and target, obtains CCD transport function.Laser speckle photography method and contrast method can be divided into according to the characteristic difference of target.
The nearest research of laser speckle photography method is the Alfred D.Ducharme of University of Central Florida, by the careful design of target producing laser speckle, creates the comparatively uniform laser speckle of power spectrum density, achieves the mensuration of the full target surface transport function of CCD.The quality requirements of the method to laser speckle is higher, and the curve of the CCD transport function obtained is level and smooth not.
In contrast method, different by the light transmission rate of desirable target plate, have again sinusoidal target and rectangular target point.Domestic, the Zhao Liefeng of Zhejiang University and the Hu Jiasheng of Dalian University of Technology etc. adopt laser interference principle to produce the adjustable sinusoidal interference striped of width of fringe respectively, by the mensuration to different in width sine streak contrast, obtain the transport function of CCD.The method needs the quality of sinusoidal interference striped higher, and phase matching precision is comparatively large on the impact of its test result, therefore complicated operation, the repeatability of test is poor.And there is the problem that target plate making is difficult and phase matching accuracy requirement is high equally in rectangular target.
3rd class methods are the analyses by counter blade limit diffraction image, obtain the transport function of CCD, therefore are often called recognition status.The method, by Fourier transform, achieves the analysis from spatial domain to frequency domain.In order to obtain the sample frequency higher than Qwest's frequency in CCD, making that sword limit is crossing with the row be made up of CCD pixel to have a certain degree, obtaining the edge function of up-sampling.By the inclination angle size on adjustment aim sword limit, the sampling interval of arbitrary size can be obtained in theory.Therefore IS012233 is using the standard method of inclination recognition status as the resolution test of electronic still image camera.The method, because sword edge image exists noise, needs complicated denoise algorithm.Algorithm principle also can introduce Algorithm Error because of the difference of difference and differential.The introducing at inclination angle, target sword limit can increase sample frequency on the one hand, also can introduce the error of calculation at inclination angle simultaneously and introduce the problem of frequency domain mismatch due to the sampling of CCD discrete quantized.In addition, the method needs by optical imaging system imaging, therefore needs to assess accurately the transport function of optical imaging system, and is deducted.
Said method cuts both ways, and front two class methods rest on laboratory stage substantially, cannot carry out engineer applied.3rd class algorithm is because the position of edge of a knife placement is different, and sword limit has corresponding diffraction effect, affects test result.General method is the most accurately close to CCD target surface to place the edge of a knife, completes the sampling of edge function, carry out difference, differential process subsequently, obtain modulation transfer function.Although it is so can be little as far as possible avoid because sword limit diffraction effect is on biography letter resultant impact; but due to the light-sensitive surface of CCD own last as all can have cover glass window (having color filter before colored CCD target surface); the edge of a knife can not be positioned over light-sensitive surface place, and diffraction effect and ghost image can produce considerable influence to the measurement result of modulation transfer function.
Utility model content
In order to solve the above-mentioned technical matters existed in background technology, the utility model provides a kind of CCD modulation transfer function measurement device.
Technical solution of the present utility model is:
A kind of CCD modulation transfer function measurement device, its special character is: comprise three-dimensional adjustment System, light source, light processing unit; Described smooth processing unit is fixed in three-dimensional adjustment System, and light processing unit comprises target slit and microcobjective; Described target slit and microcobjective are successively set on the emitting light path of described light source, between the light source that target slit is arranged and microcobjective; Microcobjective comprises two faces, and one of them face is provided with screw thread, if threaded is image space, another face is object space; The emergent light of described light source is incident by the image space of microcobjective, by the object space outgoing of microcobjective.
Above-mentioned smooth processing unit also comprises folding axle mirror and eyepiece, and folding axle mirror is arranged between microcobjective and target slit, and eyepiece is arranged on the top of folding axle mirror, makes, when rotating folding axle mirror, can see tested CCD light-sensitive surface by eyepiece.
Above-mentioned three-dimensional adjustment System comprises vertical electronic control translation stage, horizontal electronic control translation stage and front and back electronic control translation stage, horizontal electronic control translation stage is fixed on the electronic control translation stage of front and back, vertical electronic control translation stage is fixed on horizontal electronic control translation stage, vertical electronic control translation stage, mutually vertical between two between horizontal electronic control translation stage and front and back electronic control translation stage, described smooth processing unit is fixed on vertical electronic control translation stage.
The width of above-mentioned target slit is 1 ~ 2 times of tested CCD light-sensitive surface pixel width.
Above-mentioned CCD modulation transfer function measurement device also comprises control acquisition system; Described control acquisition system comprises light source control unit, direction of motion control module and collecting unit; Described light source control unit is connected with light source; Direction of motion control module is connected with front and back electronic control translation stage with vertical electronic control translation stage, horizontal electronic control translation stage respectively; Collecting unit is connected with tested CCD.
Above-mentioned control acquisition system also comprises the display unit be connected with tested CCD.
The utility model has the advantages that:
1, in the utility model, the emergent light of light source is incident by the image space of microcobjective, by the object space outgoing of microcobjective, creationary by reverse for microcobjective use, therefore, the utility model is anticaustic optical microscope system cleverly, provides for obtaining line spread function the high imaging quality target slit that width is less than 1 μm.By reduce, the high-quality target slit obtained, this target slit is converged on tested image device array, achieves meticulous sampling, improve measuring accuracy.
2, the vertical electronic control translation stage of the three-dimensional adjustment System of the utility model, horizontal electronic control translation stage and front and back electronic control translation stage, its positioning precision is better than 1 μm, thus can ensure the accuracy in scanning process, improves the accuracy of test result; Target slit can scan through tested CCD on vertical, front and back or horizontal direction.The fluctuation situation of the target image exported can be obtained by computer, and obtain line spread function (LSF), modulation transfer function can be calculated by line spread function.
3, smooth processing unit of the present utility model has also used folding axle mirror to coordinate with eyepiece, drafts the position of tested colored CCD image planes, subsequently by showing tested CCD modulation transfer function in real time, finally determines the best modulation transfer function of tested CCD.
4, the target slit used in the utility model, by light illuminating, by the microcobjective of a high imaging quality, target slit is imaged on tested CCD light-sensitive surface, the width of target slit is narrower than tested CCD light-sensitive surface pixel width, can obtain the line spread function that sampling is intensive, more meticulous like this.
5, measuring accuracy of the present utility model can reach ± 2%, measuring repeatability can reach ± 1%.
6, CCD modulation transfer function measurement device of the present utility model can complete the measurement to colored CCD modulation transfer function, especially can for the measurement respectively of colored CCD different spectral coverage (such as: RGB form) modulation transfer function, and go for the measurement of normal CCD modulation transfer function, be the testing apparatus that has wide range of applications, measuring accuracy is excellent.
Accompanying drawing explanation
Fig. 1 is structural representation of the present utility model;
Fig. 2 is the structural representation of three-dimensional adjustment System;
Wherein: 1-light source; 2-target slit; The three-dimensional adjustment System of 3-; The horizontal electronic control translation stage of 4-; The vertical electronic control translation stage of 5-; Electronic control translation stage before and after 6-; 8-microcobjective; 9-rolls over axle mirror; 10-eyepiece; The tested CCD of 11-; 12-controls acquisition system.
Embodiment
See Fig. 1, a kind of CCD modulation transfer function measurement device that the utility model provides, comprises three-dimensional adjustment System, light source 1, light processing unit; Light processing unit is fixed in three-dimensional adjustment System, and light processing unit comprises target slit 2 and microcobjective 8; Tested CCD11 comprises tested CCD light-sensitive surface; Target slit, microcobjective and tested CCD light-sensitive surface are successively set on the emitting light path of light source; Microcobjective comprises two faces, and one of them face is provided with installation screw thread, and being provided with the face of installing screw thread is image space, and another face is object space, and for microcobjective, the emergent light of light source is incident by the image space of microcobjective, by the object space outgoing of microcobjective.Three-dimensional adjustment System can make light processing unit in level, vertically, direction, three, front and back moves; Tested CCD imaging target surface (light-sensitive surface) is positioned at the image space plane place of reverse microscopic system (microcobjective).Target slit width is only 5 μm, after the reducing of microcobjective of the present utility model, target slit width is less than 1 μm, the follow-up extraction accuracy that can improve line spread function, and microcobjective can select the LMPLFLN-10 × model microcobjective of Olympus Corp.
Wherein, microcobjective can select flat field half apochromatic micro objective of high imaging quality, can obtain ideal slit target, improve the precision of measurement mechanism.
Light processing unit also comprises folding axle mirror 9 and eyepiece 10, and folding axle mirror is arranged in the light path between microcobjective and target slit, and eyepiece is arranged on the top of folding axle mirror, makes, when rotating folding axle mirror, can see tested CCD light-sensitive surface by eyepiece.Light path can be turned back 60 ° by folding axle mirror, conveniently checks the imaging contexts of target slit on tested CCD light-sensitive surface by eyepiece.Eyepiece can select the WHB10 × model eyepiece of Olympus Corp.
Three-dimensional adjustment System comprises vertical electronic control translation stage 5, horizontal electronic control translation stage 4 and front and back electronic control translation stage 6, horizontal electronic control translation stage is fixed on the electronic control translation stage of front and back, vertical electronic control translation stage is fixed on horizontal electronic control translation stage, vertical electronic control translation stage, mutually vertical between two between horizontal electronic control translation stage and front and back electronic control translation stage, vertical electronic control translation stage, horizontal electronic control translation stage is connected by card extender between any two with front and back electronic control translation stage, card extender between the horizontal electronic control translation stage of vertical electronic control translation stage is angle block of right angle, light processing unit is fixed on vertical electronic control translation stage.Three-dimensional adjustment System of the present utility model can select the M-404.xPD model translation stage of German PI Corp., and positioning precision is better than 1 μm.
The width of target slit is 1 ~ 2 times (target slit reduce that rear width is pixel dimension by microcobjective 1/10 ~ 1/5) of tested CCD light-sensitive surface pixel width.
The utility model also comprises control acquisition system 12; Control acquisition system comprise light source control unit, direction of motion control module, collecting unit, in order to the computing unit that calculates modulation transfer function and the display unit be connected with tested CCD.
Light source control unit is connected with light source, in order to control light source output brightness; Direction of motion control module is connected with front and back electronic control translation stage with vertical electronic control translation stage, horizontal electronic control translation stage respectively, for controlling the motion of vertical electronic control translation stage in the vertical direction, the motion in the horizontal direction of level of control electronic control translation stage, electronic control translation stage motion in the longitudinal direction before and after controlling; Collecting unit is connected with tested CCD, in order to gather the output image of tested CCD.
Light source 1 can be adopted as halogen tungsten lamp light source, and the wavelength band of light is 350 ~ 950nm, and halogen tungsten lamp light source is through homogenize, and uniform illumination target slit, light source power 150W, can be the illuminance that test provides sufficient.
The specific works principle of the CCD modulation transfer function measurement device that the utility model provides is as follows:
Light source illuminates target slit after homogenize, target slit is imaged on tested CCD light-sensitive surface through the microcobjective of light processing unit, use folding axle mirror turnover light path, check whether the imaging of target slit is positioned on tested CCD light-sensitive surface with eyepiece, by the front and back in three-dimensional adjustment System to translation stage motion adjustment, until see CCD target surface pixel clearly, now fix front and back position, the vertical electronic control translation stage of three-dimensional adjustment System or horizontal electronic control translation stage precision is utilized to move, image is gathered by tested CCD, utilize and control the grey scale change trend that acquisition system extracts tested pixel in image, line spread function (LSF) can be obtained, by extracting R in color CCD image, G, the gray-scale value of B pixel, calculate respectively, just R can be obtained, G, the modulation transfer function of B tri-look.So, the modulation transfer function of the colored pixel of colored CCD different spectral coverage is just obtained.
Adopt CCD modulation transfer function measurement device of the present utility model, measure CCD modulation transfer function method, comprise the following steps:
1) tested CCD light-sensitive surface is checked by eyepiece;
If can view, then carry out step 3), otherwise carry out step 2);
2) adjust vertical electronic control translation stage, horizontal electronic control translation stage and/or front and back electronic control translation stage, repeat step 1);
3) the folding axle mirror in light path is removed;
4) by controlling the display unit of acquisition system, tested CCD light-sensitive surface selects tested pixel, using the picture of target slit on tested CCD light-sensitive surface as target image, guarantee that tested CCD is operated in linear response district, target image is adjusted on the tested pixel of selection, obtain the image that target image is corresponding;
5) move vertical electronic control translation stage or horizontal electronic control translation stage, make target image move to another side from tested pixel, in moving process, obtain tested pixel gray-scale value;
6) with step 6) distance of vertically electronic control translation stage or horizontal electronic control translation stage movement is X-axis, with step 6) the tested pixel gray-scale value that obtains is Y-axis, obtains the line spread function of tested pixel;
7) utilize Hamming window to carry out apodization computing to it, and by one-dimensional discrete Fourier transform, delivery normalization obtain the modulation transfer function of tested pixel;
8) electronic control translation stage or the distance between tested CCD and microcobjective before and after adjustment, repeat step 4) to step 7), in step 4) the same tested pixel of middle selection; Preferably step 8 is repeated for obtaining more objective and accurate result) at least 10 times.
9) step 8 is selected) the maximum modulation transfer function that obtains, as the modulation transfer function of tested CCD;
Present stage, color digital camera, cell phone cameras are very general.Except optical lens is on except the impact of image quality, the modulation transfer function of image device self is also the key affecting optical system imaging ability.So the measurement evaluation of image device (such as: CCD, CMOS etc.) is just being become particularly important, the utility model just with color modulation transport function for emphasis, construct a set of color modulation transport function proving installation, it is of many uses, precision is excellent, is worth referenced and uses for reference.
Claims (6)
1. a CCD modulation transfer function measurement device, is characterized in that: comprise three-dimensional adjustment System, light source and light processing unit; Described smooth processing unit is fixed in three-dimensional adjustment System, and light processing unit comprises target slit and microcobjective; Described target slit and microcobjective are successively set on the emitting light path of described light source, and microcobjective comprises two faces, and one of them face is provided with screw thread, if threaded is image space, another face is object space; The emergent light of described light source is incident by image space, by object space outgoing.
2. CCD modulation transfer function measurement device according to claim 1, is characterized in that: described smooth processing unit also comprises folding axle mirror and eyepiece, and folding axle mirror is arranged in the light path between microcobjective and target slit; Eyepiece is arranged on the top of folding axle mirror, makes, when rotating folding axle mirror, can see tested CCD light-sensitive surface by eyepiece.
3. CCD modulation transfer function measurement device according to claim 1 and 2, it is characterized in that: described three-dimensional adjustment System comprises vertical electronic control translation stage, horizontal electronic control translation stage and front and back electronic control translation stage, horizontal electronic control translation stage is fixed on the electronic control translation stage of front and back, vertical electronic control translation stage is fixed on horizontal electronic control translation stage, vertical electronic control translation stage, mutually vertical between two between horizontal electronic control translation stage and front and back electronic control translation stage, described smooth processing unit is fixed on vertical electronic control translation stage.
4. CCD modulation transfer function measurement device according to claim 3, is characterized in that: the width of described target slit is 1 ~ 2 times of tested CCD light-sensitive surface pixel width.
5. CCD modulation transfer function measurement device according to claim 4, is characterized in that: described CCD modulation transfer function measurement device also comprises control acquisition system; Described control acquisition system comprises light source control unit, direction of motion control module and collecting unit; Described light source control unit is connected with light source; Direction of motion control module is connected with front and back electronic control translation stage with vertical electronic control translation stage, horizontal electronic control translation stage respectively; Collecting unit is connected with tested CCD.
6. CCD modulation transfer function measurement device according to claim 5, is characterized in that: described control acquisition system also comprises the display unit be connected with tested CCD.
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| CN201420560568.4U CN204202849U (en) | 2014-09-26 | 2014-09-26 | A kind of CCD modulation transfer function measurement device |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104280214A (en) * | 2014-09-26 | 2015-01-14 | 中国科学院西安光学精密机械研究所 | CCD modulation transfer function measuring device and method |
| CN106768890A (en) * | 2016-12-28 | 2017-05-31 | 中国科学院长春光学精密机械与物理研究所 | For the gray scale cosine distribution optical target analogue means of modulation transfer function detection |
| CN108225739A (en) * | 2017-12-28 | 2018-06-29 | 北京空间机电研究所 | A kind of camera space automatic optimizating system based on bus |
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2014
- 2014-09-26 CN CN201420560568.4U patent/CN204202849U/en not_active Expired - Fee Related
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104280214A (en) * | 2014-09-26 | 2015-01-14 | 中国科学院西安光学精密机械研究所 | CCD modulation transfer function measuring device and method |
| CN106768890A (en) * | 2016-12-28 | 2017-05-31 | 中国科学院长春光学精密机械与物理研究所 | For the gray scale cosine distribution optical target analogue means of modulation transfer function detection |
| CN106768890B (en) * | 2016-12-28 | 2018-10-23 | 中国科学院长春光学精密机械与物理研究所 | Gray scale cosine distribution optical target simulator for modulation transfer function detection |
| CN108225739A (en) * | 2017-12-28 | 2018-06-29 | 北京空间机电研究所 | A kind of camera space automatic optimizating system based on bus |
| CN108225739B (en) * | 2017-12-28 | 2020-09-18 | 北京空间机电研究所 | Bus-based automatic optimization system for space camera |
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Granted publication date: 20150311 Termination date: 20170926 |