CN115079505A - Prism light splitting multispectral camera matching calibration device and method based on Talbot effect - Google Patents
Prism light splitting multispectral camera matching calibration device and method based on Talbot effect Download PDFInfo
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Abstract
The invention relates to a prism light-splitting multispectral camera matching calibration device and a method based on Talbot effect, wherein the device comprises a light-splitting prism, a plurality of image sensors and a plurality of adjusting mechanisms which are arranged in a multispectral camera, laser emitted from an optical fiber is collimated by a collimating mirror, then collimated parallel laser vertically irradiates a transmission grating, and a periodic grating image is generated behind the transmission grating; the grating images of different spectral wave bands are separated by the light splitting prism and received by the corresponding image sensors respectively, and the adjusting mechanisms connected with the image sensors in a one-to-one correspondence mode can adjust the positions and the rotating angles of the image sensors. The method is characterized in that a lens-free grating self-imaging target with chromatic aberration compensated is used, only parallel coherent light is used for irradiating a transmission grating fixed on a camera flange surface, accurate matching of a multi-image sensor photosensitive surface and respective reference image surfaces is realized, the spatial consistency of images shot in different spectral bands is ensured, the calibration process of the reference target is simple and convenient, and the stability is good.
Description
Technical Field
The invention relates to the technical field of prism beam splitting multispectral camera imaging, in particular to a matching calibration device and method for a prism beam splitting multispectral camera based on the Talbot effect.
Background
The quality of the fusion of the images at the rear end of the multispectral camera is closely related to the installation precision of a plurality of separated image sensors, when the photosensitive surfaces of the sensors in the camera and the standard image surface are dislocated and deflected, the spatial consistency of the images in different spectral bands is reduced, and the resolution of the fused images is reduced.
The prism light-splitting multispectral camera adopts a plurality of light-splitting prisms which are bonded together and plated with dichromatic light-splitting films with different wave bands to split incident broadband light waves into a plurality of channels, each channel is respectively collected by a black-and-white area array image sensor to realize multispectral simultaneous imaging, and a band-pass filter with different transmission wave bands can be additionally arranged in front of each black-and-white area array image sensor according to requirements. The multispectral camera increases the dimension of optical information extraction of a detected target, can extract signals which cannot be detected by conventional visible light, and has important application in the fields of food detection, environment monitoring, semiconductor detection and the like.
The multispectral camera needs to ensure the spatial consistency of different spectral images to the maximum extent so as to acquire multispectral information with high resolution and high quality. To do this, high precision multi-image sensor mounting calibration is essential. The existing multi-image sensor registration method generally needs to introduce an auxiliary lens and a target [ CN107024829B ], the multi-image sensor shoots the target with a fixed pattern by the aid of the auxiliary lens, and the installation position of the sensor is adjusted according to the difference of the positions and the definitions of images acquired by different sensors.
In the adjustment technology of shooting a fixed target by adopting a plurality of image sensors and matching with a lens, the self chromatic aberration and distortion of the lens inevitably generate registration deviation; when other imaging lenses are used, the previous calibration may fail. In addition, since the lens itself has a certain depth of field, when the lens and the target are fixed, the method for determining the focusing positions of the sensors according to the definition of the images captured by the lens is not accurate enough.
Disclosure of Invention
The prism beam splitting multispectral camera matching calibration method based on the Talbot effect can solve the technical problems.
In order to achieve the purpose, the invention adopts the following technical scheme:
based on the multispectral camera, a light inlet at the front side of the multispectral camera is covered with a transmission grating, and the multispectral camera is characterized in that:
the multispectral camera is internally provided with a beam splitter prism, a plurality of image sensors and a plurality of adjusting mechanisms, laser emitted from the optical fiber is collimated by a collimating mirror, then collimated parallel laser vertically irradiates the transmission grating, and a periodic grating image is generated behind the transmission grating; the grating images of different spectral wave bands are separated by the light splitting prism and received by the corresponding image sensors respectively, and the adjusting mechanisms connected with the image sensors in a one-to-one correspondence mode can adjust the positions and the rotating angles of the image sensors.
Furthermore, the transmission grating is tightly attached to the flange surface of a camera flange ring of the multispectral camera.
Furthermore, a dichroic beam splitting film is plated on the beam splitting prism.
Furthermore, an adjusting mechanism connected to the image sensor adjusts the position and the rotation angle of the image sensor according to the contrast of the fringes of the grating images in different areas of the photosensitive surface.
Further, the beam splitter prism is a beam splitter prism with 2-N light outlets, and N is a natural number greater than 2.
Further, the adjusting mechanism is mechanically or electromagnetically adjusted.
Further, the collimating mirror is one of an achromatic collimating lens group and an off-axis reflecting collimating mirror.
On the other hand, the invention also discloses a prism splitting multispectral camera matching calibration method based on the Talbot effect, the prism splitting multispectral camera matching calibration device based on the Talbot effect is adopted, and the mounting calibration method comprises the following steps:
step S1, calibrating the target transmission grating based on the Talbot effect; preparing transmission gratings compatible with different spectral bands, wherein the transmission gratings are divided into blocks, each block is engraved with sub-gratings with different periods, and the self-imaging image distance of the gratings with different bands is matched with the camera flange distance by controlling the grating period of the sub-gratings on the transmission gratings and selecting the Talbot image period;
step S2, registration adjustment of the multiple image sensors; the grating self-imaging is taken as an alignment mark, and the installation deviation of the image sensor is indicated by analyzing the contrast and the definition of each sub-grating image collected by the image sensor; and the precise matching among the multiple image sensors is realized by combining the adjusting mechanism connected on the image sensor base.
Further, the registration adjustment of the multiple image sensors specifically comprises:
firstly, a transmission grating target with a self-imaging distance equal to the flange distance of the multispectral camera is attached to the flange surface of the multispectral camera, the rotation angle and the center point position of the transmission grating target are adjusted, the condition that the center of a grating plate of a transmission grating passes through the optical axis of the camera is ensured, the X axis of the grating plate is parallel to the X axis of the camera, and the grating target is fixed;
after positioning of a grating target of the transmission grating is completed, alignment of a Sensor 1 corresponding to the 1 st spectral band and a reference image surface is adjusted;
establishing a coordinate system on a reference image surface, an origin O s The X axis and the Y axis are respectively vertical and parallel to grating lines of the transmission grating; the image sensor is adjusted, and the specific adjusting steps are as follows:
s21, opening the collimated laser lambda 1 The transmission grating target is vertically irradiated, and the diffracted light is received by an image Sensor 1 after passing through a beam splitting prism; focusing only on the sub-grating G captured by the image Sensor 1 1 (p, q), (p, q ═ 1, 2.., N) talbot images, calculating each block G 1 The stripe contrast of each sub-grating is adjusted to be maximum by repeatedly adjusting the rotation angles theta (X1) and theta (Y1) of the image Sensor 1 around the X axis and the Y axis and the Z-direction offset Z1 of the image Sensor 1 by using an adjusting mechanism on the back surface of the image Sensor 1; is adjusted completelyAfter finishing, the photosensitive surface of the Sensor 1 is parallel to the flange surface, and the distance between the two surfaces is equal to the flange distance;
s22 contrast shooting of sub-raster G in each block of raster partition of whole NxN block 1 (p, q) deviation of the clear image and the ideal sub-grating pattern position and angle, and calculating the position and angle deviation of the Sensor 1 light-sensing surface and the reference image surface based on the deviation, adjusting the mechanical adjustment mechanism of the Sensor 1 back surface, adjusting the deviation amounts X1 and Y1 in the X-axis and Y-axis directions, and the rotation angle theta (Z1) of the image Sensor 1 around the Z-axis, so that all the sub-gratings G are made to be in the same direction 1 (p, q) aligning the sharp image with the grating-talbot self-imaged pattern;
after the 2 steps, the image Sensor 1 is aligned with the reference image surface; sequentially aiming at the i-th, 2, 3-th and n-th spectral bands, the image sensors Sensori are adjusted in the 2 steps, so that the n image sensors and the reference image surface can be aligned, and the multi-image sensor alignment and registration of the multi-spectrum camera are realized.
According to the technical scheme, the prism beam-splitting multispectral camera matching calibration method based on the Talbot effect can realize accurate matching of the light sensing surfaces of the multiple image sensors and respective reference image surfaces by means of the lensless grating self-imaging target with chromatic aberration compensated, and ensures the spatial consistency of images shot in different spectral wave bands.
The grating self-imaging target based on the Talbot effect is used, and the influence of distortion and chromatic aberration is avoided. By designing the period of the partitioned grating, one grating target can be matched with the sensors of different wave bands, the image contrast of the high-precision grating lines is analyzed, and the accurate matching of a plurality of sensors during installation and calibration can be guaranteed. Meanwhile, the grating can be used for calibrating the sensor only by being attached to the flange surface of the camera, mechanical motion is avoided, and operation is simple and reliable.
Compared with the traditional method for installing and registering multiple image sensors by shooting fixed targets through lenses, the method is based on the Talbot effect lens-free imaging technology, realizes the image sensor installation and adjustment reference without chromatic aberration through customizing the grating period, and is wide in adaptive spectral band; the technology for preparing the high-precision grating by photoetching is mature, the low-chromatic aberration broadband calibration lens is difficult to design and expensive in contrast, and the reference target is easy to produce in batches; according to the method, the transmission grating fixed on the flange surface of the camera is irradiated by the parallel coherent light, then the installation deviation of each sensor can be judged through image acquisition, and the calibration process of the reference target is simple and convenient and has good stability.
Drawings
FIG. 1 is a schematic structural view of the present invention;
FIG. 2 is a schematic view of the internal adjustment mechanism of the multispectral camera of the present invention;
fig. 3 is a schematic view of alignment adjustment of the image sensor with the reference image plane;
the labels in the figure are: 1. a laser; 2. a multimode optical fiber; 3. a collimating mirror; 4. a transmission grating; 5. a multispectral camera; 6. a camera flange ring; 7. a beam splitter prism; 8. an image sensor; 81. a first image sensor; 82. a second image sensor; 9. an adjustment mechanism; 91. a first adjustment mechanism; 92. a second adjustment mechanism.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention.
The Talbot effect is a diffraction grating self-imaging effect, a transmission type grating is vertically irradiated by coherent parallel light, and large images such as the grating and the like periodically appear behind the grating. By designing the grating period, the Talbot image distance and the flange distance of the multispectral camera are equal, namely, the precise grating image can be used as a reference, and the grating images acquired by the image sensors are sequentially regulated to be clearest by virtue of a translation and rotation six-degree-of-freedom mechanical regulating mechanism, so that the precise registration of the multiple image sensors is realized.
As shown in fig. 1, the prism-based spectroscopy multispectral camera matching calibration method according to the present embodiment is described, in which the laser 1 is configured to perform multispectral calibration on each of the bands S according to the wavelength i A center wavelength λ of (i ═ 1, 2.., n) i The lasers (i, 2,., n) are combined, and after the combination, the lasers are coupled into the multimode optical fiber 2, so that the coaxiality is ensured. The laser emitted from the optical fiber is collimated by a collimating mirror 3, and the collimating mirror 3 is one of an achromatic collimating lens group and an off-axis reflecting collimating mirror; then, collimated parallel laser is vertically irradiated on the transmission grating 4, and a periodic grating image is generated behind the transmission grating 4; the transmission grating 4 is closely attached to the flange surface of a camera flange ring 6 of the multispectral camera 5, and the transmission grating 4 is arranged on a light inlet of the multispectral camera 5 through the camera flange ring 6; the grating images of different spectral bands are separated by the dichroic prism 7 coated with dichroic films and received by the first image sensor 81 and the second image sensor 82, respectively. The adjusting mechanism 9 connected to the image sensor 8 includes a first adjusting mechanism 91 and a second adjusting mechanism 92, the first adjusting mechanism 91 and the second adjusting mechanism 92 respectively adjust the first image sensor 81 and the second image sensor 82 correspondingly, the position and the rotation angle of the image sensor 8 can be adjusted according to the contrast of the grating image of different areas of the photosensitive surface, and the adjusting mechanism 9 is mechanical adjustment or electromagnetic adjustment. Note that the two-band beam splitter prism 7 in the figure is only used for splitting, and after the two-band beam splitter prism 7 is replaced by the multi-band beam splitter prism 7, the multi-image sensor registration method provided by the invention is still applicable; namely, the beam splitter prism 7 is a beam splitter prism with 2 to N light outlets, and N is a natural number greater than 2; in the illustration, parallel light of multiple wavelengths is obtained by the multimode fiber 2 and the collimator lens 3, and other techniques known in the art may be used to achieve the same purpose.
The embodiment of the invention discloses a registration scheme of a multi-image sensor in the process of assembling a prism beam-splitting multi-spectral camera based on a Talbot effect, namely an installation and calibration method specifically comprises the following steps:
step S1, calibrating the target transmission grating 4 based on the Talbot effect; preparing transmission gratings 4 compatible with different spectral wave bands, wherein the transmission gratings 4 are partitioned, each sub-grating is carved with a different period, and the self-imaging image distance of the gratings with different wave bands is matched with the camera flange distance by controlling the grating period of the sub-grating on the transmission grating 4 and selecting a Talbot image period;
step S2, registration adjustment of the multiple image sensors; the grating self-imaging is taken as an alignment mark, and the installation deviation of the image sensor 8 is indicated by analyzing the contrast and the definition of each sub-grating image collected by the image sensor 8; and the precise matching among the multiple image sensors 8 can be realized by combining the adjusting mechanism 9 connected on the base of the image sensor 8. The following are specifically described:
1. transmission grating target based on Talbot effect
The invention uses the Talbot effect of the diffraction grating, namely the self-imaging phenomenon of the diffraction grating, to assist the registration of the multi-image sensor.
The basic principle of the Talbot effect is that when a beam of monochromatic plane light is used for vertically irradiating a transmission grating 4 with a period d, the grating lines of the transmission grating 4 are perpendicular to an X axis, the grating lines are parallel to a Y axis, the surface of the transmission grating 4 is perpendicular to a Z axis, the amplitude of incident light is 1, the wavelength is lambda, and the complex amplitude of diffracted light passing through the transmission grating 4 at a spatial coordinate point (X, Y) is
Wherein, C n Is the nth Fourier series; j is an imaginary unit; d is the grating period;
after the diffracted light propagates a distance Z along the Z-axis perpendicular to the grating surface of the transmission grating 4, the complex amplitude becomes
When the grating period satisfies n 2 λ 2 /d 2 <<1, the above formula can be approximated to
When the temperature is higher than the set temperature
When, ifm is an even number, m is an integer,
light intensity distribution | E 2 (x,y)| 2 ＝|E 1 (x,y)| 2 Namely, the size of the raster positive image and the size of the object image are equal; if m is an odd number, the number of the groups,
light intensity distribution | E 2 (x,y)| 2 ＝-|E 1 (x,y)| 2 I.e. here the grating negative, the object image, etc. is equally large. Balance
Is the Talbot distance.
Center wavelength λ for multiple spectral bands i (i ═ 1, 2.., n), the Talbot distances of which are each
For each wavelength, by designing the grating period d i And selecting the number m of self-imaging cycles i The distance between the grating self-imaging position and the grating is just equal to the flange distance D of the multispectral camera F I.e. D F ＝m i T i . The self-imaging positions of different wavelengths for a period completely coincide, providing an achromatic target for sensor registration, referred to as the reference image plane.
Since Talbot imaging is periodic imaging, for wavelength λ i (i 1, 2.. times.n), if for grating period d i And the number m of self-imaging cycles i When the self-imaging periods are m i At integral multiple of the above, the self-images of the respective wavelengths still coincide with each other, i.e. there are a plurality of achromatic reference image planes, and the distance between two adjacent reference image planes is
In the design of the grating, a suitable grating period d is selected i And the number m of self-imaging cycles i Can make the distance between adjacent reference image planesAnd the image sensor is larger, the photosensitive surface of the image sensor is ensured to be preliminarily aligned with a certain reference image surface through machining precision, and the nearest reference image surface is used as a reference target for adjustment in further adjustment and calibration.
As shown in the front view of the transmission grating 4 in fig. 1, the whole block grating plate of the transmission grating 4 is divided into NxN blocks (N is 3 in the diagram) for compatibility with multiple wavelengths λ i Wherein each block is continuously subdivided into periods d i Sub-grating G of i (p, q), (p, q ═ 1, 2., N), p, q denote the specific position of the sub-gratings in the entire NxN grating plate.
2. Multi-image sensor registration adjustment
Firstly, a transmission grating 4 target with a self-imaging distance equal to the flange distance of the multispectral camera 5 is attached to the flange surface of the multispectral camera 5, the rotation angle and the center point position of the transmission grating 4 grating target are adjusted, the condition that the center of a grating plate of the transmission grating 4 passes through the optical axis of the camera is ensured, the X axis of the grating plate is parallel to the X axis of the camera, and the grating target is fixed.
After the positioning of the grating target of the transmission grating 4 is completed, the alignment of the Sensor 1 corresponding to the 1 st spectral band and the reference image surface is adjusted. As shown in FIG. 2, a coordinate system is established on the reference image plane, the origin O s The Z axis is perpendicular to the image surface and points to the transmission grating 4, and the X axis and the Y axis are respectively perpendicular to and parallel to grating lines of the transmission grating 4. The figure shows the image sensor 8 with its light-sensitive surface facing the range grating D F The reference image surface has inclination and Z-direction offset, which causes that each sub-grating Talbot image collected is blurred, and the image sensor 8 needs to be adjusted, wherein the specific adjustment steps are as follows:
(1) opening collimated laser λ 1 The transmission grating 4 is vertically irradiated on the grating target, and the diffracted light is received by the image Sensor 1 after passing through the beam splitter prism 7. Focusing only on the sub-grating G captured by the image Sensor 1 1 (p, q), (p, q ═ 1, 2.., N) talbot images, calculating each block G 1 The contrast of the stripes of the sub-gratings is adjusted repeatedly by the adjusting mechanism 9 on the back of the image Sensor 1 to the rotation angles theta (X1) and theta (Y1) of the image Sensor 1 around the X axis and the Y axis thereof, and the figureThe Z-offset Z1 of the image Sensor 1 maximizes the fringe contrast for each block of sub-gratings. After the adjustment is finished, the photosensitive surface of the Sensor 1 is parallel to the flange surface, and the distance between the two surfaces is equal to the flange distance.
(2) Contrast shooting of sub-gratings G in each block of the whole NxN block grating partition 1 (p, q) deviation of the clear image and the ideal sub-grating pattern position and angle, and calculating the position and angle deviation of the light-sensing surface of Sensor 1 from the reference image surface based thereon, adjusting the adjusting mechanism 9 on the back surface of Sensor 1, adjusting the deviation amounts X1 and Y1 in the X-axis and Y-axis directions, and the rotation angle theta (Z1) of the image Sensor 1 around the Z-axis, and making all the sub-gratings G 1 The sharp image of (p, q) is aligned with the pattern self-imaged by the grating-talbot effect.
After the above 2 steps, the image Sensor 1 and the reference image surface are aligned. Sequentially aiming at the i-th, 2, 3-th and n-th spectral bands, the image sensors Sensori are adjusted in the 2 steps, so that the n image sensors and the reference image surface can be aligned, and the multi-image sensor alignment and registration of the multi-spectrum camera are realized.
In conclusion, compared with the traditional method for installing and registering a plurality of image sensors by using a lens to shoot a fixed target, the method is based on the Talbot effect lens-free imaging technology, realizes the image sensor installation and adjustment reference without chromatic aberration by customizing the grating period, and has wide adaptive spectral band;
the technology for preparing the high-precision grating by photoetching is mature, the low-chromatic aberration broadband calibration lens is difficult to design and expensive in contrast, and the reference target is easy to produce in batches;
according to the method, the transmission grating fixed on the flange surface of the camera is irradiated by the parallel coherent light, then the installation deviation of each sensor can be judged through image acquisition, and the calibration process of the reference target is simple and convenient and has good stability.
In yet another aspect, the present invention also discloses a computer readable storage medium storing a computer program which, when executed by a processor, causes the processor to perform the steps of any of the methods described above.
In yet another aspect, the present invention also discloses a computer device comprising a memory and a processor, the memory storing a computer program, the computer program, when executed by the processor, causing the processor to perform the steps of any of the methods as described above.
In a further embodiment provided by the present application, there is also provided a computer program product comprising instructions which, when run on a computer, cause the computer to perform the steps of any of the methods of the above embodiments.
It is understood that the system provided by the embodiment of the present invention corresponds to the method provided by the embodiment of the present invention, and the explanation, the example and the beneficial effects of the related contents can refer to the corresponding parts in the method.
It will be understood by those skilled in the art that all or part of the processes of the methods of the embodiments described above can be implemented by a computer program, which can be stored in a non-volatile computer-readable storage medium, and can include the processes of the embodiments of the methods described above when the program is executed. Any reference to memory, storage, database, or other medium used in the embodiments provided herein may include non-volatile and/or volatile memory, among others. Non-volatile memory can include read-only memory (ROM), Programmable ROM (PROM), Electrically Programmable ROM (EPROM), Electrically Erasable Programmable ROM (EEPROM), or flash memory. Volatile memory can include Random Access Memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in a variety of forms such as Static RAM (SRAM), Dynamic RAM (DRAM), Synchronous DRAM (SDRAM), Double Data Rate SDRAM (DDRSDRAM), Enhanced SDRAM (ESDRAM), Synchronous Link DRAM (SLDRAM), Rambus Direct RAM (RDRAM), direct bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).
The technical features of the above embodiments can be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the above embodiments are not described, but should be considered as the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (9)
1. A prism beam-splitting multispectral camera matching calibration device based on Talbot effect is based on a multispectral camera, a light inlet on the front side of the multispectral camera is covered with a transmission grating, and the prism beam-splitting multispectral camera matching calibration device is characterized in that:
the multispectral camera is internally provided with a beam splitter prism, a plurality of image sensors and a plurality of adjusting mechanisms, laser emitted from the optical fiber is collimated by a collimating mirror, then collimated parallel laser vertically irradiates the transmission grating, and a periodic grating image is generated behind the transmission grating; the grating images of different spectral wave bands are separated by the light splitting prism and received by the corresponding image sensors respectively, and the adjusting mechanisms connected with the image sensors in a one-to-one correspondence mode can adjust the positions and the rotating angles of the image sensors.
2. The matching calibration device for prism spectroscopy multispectral camera based on the Talbot effect as claimed in claim 1, wherein the transmission grating is tightly attached to a flange surface of a camera flange ring of the multispectral camera.
3. The taber effect based prism-based spectroscopy multispectral camera matching calibration device of claim 1, wherein the dichroic beam splitter film is coated on the beam splitter prism.
4. The matching calibration device for prism spectroscopy multispectral camera based on the Talbot effect as claimed in claim 1, wherein the adjusting mechanism connected to the image sensor adjusts the position and rotation angle of the image sensor according to the contrast of the fringes of the grating image in different regions of the photosensitive surface.
5. The matching calibration device for prism-based spectroscopy multispectral camera according to claim 1, wherein the beam splitter prism is a beam splitter prism having 2-N light outlets, and N is a natural number greater than 2.
6. The taber-effect-based prism spectroscopy multispectral camera matching calibration device of claim 1, wherein the adjustment mechanism is mechanical adjustment or electromagnetic adjustment.
7. The taber-effect-based prism-splitting multispectral camera matching calibration device as claimed in claim 1, wherein the collimating mirror is one of an achromatic collimating lens set and an off-axis reflecting collimating mirror.
8. A matching calibration method for prism-based spectroscopy multispectral camera based on talbot effect, which adopts the matching calibration device for prism-based spectroscopy multispectral camera based on talbot effect in any one of claims 1-7, characterized in that the mounting calibration method comprises the following steps:
step S1, calibrating the target transmission grating based on the Talbot effect; preparing transmission gratings compatible with different spectral bands, wherein the transmission gratings are divided into blocks, each block is engraved with sub-gratings with different periods, and the self-imaging image distance of the gratings with different bands is matched with the camera flange distance by controlling the grating period of the sub-gratings on the transmission gratings and selecting the Talbot image period;
step S2, registration adjustment of the multiple image sensors; the grating self-imaging is taken as an alignment mark, and the installation deviation of the image sensor is indicated by analyzing the contrast and the definition of each sub-grating image collected by the image sensor; and the precise matching among the multiple image sensors is realized by combining the adjusting mechanism connected on the image sensor base.
9. The matching calibration method for prism-splitting multispectral camera based on Talbot effect as claimed in claim 8, wherein: the registration adjustment of the multiple image sensors comprises the following specific steps:
firstly, a transmission grating target with a self-imaging distance equal to the flange distance of the multispectral camera is attached to the flange surface of the multispectral camera, the rotation angle and the center point position of the transmission grating target are adjusted, the condition that the center of a grating plate of a transmission grating passes through the optical axis of the camera is ensured, the X axis of the grating plate is parallel to the X axis of the camera, and the grating target is fixed;
after positioning of a grating target of the transmission grating is completed, alignment of a Sensor 1 corresponding to the 1 st spectral band and a reference image surface is adjusted;
establishing a coordinate system on a reference image surface, an origin O s The X axis and the Y axis are respectively vertical and parallel to grating lines of the transmission grating; the image sensor is adjusted, and the specific adjusting steps are as follows:
s21, opening the collimated laser lambda 1 The transmission grating target is vertically irradiated, and the diffracted light is received by an image Sensor 1 after passing through a beam splitting prism; focusing only on the sub-grating G captured by the image Sensor 1 1 (p, q), (p, q ═ 1, 2.., N) talbot images, calculating each block G 1 The stripe contrast of each sub-grating is adjusted to be maximum by repeatedly adjusting the rotation angles theta (X1) and theta (Y1) of the image Sensor 1 around the X axis and the Y axis and the Z-direction offset Z1 of the image Sensor 1 by using an adjusting mechanism on the back surface of the image Sensor 1; after the adjustment is finished, the photosensitive surface of the Sensor 1 is parallel to the flange surface, and the distance between the two surfaces is equal to the flange distance;
s22 contrast shooting of sub-raster G in each block of raster partition of whole NxN block 1 (p, q) deviation of the clear image and the ideal sub-grating pattern position and angle, and calculating the position and angle deviation of the Sensor 1 light-sensing surface and the reference image surface based on the deviation, adjusting the mechanical adjustment mechanism of the Sensor 1 back surface, adjusting the deviation amounts X1 and Y1 in the X-axis and Y-axis directions, and the rotation angle theta (Z1) of the image Sensor 1 around the Z-axis, so that all the sub-gratings G are made to be in the same direction 1 Clear image and light of (p, q)Aligning the self-imaged patterns of the grating Talbot effect;
after the 2 steps, the image Sensor 1 is aligned with the reference image surface; sequentially aiming at the i-th, 2, 3-th and spectral wave bands, the image sensors Sensori are adjusted in the 2 steps, so that the n image sensors and the reference image surface can be aligned, and the alignment and registration of the multiple image sensors of the multispectral camera are realized.
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