CN115079505B - Prism beam splitting multispectral camera matching calibration device and method based on Talbot effect - Google Patents
Prism beam 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 method based on Talbot effect, wherein the device comprises a multispectral camera, a light splitting prism, a plurality of image sensors and a plurality of adjusting mechanisms, wherein laser emitted from an optical fiber is collimated by a collimating mirror, then collimated parallel laser is vertically irradiated onto a transmission grating, and a periodical grating image is generated behind the transmission grating; the grating images with different spectral bands are separated by the beam splitter prism and are respectively received by the corresponding image sensors, and the image sensors can be adjusted in position and rotation angle by the adjusting mechanisms connected in one-to-one correspondence. The method is based on the lens-free grating self-imaging target with compensated chromatic aberration, only the transmission grating fixed on the flange surface of the camera is required to be irradiated by parallel coherent light, so that the precise matching of the photosensitive surfaces of the multiple image sensors and the respective reference image surfaces is realized, the spatial consistency of the photographed images of 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 light-splitting multispectral camera imaging, in particular to a device and a method for calibrating matching of a prism light-splitting multispectral camera based on Talbot effect.
Background
The quality of the multi-spectrum camera rear end image fusion is closely related to the installation precision of a plurality of separated image sensors, and when the light sensitive surfaces and the standard image surfaces of the plurality of sensors in the camera are dislocated and deflected, the spatial consistency of images in different spectrum bands is reduced, and the resolution of the fused images is reduced.
The prism beam splitting multispectral camera adopts a plurality of beam splitting prisms which are bonded together and are plated with dichroic beam splitting films with different wave bands to divide incident broadband light waves into a plurality of channels, each channel is respectively collected by a black-and-white area array image sensor, multispectral simultaneous imaging is realized, 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 extracting the optical information of a detected target, can extract the signal which cannot be detected by the 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 greatest extent so as to acquire multispectral information with high resolution and high quality. To do this, high precision multiple image sensor mounting calibration is necessary. 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 means of the auxiliary lens, and the installation position of the sensor is adjusted according to the difference of the positions and the definition of the 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, chromatic aberration and distortion of the lens can inevitably generate registration deviation; the early calibration may fail when other imaging lenses are replaced. In addition, since the lens itself has a certain depth of field, when the lens and the target are fixed, the method of discriminating the focus positions of the plurality of sensors by the sharpness of the photographed image of the lens is not accurate enough.
Disclosure of Invention
The invention provides a matching calibration method for a prism beam-splitting multispectral camera based on Talbot effect, which can solve the technical problems.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
Based on multispectral camera, multispectral camera front side income light mouth covers and has transmission grating, its characterized in that:
the multispectral camera is internally provided with a beam splitting prism, a plurality of image sensors and a plurality of adjusting mechanisms, 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 with different spectral bands are separated by the beam splitter prism and are respectively received by the corresponding image sensors, and the image sensors can be adjusted in position and rotation angle by the adjusting mechanisms connected in one-to-one correspondence.
Further, the transmission grating is tightly attached to the flange surface of the camera flange ring of the multispectral camera.
Further, 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 stripes of the grating images in different areas of the light sensing surface.
Further, the beam splitting prism is a beam splitting prism with 2 to N light outlets, and N is a natural number greater than 2.
Further, the adjusting mechanism is mechanically or electromagnetically adjusted.
Further, the collimating lens is one of an achromatic collimating lens group and an off-axis reflecting collimating lens.
On the other hand, the invention also discloses a method for matching and calibrating the prism light-splitting multispectral camera based on the Talbot effect, which adopts the device for matching and calibrating the prism light-splitting multispectral camera based on the Talbot effect, and the installation and calibration method comprises the following steps:
Step S1, calibrating a target transmission grating based on Talbot effect; preparing transmission gratings compatible with different spectral bands, wherein the transmission gratings are segmented, sub-gratings with different periods are engraved on each block, and the grating periods of the sub-gratings on the transmission gratings are controlled, and the Talbot image periods are selected, so that the self-imaging image distance of the gratings with different bands is matched with the flange distance of a camera;
s2, registering and adjusting a plurality of image sensors; the grating self-imaging is used 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 acquired by the image sensor; and the accurate matching among the multiple image sensors is realized by combining an adjusting mechanism connected to the image sensor base.
Further, the registration adjustment of the multiple image sensors is specifically:
Firstly, attaching a transmission grating target with a self-imaging distance equal to the flange distance of a multispectral camera to a flange surface of the multispectral camera, adjusting the rotation angle and the center point position of the transmission grating target, ensuring that the center of a grating plate of the transmission grating passes through a camera optical axis, enabling an X axis of the grating plate to be parallel to the X axis of the camera, and fixing the grating target;
after the positioning of the grating target of the transmission grating is completed, the alignment of the Sensor 1 corresponding to the 1 st spectrum band and the reference image plane is regulated;
Establishing a coordinate system on a reference image plane, wherein an origin O s is the center of the image plane, a Z axis is perpendicular to the image plane and points to the transmission grating, and an X axis and a Y axis are respectively perpendicular and parallel to a grating line of the transmission grating; the image sensor is adjusted, and the specific adjustment steps are as follows:
S21, opening a collimation laser lambda 1, vertically irradiating a transmission grating target, and receiving diffracted light by an image Sensor 1 after the diffracted light passes through a beam splitting prism; focusing on only the taber image of the sub-grating G 1 (p, q), (p, q=1, 2,.. N) photographed by the image Sensor 1, calculating the fringe contrast of each of the G 1 sub-gratings, and repeatedly adjusting the rotation angles θ (X1) and θ (Y1) of the image Sensor 1 about the X-axis and Y-axis thereof and the Z-direction offset Z1 of the image Sensor 1 by using the adjustment mechanism on the back of the image Sensor 1, so as to adjust the fringe contrast of each of the sub-gratings to the maximum; after the adjustment is finished, the light sensitive 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, comparing and shooting clear images of sub-gratings G 1 (p, q) in each of the N X N grating partitions with deviations of positions and angles of ideal sub-grating patterns, calculating the deviations of positions and angles of a sensitive surface of the Sensor 1 and a reference image surface according to the deviations, adjusting a mechanical adjusting mechanism on the back of the Sensor 1, adjusting deviation amounts X1 and Y1 in X-axis and Y-axis directions, and adjusting a rotation angle theta (Z1) of the image Sensor 1 around a Z axis, so that the clear images of all the sub-gratings G 1 (p, q) are aligned with the patterns of the grating Talbot effect self-imaging;
Through the above 2 steps, the image Sensor 1 and the reference image plane are aligned; the image sensor Sensori is adjusted in the above 2 steps sequentially for the i=2, 3..n spectral bands, and the n image sensors and the reference image plane can be aligned, i.e., the alignment registration of the multiple image sensors of the multispectral camera is realized.
According to the technical scheme, the matching calibration method of the prism beam-splitting multispectral camera based on the Talbot effect can realize the accurate matching of the photosensitive surfaces of the multiple image sensors and the respective reference image surfaces by means of the lens-free grating self-imaging targets with compensated chromatic aberration, and ensure the spatial consistency of shot images of different spectral bands.
The grating self-imaging target based on the Talbot effect is used, and the influence of distortion and chromatic aberration is avoided. Through the period of designing the blocking grating, one grating target can be matched with sensors in different wave bands, the image contrast of high-precision grating lines is analyzed, and the accurate matching of a plurality of sensors in the installation calibration process can be ensured. Meanwhile, the grating can be calibrated by only being attached to the flange surface of the camera, and the sensor has no mechanical movement and is simple and reliable to operate.
Compared with the traditional multi-image sensor mounting registration method using a lens to shoot a fixed target, the method is based on the Talbot effect, namely the lens-free imaging technology, realizes the image sensor mounting adjustment reference without chromatic aberration by customizing the grating period, and has wide adaptive spectrum band; the technology for preparing the high-precision grating by photoetching is mature, and compared with a low-chromatic-aberration broadband calibration lens which is difficult to design and high in price, the reference target is easy to mass production; according to the invention, only the transmission grating fixed on the flange surface of the camera is irradiated by parallel coherent light, then the installation deviation of each sensor can be judged by adopting image imaging, the calibration process of the reference target is simple and convenient, and the stability is good.
Drawings
FIG. 1 is a schematic diagram of the structure of the present invention;
FIG. 2 is a schematic diagram of an internal adjustment mechanism of the multispectral camera of the present invention;
FIG. 3 is a schematic diagram of an alignment adjustment of an image sensor with a reference image plane;
the marks in the figure: 1. a laser; 2. a multimode optical fiber; 3. a collimator lens; 4. a transmission grating; 5. a multispectral camera; 6. a camera flange ring; 7. a beam-splitting prism; 8. an image sensor; 81. a first image sensor; 82. a second image sensor; 9. an adjusting mechanism; 91. a first adjustment mechanism; 92. a second adjustment mechanism.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments of the present invention.
The taber effect is a self-imaging effect of a diffraction grating, a transmission grating is vertically irradiated by coherent parallel light, and an image with the same size as the grating appears periodically behind the grating. Through designing the grating period, the Talbot image distance is equal to the multispectral camera flange distance, and the precise grating image can be taken as a reference, so that the grating images acquired by each image sensor are sequentially adjusted to be the clearest by means of a translation and rotation six-degree-of-freedom mechanical adjusting mechanism, and the precise registration of the multispectral image sensors is realized.
As shown in fig. 1, in the prism splitting multispectral camera matching calibration method based on taber effect according to the present embodiment, the laser 1 is formed by combining laser beams with wavelengths of central wavelengths λ i (i=1, 2,..n) of multispectral respective bands S i (i=1, 2,..n), and the laser beams are coupled into the multimode optical fiber 2 after being combined to ensure coaxiality. The laser emitted from the optical fiber is collimated by a collimating lens 3, wherein the collimating lens 3 is one of an achromatic collimating lens group and an off-axis reflecting collimating lens; then the collimated parallel laser irradiates vertically to the transmission grating 4, and a periodical grating image is generated behind the transmission grating 4; the transmission grating 4 is tightly 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 the dichroic film 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 comprises a first adjusting mechanism 91 and a second adjusting mechanism 92, the first adjusting mechanism 91 and the second adjusting mechanism 92 respectively correspondingly adjust the first image sensor 81 and the second image sensor 82, the position and the rotation angle of the image sensor 8 can be adjusted according to the contrast of the stripes of the grating images in different areas of the light sensitive 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 beam splitting, and after the two-band beam splitter prism 7 is replaced by the multiband beam splitter prism 7, the multi-image sensor registration method provided by the invention is still applicable; namely, the beam splitting prism 7 is a beam splitting prism with 2 to N light outlets, and N is a natural number larger than 2; in the drawing, parallel light with a plurality of wavelengths is obtained by using the multimode optical fiber 2 and the collimator lens 3, and other techniques known in the art can be adopted to achieve the same purpose.
The embodiment of the invention discloses a registration scheme of a multi-image sensor in the assembly process of a prism light-splitting multi-spectrum camera based on Talbot effect, namely an installation and calibration method specifically comprises the following steps:
Step S1, calibrating a target transmission grating 4 based on Talbot effect; preparing transmission gratings 4 compatible with different spectral bands, wherein the transmission gratings 4 are segmented, sub-gratings with different periods are carved on each block, and the self-imaging image distance of the gratings with different bands is matched with the flange distance of a camera by controlling the grating periods of the sub-gratings on the transmission gratings 4 and selecting Talbot image periods;
S2, registering and adjusting a plurality of image sensors; the grating self-imaging is used 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 acquired by the image sensor 8; by combining the adjusting mechanism 9 connected to the base of the image sensor 8, accurate matching between the multiple image sensors 8 can be realized. The following are respectively specified:
1. Talbot effect-based transmission grating target
The present invention uses the taber effect of the diffraction grating, i.e., the diffraction grating self-imaging phenomenon, to assist in multi-image sensor registration.
The basic principle of the taber effect is that when a beam of single-color plane light is used to perpendicularly irradiate the transmission grating 4 with the period d, the grating line of the transmission grating 4 is perpendicular to the X-axis, the grating line is parallel to the Y-axis, the surface of the transmission grating 4 is perpendicular to the Z-axis, the amplitude of incident light is 1, and the wavelength lambda is lambda, the complex amplitude of diffracted light transmitted through the transmission grating 4 at the space coordinate points (X, Y) is
Wherein, C n is the nth level Fourier series; j is an imaginary unit; d is the grating period;
After the diffracted light propagates along the Z-axis perpendicular to the grating plane of the transmission grating 4 by a distance Z, the complex amplitude becomes
When the grating period satisfies n 2λ2/d2 < <1, the above formula can be approximated as
When (when)If m is an even number,/>The light intensity distribution I E 2(x,y)|2＝|E1(x,y)|2 is formed into a grating positive image, and the object image is equal in size; if m is odd number,/>The light intensity distribution |E 2(x,y)|2＝-|E1(x,y)|2, i.e. the raster negative image here, is equal in size. Scale/>Is the taber distance.
The center wavelength lambda i (i=1, 2, n.), their taber distances are respectivelyBy designing the grating period D i for each wavelength, and selecting the number of self-imaging periods m i, it is possible to achieve that the position of the grating self-imaging and the distance of the grating are exactly equal to the flange distance D F of the multispectral camera, i.e. D F＝miTi. The self-imaging positions of different wavelengths over a period are thus fully coincident, providing an achromatic target for sensor registration, the imaging positions being referred to as reference image planes.
Since taber imaging is a periodic imaging, thus, for wavelength lambda i (i=1, 2,..n), if the self-imaging is coincident with each other for the grating period d i and the self-imaging period number m i, when the number of self-imaging cycles is an integer multiple of m i, the self-imaging of each wavelength still coincides with each other, i.e. there are multiple achromatic reference image planes, and the distance between two adjacent reference image planes isWhen the grating is designed, a proper grating period d i and a self-imaging period m i are selected, so that the distance between adjacent reference image planes is larger, and the preliminary alignment of the photosensitive surface of the image sensor and a certain reference image plane is ensured through machining precision, and then the nearest reference image plane 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 entire grating plate of the transmission grating 4 is equally divided into NxN blocks (n=3 in the schematic diagram), to accommodate a plurality of wavelengths lambda i, each of which continues to be subdivided into sub-gratings G i (p, q), (p, q=1, 2,..n.), p and q represent specific positions of the sub-gratings in the entire NxN grating plate.
2. Multi-image sensor registration adjustment
Firstly, a transmission grating 4 target with the 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 center of a grating plate of the transmission grating 4 is ensured to pass through a camera optical axis, 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 spectrum band and the reference image plane is started to be adjusted. As shown in fig. 2, a coordinate system is established on the reference image plane, the origin O s is the center of the image plane, the Z axis points to the transmission grating 4 perpendicular to the image plane, and the x axis and the Y axis are perpendicular and parallel to the grating lines of the transmission grating 4, respectively. In the figure, the photosensitive surface of the image sensor 8 has inclination and Z-direction offset relative to the reference image surface of the distance grating D F, so that the acquired taber images of all the sub-gratings are blurred, the image sensor 8 needs to be adjusted, and the specific adjustment steps are as follows:
(1) The collimated laser lambda 1 is turned on, the transmission grating 4 is perpendicularly irradiated to the grating target, and the diffracted light is received by the image Sensor 1 after passing through the beam splitting prism 7. Focusing on only the taber image of the sub-grating G 1 (p, q), (p, q=1, 2,.. The.n.) captured by the image Sensor 1, the fringe contrast of each of the G 1 sub-gratings is calculated, and the fringe contrast of each of the sub-gratings is adjusted to be maximum by repeatedly adjusting the rotation angles θ (X1) and θ (Y1) of the image Sensor 1 about the X-axis and the Y-axis thereof and the Z-direction offset Z1 of the image Sensor 1 by the adjusting mechanism 9 on the back surface of the image Sensor 1. After the adjustment is finished, the light sensitive 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) Comparing the clear images of the sub-gratings G 1 (p, q) in each of the N X N grating partitions with the deviation of the positions and angles of ideal sub-grating patterns, calculating the deviation of the positions and angles of the sensitive surface of the Sensor 1 and the reference image surface according to the deviation, adjusting the adjusting mechanism 9 on the back of the 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, so that the clear images of all the sub-gratings G 1 (p, q) are aligned with the patterns of the self-imaging grating Talbot effect.
Through the above 2 steps, the image Sensor 1 and the reference image plane are aligned. The image sensor Sensori is adjusted in the above 2 steps sequentially for the i=2, 3..n spectral bands, and the n image sensors and the reference image plane can be aligned, i.e., the alignment registration of the multiple image sensors of the multispectral camera is realized.
In summary, compared with the traditional multi-image sensor mounting registration method using a lens to shoot a fixed target, the method provided by the invention is based on the Talbot effect, namely the lens-free imaging technology, realizes the adjustment reference of the image sensor without chromatic aberration by customizing the grating period, and has wide adaptive spectrum band;
the technology for preparing the high-precision grating by photoetching is mature, and compared with a low-chromatic-aberration broadband calibration lens which is difficult to design and high in price, the reference target is easy to mass production;
According to the invention, only the transmission grating fixed on the flange surface of the camera is irradiated by parallel coherent light, then the installation deviation of each sensor can be judged by adopting image imaging, the calibration process of the reference target is simple and convenient, and the stability is good.
In yet another aspect, the 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 invention also discloses a computer device comprising a memory and a processor, the memory storing a computer program which, when executed by the processor, causes the processor to perform the steps of any of the methods described above.
In a further embodiment of the present application, there is also provided a computer program product containing instructions which, when run on a computer, cause the computer to perform the steps of any of the methods of the above embodiments.
It may be 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 explanation, examples and beneficial effects of the related content may refer to corresponding parts in the above method.
Those skilled in the art will appreciate that all or part of the processes in the methods of the above embodiments may be implemented by a computer program for instructing relevant hardware, where the program may be stored in a non-volatile computer readable storage medium, and where the program, when executed, may include processes in the embodiments of the methods described above. Any reference to memory, storage, database, or other medium used in embodiments provided herein may include non-volatile and/or volatile memory. The nonvolatile 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 (SYNCHLINK) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), among others.
The technical features of the above embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.
The above embodiments are only for illustrating the technical solution of the present invention, and are not limiting; although the 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 scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims (9)
1. The utility model provides a prism beam split multispectral camera matches calibrating device based on taber effect, based on multispectral camera, multispectral camera front side light inlet covers has transmission grating, its characterized in that:
the multispectral camera is internally provided with a beam splitting prism, a plurality of image sensors and a plurality of adjusting mechanisms, 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; grating images of different spectrum bands are separated by the beam splitter prism and are respectively received by the corresponding image sensors, and the image sensors can be adjusted in position and rotation angle by adjusting mechanisms which are connected in one-to-one correspondence;
The transmission gratings are segmented, sub-gratings with different periods are engraved on each block, and the grating periods of the sub-gratings on the transmission gratings are controlled, and Talbot image periods are selected, so that the self-imaging image distance of the gratings with different wave bands is matched with the flange distance of the camera.
2. The device for calibrating the matching of the prism-spectroscopic multispectral camera based on the taber effect according to claim 1, wherein the transmission grating is closely attached to the flange surface of the camera flange ring of the multispectral camera.
3. The taber-effect-based prism spectroscopic multispectral camera matching calibration device of claim 1, wherein the dichroic beam splitting prism is coated with a dichroic beam splitting film.
4. The device for calibrating the matching of the prism spectroscopic multispectral camera based on the taber effect according to claim 1, wherein the adjusting mechanism connected to the image sensor adjusts the position and the rotation angle of the image sensor according to the contrast of the stripes of the grating images in different areas of the light sensing surface.
5. The taber-effect-based prism-splitting multispectral camera matching calibration device of claim 1, wherein the splitting prism is a splitting prism having 2-N light outlets, N being a natural number greater than 2.
6. The taber-effect-based prism spectroscopic multispectral camera matching calibration apparatus of claim 1, wherein the adjustment mechanism is a mechanical adjustment or an electromagnetic adjustment.
7. The taber-effect-based prism-spectroscopic multispectral camera matching calibration apparatus of claim 1, wherein the collimating lens is one of an achromatic collimating lens group and an off-axis reflecting collimating lens.
8. The method for matching and calibrating the prism beam-splitting multispectral camera based on the Talbot effect is characterized by comprising the following steps of:
Step S1, calibrating a target transmission grating based on Talbot effect; preparing transmission gratings compatible with different spectral bands, wherein the transmission gratings are segmented, sub-gratings with different periods are engraved on each block, and the grating periods of the sub-gratings on the transmission gratings are controlled, and the Talbot image periods are selected, so that the self-imaging image distance of the gratings with different bands is matched with the flange distance of a camera;
s2, registering and adjusting a plurality of image sensors; the grating self-imaging is used 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 acquired by the image sensor; and the accurate matching among the multiple image sensors is realized by combining an adjusting mechanism connected to the image sensor base.
9. The method for calibrating matching of the prism splitting multispectral camera based on the taber effect according to claim 8, which is characterized in that: the registration adjustment of the multiple image sensors is specifically as follows:
Firstly, attaching a transmission grating target with a self-imaging distance equal to the flange distance of a multispectral camera to a flange surface of the multispectral camera, adjusting the rotation angle and the center point position of the transmission grating target, ensuring that the center of a grating plate of the transmission grating passes through a camera optical axis, enabling an X axis of the grating plate to be parallel to the X axis of the camera, and fixing the grating target;
after the positioning of the grating target of the transmission grating is completed, the alignment of the Sensor 1 corresponding to the 1 st spectrum band and the reference image plane is regulated;
Establishing a coordinate system on a reference image plane, wherein an origin O s is the center of the image plane, a Z axis is perpendicular to the image plane and points to the transmission grating, and an X axis and a Y axis are respectively perpendicular and parallel to a grating line of the transmission grating; the image sensor is adjusted, and the specific adjustment steps are as follows:
S21, opening a collimation laser lambda 1, vertically irradiating a transmission grating target, and receiving diffracted light by an image Sensor 1 after the diffracted light passes through a beam splitting prism; focusing on only the taber image of the sub-grating G 1 (p, q), (p, q=1, 2,.. N) captured by the image Sensor 1, calculating the fringe contrast of each sub-grating G 1 (p, q), repeatedly adjusting the rotation angles θ (X1) and θ (Y1) of the image Sensor 1 about its X-axis and Y-axis, and the Z-direction offset Z1 of the image Sensor 1, by using the adjustment mechanism on the back of the image Sensor 1, and adjusting the fringe contrast of each sub-grating to the maximum; after the adjustment is finished, the light sensitive 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, comparing and shooting clear images of sub-gratings G 1 (p, q) in each of the N X N grating partitions with deviations of positions and angles of ideal sub-grating patterns, calculating the deviations of positions and angles of a photosensitive surface of the Sensor1 and a reference image surface according to the deviations, adjusting a mechanical adjusting mechanism on the back of the Sensor1, adjusting deviation amounts X1 and Y1 in X-axis and Y-axis directions, and adjusting a rotation angle theta (Z1) of the image Sensor around a Z axis, so that the clear images of all the sub-gratings G 1 (p, q) are aligned with the patterns of the grating Talbot effect self-imaging;
Through S21, S22, the image Sensor 1 and the reference image plane are aligned; the image sensor Sensori is adjusted in the above 2 steps sequentially for the i=2, 3..n spectral bands, and the n image sensors and the reference image plane can be aligned, i.e., the alignment registration of the multiple image sensors of the multispectral camera is realized.
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