A long-distance multi-spectral high-resolution imaging method and system

Abstract

The present invention discloses a long-distance multi-spectral high-resolution imaging method and system, comprising the following steps: light carrying an object is converged by an objective lens and then stray light is filtered out by an aperture stop, and then the light enters an imaging device through an eyepiece; the light incident on the imaging device passes through a multi-stage filter device of the imaging device step by step and is collected by an image sensor corresponding to each stage through an imaging lens corresponding to each stage to generate corresponding image information, and a plurality of image information is input into a computer to generate a multi-spectral image; the imaging device is translated multiple times to generate a plurality of multi-spectral images; the computer reconstructs the plurality of multi-spectral images through Fourier ptychography to expand the field-of-view aperture and generate a multi-spectral reconstructed image. The present invention can expand the field-of-view aperture of the imaging system, break through the resolution limitation of traditional long-distance imaging technology, and thus realize multi-spectral imaging and high-resolution imaging on a long-distance target of a simple imaging system.

Description

Technical Field

[0001] The present invention belongs to the field of imaging technology, and particularly relates to a long-distance multi-spectral high-resolution imaging method and system. Background Art

[0002] Existing multi-spectral imaging technology is based on multi-band data technology, which combines imaging technology and spectral technology to detect the two-dimensional geometric space and one-dimensional spectral information of a target, and obtains continuous and narrow-band image data with multi-spectral resolution. It has been widely used in fields such as geology, agriculture, and remote sensing. Fourier ptychography is a super-resolution imaging method that has received much attention at home and abroad in recent years. This technology records the intensity information of a target by adopting a special scanning method, and inversely calculates the phase of the target through a ptychographic reconstruction algorithm, thereby realizing the super-resolution reconstruction of the target. However, at present, Fourier ptychography rarely involves the field of long-distance imaging. Traditional ground target remote sensing technology combines imaging technology and spectral technology to obtain target information, and identifies different targets by collecting the obtained fine spectra. However, due to the diffraction effect caused by the lens's limitation on the wavefront, the light wave emitted from a point on the object plane cannot form an image point on the image plane. Even without considering geometric aberration, it is impossible to achieve the ideal situation of point object forming point image, so high-resolution imaging cannot be realized. Therefore, realizing long-distance high-resolution spectral imaging has important application value in fields such as space remote sensing and ground investigation.

[0003] Currently, there is little research on long-distance Fourier ptychography at home and abroad. Holloway et al. built a reflective long-distance Fourier ptychography imaging model. Subsequently, Jagatap proposed a phase retrieval algorithm for sparse Fourier ptychography. Wang et al. in China proposed a long-distance Fourier ptychography imaging system based on sparse sampling.

[0004] However, these technologies are all reconstruction technologies for long-distance targets, and no technical solution capable of realizing multi-spectral imaging of long-distance targets has been found. Existing long-distance imaging technologies mostly fuse imaging technology and spectral technology, and the overall structure of the system is mostly single-aperture, with a small field of view. In addition, the aperture stop will limit the off-axis point light beam, resulting in a smaller aperture angle of the off-axis point light beam than that of the on-axis point, making the image points at the periphery of the field of view unclear and the imaging resolution lower. And under the existing technology, if the image resolution is to be improved, a more complex opto-mechanical system structure, higher manufacturing cost, and larger volume are required. Summary of the Invention

[0005] In order to solve the above problems existing in the prior art, the present invention provides a long-distance multi-spectral high-resolution imaging method and system. The technical problems to be solved by the present invention are realized through the following technical solutions:

[0006] The first aspect of the embodiment of the present invention provides a long-distance multi-spectral high-resolution imaging method, including the following steps:

[0007] Step 100, the light carrying the target object is converged by the objective lens and then the stray light is filtered by the aperture stop. Subsequently, the light enters the imaging device through the eyepiece;

[0008] Step 200, the light incident on the imaging device passes through the multi-stage filter devices of the imaging device step by step and is collected by the corresponding image sensor after passing through the corresponding imaging lens of each stage, and the corresponding image information is generated. The multiple pieces of image information are input into a computer to generate a multi-spectral image;

[0009] Step 300, the imaging device is translated multiple times. After each translation, steps 100 and 200 are repeated to generate multiple multi-spectral images; wherein, the position before each translation and the position after translation have at least 50% overlap;

[0010] Step 400, the computer reconstructs the multiple multi-spectral images through Fourier ptychography to expand the field-of-view aperture and generates a multi-spectral reconstructed image.

[0011] In an embodiment of the present invention, the number of filter devices in each stage is one, and at least three stages of filter devices are provided. One imaging lens and one image sensor are correspondingly provided for each stage of filter device. A final-stage imaging lens and a final-stage image sensor are also provided after the final-stage filter device;

[0012] The specific steps of step 200 are:

[0013] When the light incident on the imaging device passes through one stage of filter device, it is divided into two beams of light. One beam of light is reflected by the filter device and enters the corresponding imaging lens of this stage, and then is collected by the image sensor to generate the corresponding image information. The other beam of light passes through the filter device of this stage and enters the next stage of filter device. The other beam of light passing through the final-stage filter device enters the final-stage imaging lens and is collected by the final-stage image sensor to generate the corresponding image information. The multiple pieces of image information are input into a computer to generate a multi-spectral image.

[0014] In an embodiment of the present invention, the translation trajectory of the imaging device is a square, and the number of translations is at least 3×3 times.

[0015] In an embodiment of the present invention, the specific steps of step 400 include:

[0016] Step 401, preset the object function of the target object as o 0 (x 0 , y 0 ), then the high-resolution spectrum of the object function is wherein, x0 , y 0 represents the position coordinates of the target object, and k x , k y represents the position coordinates of the target object after being transformed into the frequency spectrum domain;

[0017] Step 402, calculate the low-resolution estimated light field of the image sensor at the coordinates (x′ i , y′ i ) according to formula (1)

[0018]

[0019] where x and y represent the spatial domain coordinates of the target object; k xi , k yi represents the coordinates at the i-th translation position in the frequency spectrum domain; P represents the pupil function; represents the function obtained by low-pass filtering the imaging of the target object after Fourier transform; O represents the changing target function during the image reconstruction process;

[0020] Step 403, use the amplitude I of the multispectral image at the position (x′ i , y′ i ) to i replace the amplitude of the estimated light field , and keep the phase information unchanged to obtain the replaced estimated light field as:

[0021]

[0022] Step 404, transform the replaced estimated light field to the frequency domain, update the corresponding sub-region in the high-resolution spectrum, and keep other regions unchanged. The update function is shown in formula (3):

[0023]

[0024] Step 405, for all the multispectral images collected by the imaging device at all translated positions, repeat steps 402 to 404 to complete the iterative process;

[0025] Step 406, repeat steps 402 to 405 n times until the iteration converges, complete the reconstruction process of the high-resolution target spectrum function, perform Fourier transform on it to obtain the high-resolution complex amplitude information of the target object, which is also the multispectral reconstructed image;

[0026] where the iterative process conforms to the convergence discriminant formula (4):

[0027]

[0028] In a second aspect of the embodiments of the present invention, a long-distance multi-spectral high-resolution imaging system is provided for implementing the method described in the first aspect of the embodiments of the present invention, including: an objective lens, an aperture stop, an eyepiece, an imaging device, and a computer; the objective lens, the aperture stop, the eyepiece, and the imaging device are sequentially arranged along the optical path direction;

[0029] The imaging device includes: a multi-stage filter device, an imaging lens corresponding to each stage of the filter device, and an image sensor;

[0030] The image sensor is electrically connected to the computer and is used for collecting the optical signal passing through the imaging lens and generating image information;

[0031] Wherein, the imaging device makes multiple translations, and the position before each translation and the position after translation have at least 50% overlap;

[0032] The computer is used for generating a multi-spectral image from multiple pieces of the image information and reconstructing multiple multi-spectral images through Fourier ptychography to expand the field-of-view aperture, thereby generating a multi-spectral reconstructed image.

[0033] In an embodiment of the present invention, the computer is further configured to execute steps 401-step 406:

[0034] Step 401, preset the object function of the target object as o 0 (x 0 , y 0 ), then the high-resolution spectrum of the object function is Wherein, x 0 , y 0 represent the position coordinates of the target object, k x , k y represent the position coordinates of the target object after being transformed into the spectral domain;

[0035] Step 402, calculate the low-resolution estimated light field i , y′ i ) of the imaging device according to formula (1)

[0036]

[0037] Wherein, x and y represent the spatial coordinates of the target object; k xi , k yi represent the coordinates at the i-th translation position in the spectral domain; P represents the pupil function; represents the function obtained by low-pass filtering the imaging of the target object after Fourier transform; O represents the changing target function in the process of reconstructing the image;

[0038] Step 403: Use the amplitude I of the multispectral image at the position (x′ i , y′ i ) to replace the amplitude of the estimated light field i , and keep the phase information unchanged to obtain the replaced estimated light field as follows:

[0039]

[0040] Step 404: Transform the replaced estimated light field to the frequency domain, update the corresponding sub-region in the target spectrum, and keep other regions unchanged. The update function is shown in formula (3):

[0041]

[0042] Step 405: Repeat the update process. For all the multispectral images collected by the imaging device at all positions, repeatedly execute Steps 402 to 404 to complete the iterative process;

[0043] Step 406: Repeat Steps 402 to 405 for n times until the iteration converges, complete the reconstruction process of the target spectrum function, perform Fourier transform on it, and obtain the high-resolution complex amplitude information of the sample, that is, the multispectral reconstruction image;

[0044] wherein, the iterative process conforms to the convergence discriminant formula (4):

[0045]

[0046] Advantages of the present invention:

[0047] By translating the imaging device, the present invention can collect multiple overlapping multispectral images of the target object. After reconstructing the multiple overlapping low-resolution multispectral images, the field-of-view aperture of the imaging system can be enlarged, the resolution limitation of the traditional long-distance imaging technology can be broken through, thereby improving the resolution of the reconstructed image, realizing multispectral imaging and high-resolution imaging on a long-distance target of a simple imaging system, and enhancing the imaging effect.

[0048] The following will further elaborate on the present invention in conjunction with the drawings and embodiments. Description of the Drawings

[0049] Figure 1 is a schematic structural diagram of a long-distance multispectral high-resolution imaging system provided by an embodiment of the present invention;

[0050] Figure 2 ​It is a schematic diagram of the translation position of one side of the translation trajectory of the imaging device provided by an embodiment of the present invention.

[0051] Explanation of reference numerals:

[0052] 1 - Target object; 2 - Objective lens; 3 - Aperture stop; 4 - Eyepiece; 7 - Imaging device; 9 - First filter device; 10 - Second filter device; 11 - Final filter device; 12 - Final imaging lens; 13 - First imaging lens; 14 - Second imaging lens; 15 - Third imaging lens; 16 - Final image sensor; 17 - First image sensor; 18 - Second image sensor; 19 - Third image sensor; 20 - Computer. Specific embodiments

[0053] The following further describes the present invention in detail with specific embodiments, but the implementation manners of the present invention are not limited thereto.

[0054] Embodiment 1

[0055] As Figure 1 and Figure 2 shown, the first aspect of the embodiment of the present invention provides a long - distance multi - spectral high - resolution imaging method, including the following steps:

[0056] Step 100, natural light irradiates on the target object 1, and the light carrying the target object 1 is converged by the objective lens 2 and then the stray light is filtered by the aperture stop 3, and then the light enters the imaging device 7 through the eyepiece.

[0057] Step 200, the light incident on the imaging device 7 passes through the multi - stage filter devices of the imaging device 7 step by step, and after passing through the corresponding imaging lens of each stage, it is collected by the corresponding image sensor of each stage to generate corresponding image information, and multiple image information is input into the computer 20 to generate a multi - spectral image.

[0058] Among them, the imaging device 7 includes multi - stage filter devices, multiple imaging lenses and multiple image sensors. The number of each stage of filter device is one, and at least three - stage filter devices are provided. One imaging lens and one image sensor are correspondingly provided for each stage of filter device, and a final imaging lens 12 and a final image sensor 16 are further provided after the final filter device 11.

[0059] Therefore, the specific steps of step 200 are:

[0060] When the light of the incident imaging device 7 passes through one of the filter devices, it is divided into two beams of light. One beam of light is reflected by the filter device and enters the corresponding imaging lens at this level, and then is collected by the image sensor to generate corresponding image information. The other beam of light passes through the filter device at this level and enters the next-level filter device. The other beam of light passing through the last-level filter device 11 enters the last-level imaging lens 12 and is collected by the last-level image sensor 16 to generate corresponding image information. Multiple pieces of image information are input into the computer 20 to generate a multi-spectral image. The filter device only allows light of a specific wavelength to be transmitted. The imaging lens is used to image light of different wavelengths on the image sensor, and the image sensor is used to convert the optical image into an electrical signal.

[0061] In this embodiment, taking the three-level filter device as an example, the process of generating image information is further described:

[0062] The number of filter devices is three, namely the first filter device 9, the second filter device 10, and the last-level filter device 11. On the reflection optical path of the first filter device 9, a first imaging lens 13 and a first image sensor 17 are sequentially arranged. On the reflection optical path of the second filter device 10, a second imaging lens 14 and a second image sensor 18 are sequentially arranged. On the reflection optical path of the last-level filter device 11, a third imaging lens 15 and a third image sensor 19 are sequentially arranged. At the rear end of the last-level filter device 11, a last-level imaging lens 12 and a last-level image sensor 16 are also arranged.

[0063] After the light passes through the eyepiece, a part of the light of a certain wavelength passing through the first filter device 9 is reflected into the first imaging lens 13 and imaged on the first image sensor 17; another part of the light of a certain wavelength passing through the first filter device 9 is allowed to be transmitted and transmitted to the second filter device 10. After being transmitted to the second filter device 10, a part of the light of a certain wavelength is reflected into the second imaging lens 14 and imaged on the second image sensor 18; another part of the light of a certain wavelength passing through the second filter device 10 is allowed to be transmitted and transmitted to the last-level filter device 11. After being transmitted to the last-level filter device 11, a part of the light of a certain wavelength is reflected into the third imaging lens 15 and imaged on the third image sensor 19; another part of the light of a certain wavelength passing through the last-level filter device 11 is allowed to be transmitted and transmitted into the last-level imaging lens 12 and imaged on the last-level image sensor 16; the image information collected by each image sensor is integrated and transmitted to the computer 20, and these pieces of image information constitute a low-resolution multi-spectral image.

[0064] In one embodiment, the number of filter devices, imaging lenses, and image sensors provided can be installed according to actual band requirements, and is not limited to the number shown in the figure. In the imaging optical path, the positions of the filter device, imaging lens, and image sensor can be rotated as a whole according to the optical path and the spatial size of the device, and are not limited to the form shown in the figure.

[0065] Step 300: Translate the imaging device 7 multiple times. Repeat Step 100 and Step 200 at each translated position to generate multiple multi-spectral images. Among them, the position before each translation and the position after translation have at least 50% overlap. Herein, the angle and direction of translation can be arbitrary.

[0066] Preferably, the imaging device 7 is translated multiple times along a square trajectory. Repeat Step 100 and Step 200 at each translated position to generate multiple multi-spectral images. Among them, the position before each translation and the position after translation have at least 50% overlap. The number of translations is at least 3×3 times, and the movement trajectory of the imaging device 7 can form a square, that is, the imaging device 7 has the same number of translations on each side of the trajectory and moves at least three times.

[0067] Taking the square as an example of the translation trajectory, translate the imaging device 7 multiple times (such as 5×5 times, etc., the square translation process is as Figure 2 shown). The translation should ensure that the overlap rate between the imaging device 7 before translation and the imaging device 7 after translation is above 50%, and translate along the square area based on this standard. Each translation can generate a low-resolution multi-spectral image. After the translation is completed, a total of 5×5 low-resolution multi-spectral images are collected. Transmit the image information collected on the image sensor to the computer 20 and reconstruct the multiple low-resolution multi-spectral images into a high-resolution spectral reconstruction image through reconstruction.

[0068] In one embodiment, multiple imaging devices 7 can be provided. At this time, it has the same effect as adding multiple filter devices, imaging lenses, and image sensors. Just perform the above translation process simultaneously for the multiple imaging devices 7, rather than being limited to scanning the entire imaging device 7, and multiple low-resolution multi-spectral images can be collected.

[0069] Step 400: The computer 20 reconstructs the multiple multi-spectral images through Fourier ptychography to expand the field-of-view aperture and generate a multi-spectral reconstruction image. In this embodiment, based on the Fourier ptychography imaging principle, the multiple collected low-resolution multi-spectral images are reconstructed, which can break through the spatial resolution limit. After the entire imaging device 7 is translated multiple times, images of the target object 1 corresponding to different frequency components of the spectrum of the target object 1 can be obtained, and the high-frequency information originally outside the cut-off frequency of the optical system can also be recorded in the form of low-resolution images through frequency shift by the imaging system.

[0070] The specific steps of Step 400 include:

[0071] Step 401: Preset the object function of the target object 1 as o 0 (x 0 , y 0) Then, the high-resolution spectrum of the object function is where x 0 , y 0 represent the position coordinates of the target object 1, k x , k y represent the position coordinates of the target object 1 after being transformed into the frequency domain.

[0072] Step 402: Calculate the low-resolution estimated light field.

[0073] Calculate the low-resolution estimated light field of the image sensor at the coordinates (x′ i , y′ i ) according to formula (1)

[0074]

[0075] where x, y represent the spatial coordinates of the target object 1; k xi , k yi represent the coordinates at the i-th translation position in the frequency domain; P represents the pupil function; represents the function obtained by low-pass filtering the Fourier transform of the imaging of the target object 1; O represents the changing target function in the process of reconstructing the image.

[0076] The imaging process of the target object 1 is divided into two steps. First, it is low-pass filtered by the optical system (the components before the image sensor constitute the optical system) after Fourier transform, and then the intensity information is received by the image sensor after another Fourier transform. Thus, the corresponding low-resolution estimated light field of the image sensor at the coordinates (x′ i , y′ i ) can be calculated

[0077] Step 403: Replace the amplitude of the estimated light field.

[0078] Use the amplitude I i of the low-resolution multispectral image at the position (x′ i , y′ i to replace the amplitude of the estimated light field while keeping the phase information unchanged, and obtain the replaced estimated light field as:

[0079]

[0080] where e represents the function without the replaced amplitude, and u represents the function with the replaced amplitude.

[0081] Step 404: Update the high-resolution spectrum of the high-resolution target object 1 function.

[0082] The estimated light field after replacement Transform it to the frequency domain, update the corresponding sub-region in the high-resolution spectrum, and keep other regions unchanged. The update function is shown in Equation (3) below:

[0083]

[0084] Step 405: Repeat the update process.

[0085] For all the multi-spectral images acquired by the imaging device 7 at all positions, repeat Steps 402 to 404 to complete the iterative process.

[0086] Step 406: Iterate until convergence.

[0087] Repeat Steps 402 to 405 for n times until the iteration converges, complete the reconstruction process of the high-resolution target spectrum function, perform Fourier transform on it, and obtain the high-resolution complex amplitude information of the target object 1, which is also the multi-spectral reconstruction image;

[0088] Among them, the iterative process conforms to the convergence discriminant formula (4):

[0089]

[0090] Through the above steps, the high-resolution multi-spectral reconstruction image can be reconstructed from the multi-spectral images with low resolution saved in the computer 20, breaking through the resolution limit of the traditional long-distance imaging technology based on the long-distance Fourier ptychography technology, and realizing the high-resolution multi-spectral image reconstruction of the long-distance target in cooperation with the spectral technology.

[0091] It should be noted that it is assumed that the detection distance L of the system from the target object 1 is 100 km, the focal length f of the imaging lens is 800 mm, the aperture d is 100 mm, the wavelength λ of the light filtered by the filter device is 650 nm, and it is assumed that the imaging device 7 is translated 5×5 times, and the overlapping rate of the positions before and after each translation is 50%. The translation process is as Figure 2 shown. Then, the original resolution σ1 of the camera (image sensor) lens can be calculated by Equation (5) as:

[0092]

[0093] The synthetic aperture D (field-of-view aperture) of the imaging device 7 after translation is:

[0094] D = d·(1 + n·(1 - p)) = 350 mm (6)

[0095] Among them, n is the number of translations on one side of the square, which is 5, and p is the overlapping rate of 50%.

[0096] Then, the resolution σ2 of the imaging device 7 after translation is:

[0097]

[0098] Then the resolution is improved

[0099] Therefore, by translating the imaging device 7, multiple overlapping multispectral images of the target object 1 can be acquired. After reconstructing the multiple low-resolution multispectral images with an overlapping rate, the field-of-view aperture of the imaging system can be expanded, breaking through the resolution limitation of traditional long-distance imaging technology. As a result, the resolution of the reconstructed image is improved, realizing multispectral imaging and high-resolution imaging of a long-distance target with a simple imaging system, and enhancing the imaging effect.

[0100] Embodiment 2

[0101] As Figure 1 and Figure 2 shown, the second aspect of the embodiments of the present invention provides a long-distance multispectral high-resolution imaging system for implementing the method in Embodiment 1. The system includes: an objective lens 2, an aperture stop 3, an eyepiece, an imaging device 7, and a computer 20; the objective lens 2, the aperture stop 3, the eyepiece, and the imaging device 7 are sequentially arranged along the optical path direction.

[0102] The imaging device 7 includes: a multi-stage filter device, an imaging lens corresponding to each stage of the filter device, and an image sensor. The image sensor is electrically connected to the computer 20, and the image sensor is used to collect the optical signal passing through the imaging lens and generate image information.

[0103] Among them, natural light irradiates on the target object 1, and the light carrying the target object 1 is converged by the objective lens 2 and then the stray light is filtered by the aperture stop 3. Subsequently, the light enters the imaging device 7 through the eyepiece. When the light incident on the imaging device 7 passes through one stage of the filter device, it is divided into two beams of light. One beam of light is reflected by the filter device and enters the corresponding imaging lens of this stage, and then is collected by the image sensor to generate corresponding image information. The other beam of light passes through this stage of the filter device and enters the next stage of the filter device. The other beam of light passing through the last-stage filter device 11 enters the last-stage imaging lens 12 and is collected by the last-stage image sensor 16 to generate corresponding image information. Multiple pieces of image information are input into the computer 20 to generate a multispectral image. The filter device only allows light of a specific wavelength to be transmitted. The imaging lens is used to image light of different wavelengths on the image sensor, and the image sensor is used to convert the optical image into an electrical signal.

[0104] In this embodiment, taking the three-stage filter device as an example, the process of generating image information is further described:

[0105] The number of filter devices is three, namely the first filter device 9, the second filter device 10, and the final-stage filter device 11. On the reflection optical path of the first filter device 9, a first imaging lens 13 and a first image sensor 17 are sequentially arranged. On the reflection optical path of the second filter device 10, a second imaging lens 14 and a second image sensor 18 are sequentially arranged. On the reflection optical path of the final-stage filter device 11, a third imaging lens 15 and a third image sensor 19 are sequentially arranged. At the rear end of the final-stage filter device 11, a final-stage imaging lens 12 and a final-stage image sensor 16 are also arranged.

[0106] After the light passes through the eyepiece, for a part of the wavelengths of the light passing through the first filter device 9, it is reflected into the first imaging lens 13 and forms an image on the first image sensor 17; for another part of the wavelengths of the light passing through the first filter device 9, it is allowed to transmit through and is transmitted to the second filter device 10. After being transmitted to the second filter device 10, a part of the wavelengths of the light is reflected into the second imaging lens 14 and forms an image on the second image sensor 18; for another part of the wavelengths of the light passing through the second filter device 10, it is allowed to transmit through and is transmitted to the final-stage filter device 11. After being transmitted to the final-stage filter device 11, a part of the wavelengths of the light is reflected into the third imaging lens 15 and forms an image on the third image sensor 19; for another part of the wavelengths of the light passing through the final-stage filter device 11, it is allowed to transmit through and is transmitted to the final-stage imaging lens 12 and forms an image on the final-stage image sensor 16; the image information collected by each image sensor is integrated and transmitted to the computer 20, and these image information constitute a low-resolution multi-spectral image.

[0107] Among them, the imaging device 7 performs multiple translations along a square trajectory, and the position before each translation and the position after translation have at least 50% overlap; the number of translations is at least 3×3 times. The moving trajectory of the imaging device 7 can form a square, that is, the imaging device 7 has the same number of translations on each side of the trajectory and moves at least three times. After each translation of the imaging device 7, the computer correspondingly generates a multi-spectral image, and multiple translations generate multiple multi-spectral images.

[0108] The computer 20 is used to generate a multi-spectral image from multiple image information and reconstruct multiple multi-spectral images through Fourier ptychography to expand the field-of-view aperture, generating a multi-spectral reconstructed image. The computer 20 is used to execute the corresponding steps in step 200 in the first embodiment and steps 401 - step 406.

[0109] The imaging system of this embodiment can separate lights of multiple bands through the filter device, and through the processing of multiple imaging lenses and image sensors, obtain spectral images of different bands of the same target object 1. After being processed by the computer 20, a high-resolution multi-spectral reconstructed image of the target object 1 can be obtained.

[0110] The imaging system of this embodiment has a simple structure, does not involve complex optical components, has good stability, and the overall optical system structure only needs to collect low-resolution multi-spectral images. The subsequent reconstruction process is completed on the computer 20, with low cost. The imaging lens used to collect images does not require a large-aperture optical lens, reducing the system cost and also reducing the volume and weight. The imaging method of this embodiment can simultaneously achieve multi-spectral imaging and high-resolution imaging of the target area, improving the imaging efficiency and enhancing the imaging effect.

[0111] In the description of the present invention, it should be understood that the orientation or positional relationships indicated by the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present invention.

[0112] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "a plurality" means two or more, unless otherwise specifically defined.

[0113] In the present invention, unless otherwise clearly specified and limited, the terms "mounted", "connected", "coupled", "fixed", etc. should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the internal communication of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0114] In the present invention, unless otherwise clearly specified and defined, the first feature being "on" or "under" the second feature may include direct contact between the first and second features, or may include the first and second features not being in direct contact but being in contact through additional features therebetween. Moreover, the first feature being "above", "over" and "on top of" the second feature includes the first feature being directly above and diagonally above the second feature, or merely indicating that the first feature has a higher horizontal height than the second feature. The first feature being "under", "below" and "beneath" the second feature includes the first feature being directly below and diagonally below the second feature, or merely indicating that the first feature has a lower horizontal height than the second feature.

[0115] In the description of the present specification, the description with reference to terms such as "one embodiment", "some embodiments", "examples", "specific examples", or "some examples", etc. means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In the present specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in the present specification.

[0116] The above content is a further detailed description of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is only limited to these descriptions. For those of ordinary skill in the technical field to which the present invention pertains, without departing from the concept of the present invention, several simple deductions or substitutions can still be made, and all should be regarded as belonging to the protection scope of the present invention.

Claims

1. A long-distance multi-spectral high-resolution imaging method, characterized in that, it includes the following steps: Step 100, the light carrying the target object (1) is converged by the objective lens (2) and then the stray light is filtered by the aperture stop (3). Subsequently, the light passes through the eyepiece and enters the imaging device (7); Step 200, the light incident on the imaging device (7) passes through the multi-stage filter devices of the imaging device (7) step by step and is collected by the corresponding image sensors after passing through the corresponding imaging lenses of each stage, and a corresponding image information is generated. The multiple image information is input into the computer (20) to generate a multi-spectral image; Step 300, the imaging device (7) is translated multiple times. After each translation, steps 100 and 200 are repeated to generate multiple multi-spectral images; wherein, the position before each translation and the position after translation have at least 50% overlap; Step 400, the computer (20) reconstructs the multiple multi-spectral images through Fourier ptychography to expand the field-of-view aperture and generates a multi-spectral reconstructed image; The number of filter devices in each stage is one, and at least three stages of filter devices are provided. One imaging lens and one image sensor are correspondingly provided for each stage of filter device. A final imaging lens (12) and a final image sensor (16) are also provided after the final-stage filter device (11); The specific steps of the said step 200 are: When the light incident on the imaging device (7) passes through one stage of filter device, it is divided into two beams of light. One beam of light is reflected by the filter device and enters the corresponding imaging lens of this stage, and then is collected by the image sensor to generate the corresponding image information. The other beam of light passes through the filter device of this stage and enters the next stage of filter device. The other beam of light passing through the final-stage filter device (11) enters the final imaging lens (12) and is collected by the final image sensor (16) to generate the corresponding image information. The multiple image information is input into the computer (20) to generate a multi-spectral image.

2. A long-distance multi-spectral high-resolution imaging method according to claim 1, characterized in that, the translation trajectory of the imaging device (7) is a square, and the number of translations is at least 3×3 times.

3. A long-distance multi-spectral high-resolution imaging method according to claim 1, characterized in that, the specific steps of the said step 400 include: Step 401, set the object function of the preset target (1) as o 0 (x 0 , y 0 ), then the high-resolution spectrum of the object function is where x 0 , y 0 represent the position coordinates of the target (1), and k x , k y represent the position coordinates of the target (1) after being transformed into the frequency spectrum domain; Step 402, calculate the low-resolution estimated light field of the image sensor at coordinates (x′ i , y′ i ) according to formula (1) where x and y represent the spatial coordinates of the target object (1); k xi , k yi represents the coordinates at the i-th translation position in the spectral domain; P represents the pupil function; represents the function after the image of the target object (1) is low-pass filtered after Fourier transform; O represents the target function that changes during the reconstruction image process; Step 403, using the amplitude I of the multispectral image at the position (x′ i , y′ i ) to replace the amplitude of the estimated light field i , and keeping the phase information unchanged, to obtain the replaced estimated light field as follows: That is: Step 404, transform the replaced estimated light field to the frequency domain, update the corresponding sub-region in the high-resolution spectrum, and keep other regions unchanged. The update function is shown in Equation (3): Step 405, for all the multi-spectral images collected at all the positions after the imaging device (7) is translated, steps 402 - 404 are repeatedly executed to complete the iterative process; Step 406, steps 402 - 405 are repeated n times until the iteration converges, and the reconstruction process of the high-resolution target spectrum function is completed. Its Fourier transform is performed to obtain the high-resolution complex amplitude information of the target object (1), that is, the multi-spectral reconstructed image; wherein, the iterative process conforms to the convergence discriminant formula (4):

4. A long-distance multi-spectral high-resolution imaging system for implementing the method according to any one of claims 1 - 3, characterized in that, it includes: Objective lens (2), aperture stop (3), eyepiece, imaging device (7) and computer (20); the objective lens (2), the aperture stop (3), the eyepiece and the imaging device (7) are arranged in sequence along the optical path direction; The imaging device (7) includes: a multi-stage filter device, an imaging lens corresponding to each stage of the filter device, and an image sensor; The image sensor is electrically connected to the computer (20) and is used for collecting the optical signal passing through the imaging lens and generating image information; Wherein, the imaging device (7) performs multiple translations, and the position before each translation and the position after translation have at least 50% overlap; The computer (20) is used for generating a multi-spectral image from multiple pieces of the image information and reconstructing multiple multi-spectral images through Fourier ptychography to expand the field-of-view aperture, thereby generating a multi-spectral reconstructed image; Wherein, the number of filter devices in each stage is one, and at least three stages of filter devices are provided. An imaging lens and an image sensor are correspondingly arranged for each stage of filter device. A final imaging lens (12) and a final image sensor (16) are further provided after the final stage of filter device (11).

5. A long-distance multi-spectral high-resolution imaging system according to claim 4, characterized in that the computer (20) is further used to execute steps 401 - step 406: Step 401, set the object function of the preset target (1) as o 0 (x 0 , y 0 ), then the high-resolution spectrum of the object function is where x 0 , y 0 represent the position coordinates of the target (1), k x , k y represent the position coordinates of the target (1) after being transformed into the frequency spectrum domain; Step 402, calculate the low-resolution estimated light field of the imaging device (7) at coordinates (x′ i , y′ i ) according to formula (1) where x and y represent the spatial coordinates of the target object (1); k xi , k yi represents the coordinates at the i-th translation position in the spectral domain; P represents the pupil function; represents the function obtained by low-pass filtering the Fourier transform of the imaging of the target object (1); O represents the target function that changes during the reconstruction image process; Step 403, using the amplitude I of the multispectral image at the position (x′ i , y′ i ) to replace the amplitude of the estimated light field i , and keeping the phase information unchanged, to obtain the replaced estimated light field as follows: That is: Step 404, transform the replaced estimated light field to the frequency domain, update the corresponding sub-region in the target spectrum, and keep other regions unchanged. The update function is shown in Equation (3): Step 405, repeat the update process. For all the multi-spectral images collected by the imaging device (7) at all positions, repeat steps 402 - step 404 to complete the iterative process; Step 406, repeat steps 402 - step 405 for n times until the iteration converges, complete the reconstruction process of the target spectral function, perform Fourier transform on it, and obtain the high-resolution complex amplitude information of the sample, that is, the multi-spectral reconstructed image; Wherein, the iterative process conforms to the convergence discriminant formula (4):

Images