A pushbroom hyperspectral imaging device based on metasurface structure

Abstract

The present application relates to the technical field of spectral imaging, in particular to a push-broom hyperspectral imaging device based on a super surface structure, comprising an imaging lens, a slit, a super surface spectral imaging system for realizing collimation function, spectral function and focusing function through physical spectral splitting, a sensor and an image control board. The present application is suitable for the wavelength range supporting deep ultraviolet band, ultraviolet band, visible light band, near infrared band, short wave infrared band, medium wave infrared band and far infrared band through the mutual cooperation of the imaging lens, the slit, the super surface spectral imaging system, the sensor and the image control board, has high spectral fineness, can easily achieve nanometer or sub-nanometer spectral resolution, simultaneously adopts the super surface spectral imaging system capable of realizing collimation function, spectral function and focusing function, can realize super high precision spectral splitting, and does not need reconstruction calculation, simultaneously optimizes the optical system, has compact structure, small volume, and can be put into use only after a small amount of debugging.

Description

Technical Field

[0001] This invention relates to the field of spectral imaging technology, and more specifically to a pushbroom hyperspectral imaging device based on metasurface structure. Background Technology

[0002] Hyperspectral imaging technology is being applied in an increasing number of fields, and the principles of imaging technology are constantly being updated. Currently, the traditional grating + lens group solution is the most widely used, but it is bulky, has a complex optical path system, and is difficult to assemble. It is difficult to improve and adapt it to meet the needs of industrial hyperspectral applications. Therefore, existing technologies generally use metasurface multispectral technology. In recent years, metasurface multispectral technology has become more and more mature, but it still has many shortcomings. Its operation requires a reconstruction algorithm. During operation, the reconstruction algorithm is related to the consistency of metasurface structure processing, installation consistency, and field environment. This means that the reconstruction algorithm needs to be adjusted for each device, and the pre-use calibration is very complicated. As a result, the existing metasurface multispectral technology is not adaptable to different environments. Changes in environmental conditions have a large uncertainty in the impact on measurement results. At the same time, the number of bands in the existing metasurface multispectral technology is relatively small, making it difficult to accurately measure the fine spectrum of the object being photographed. Therefore, its application fields are relatively limited and its practicality is poor. Summary of the Invention

[0003] The technical problem to be solved by this invention is that the existing spectral imaging technology has a relatively complex structure and optical path system, resulting in a large size and poor versatility. At the same time, it requires a customized reconstruction algorithm during operation, and the pre-use calibration is very complicated. In addition, the imaging accuracy is poor and the number of multispectral bands is small.

[0004] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: a pushbroom hyperspectral imaging device based on metasurface structure, comprising:

[0005] An image-capturing lens is used to collect light from the target area and focus it onto the slit;

[0006] A slit, used to limit the width of incoming light;

[0007] Metasurface beam-splitting imaging system is used to achieve collimation, beam splitting and focusing functions through physical beam splitting.

[0008] A sensor used to sense incident light within the corresponding wavelength range and output digital or analog signals;

[0009] The image control board is used to coordinate the entire imaging process, as well as to acquire, process, and transmit image signals from the sensor.

[0010] The imaging lens, the slit, the metasurface beam splitting imaging system, and the sensor's imaging area are connected along the direction of the optical path. The sensor is connected to the image control board, which is connected to the corresponding external device via a transmission interface. After capturing an image of the target area, the imaging lens acquires the light signal of the entire target area to focus the light onto the slit. The linear portion of the light passing through the slit is given to the metasurface beam splitting imaging system. The metasurface beam splitting imaging system collimates, splits, and focuses the linear portion of the light to acquire and focus the light of the corresponding wavelength onto the sensor's imaging area.

[0011] When this invention is in operation, through the cooperation of the imaging lens, slit, metasurface beam-splitting imaging system, sensor, and image control board, it is applicable to the deep ultraviolet, ultraviolet, visible, near-infrared, short-wave infrared, mid-wave infrared, and far-infrared wavelength ranges, and can support some or all of the above bands or mixed bands. It has high spectral precision, easily achieving nanometer or sub-nanometer spectral resolution. At the same time, it adopts a metasurface beam-splitting imaging system that can realize collimation, beam splitting, and focusing functions, enabling ultra-high precision beam splitting without the need for reconstruction calculations. It also optimizes the optical path system, resulting in a compact structure, small size, and reduced number of parts, making it easy to deploy and requiring only a small amount of debugging before it can be put into use.

[0012] Preferably, the metasurface spectroscopic imaging system includes at least one metasurface component, which includes several medium pillars with different refractive indices and a background medium, with the medium pillars arranged in the background medium.

[0013] Preferably, the array layout between several dielectric pillars is set as a one-dimensional linear array.

[0014] Preferably, the cross-sectional shape of the medium column is at least one of a circle, a square, and a triangle.

[0015] Preferably, the arrangement of the dielectric pillars is set to a periodic arrangement, and the periodic arrangement of the dielectric pillars is determined according to the period of the narrowband spectral wavelength range to be achieved. The size of the dielectric pillars is set to be smaller than the target wavelength, and the center distance between the dielectric pillars and the adjacent dielectric pillars is set to the sum of the ratio of the target wavelength to the effective refractive index of the dielectric pillar and a preset correction parameter.

[0016] Preferably, the arrangement of the dielectric pillars is set to random or quasi-periodic arrangement, and the dimensions of the dielectric pillars are set to several different characteristic dimensions determined according to the required broadband spectral wavelength range.

[0017] Preferably, the positions and sizes of several medium columns are arranged in the background medium in a completely random manner.

[0018] Preferably, the positions and sizes of several medium columns are arranged in the background medium in a quasi-periodic manner.

[0019] In operation, this invention employs dielectric pillars with different refractive indices and a background medium. By combining different cross-sectional shapes of the dielectric pillars and varying the spacing between them, the desired wavelength range for beam splitting is covered. When periodically arranged dielectric pillars are used, a metasurface with a specific frequency response can be created, thereby efficiently separating light within the desired wavelength range. When randomly or quasi-periodicly arranged dielectric pillars are used, efficient beam splitting over a wider frequency band can be achieved, and a uniform optical response can be provided over a wide frequency band. Furthermore, using quasi-periodicly arranged dielectric pillars can further improve the beam splitting performance over a wide frequency band. This invention has a wide range of applications and good versatility. Moreover, by setting the array layout between several dielectric pillars as a one-dimensional linear array, it is suitable for pushbroom imaging, resulting in high imaging accuracy and good imaging effect.

[0020] Preferably, the slit is positioned at the focal point of the imaging lens, and the imaging portion of the sensor is positioned at the focal point of the metasurface beamforming system.

[0021] Preferably, the system also includes a structural component, on which the imaging lens, slit, metasurface beamforming system, and sensor are all fixedly mounted.

[0022] The beneficial technical effects of this invention include:

[0023] 1. This invention, through the coordinated operation of an imaging lens, a slit, a metasurface beam-splitting imaging system, a sensor, and an image control board, is applicable to wavelength ranges including deep ultraviolet, ultraviolet, visible light, near-infrared, short-wave infrared, mid-wave infrared, and far-infrared bands. It can also support some or all of the above bands or mixed bands. It has high spectral precision, easily achieving nanometer or sub-nanometer spectral resolution. At the same time, it adopts a metasurface beam-splitting imaging system that can realize collimation, beam splitting, and focusing functions, enabling ultra-high precision beam splitting without the need for reconstruction calculations. Furthermore, the optical path system is optimized, resulting in a compact structure, small size, and reduced number of parts, facilitating deployment and requiring only minimal debugging before use.

[0024] 2. This invention employs dielectric pillars and background media with different refractive indices. By combining different cross-sectional shapes of the dielectric pillars and varying the spacing between them, the desired wavelength range for beam splitting can be covered. When periodically arranged dielectric pillars are used, a metasurface with a specific frequency response can be created, thereby efficiently separating light within the desired wavelength range. When randomly or quasi-periodicly arranged dielectric pillars are used, efficient beam splitting over a wider frequency band can be achieved, and a uniform optical response can be provided over a wide frequency band. Furthermore, using quasi-periodicly arranged dielectric pillars can further improve the beam splitting performance over a wide frequency band. It has a wide range of applications and good versatility. Moreover, by setting the array layout between several dielectric pillars as a one-dimensional linear array, it is suitable for pushbroom imaging, resulting in high imaging accuracy and good imaging effect.

[0025] Other features and advantages of the present invention will be disclosed in detail in the following detailed description and accompanying drawings. Attached Figure Description

[0026] The invention will be further described below with reference to the accompanying drawings:

[0027] Appendix Figure 1 This is an exploded view of a pushbroom hyperspectral imaging device based on a metasurface structure. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be explained and described below with reference to the accompanying drawings. However, the following embodiments are only preferred embodiments of the present invention and not all of them. Other embodiments obtained by those skilled in the art based on the embodiments in the implementation methods without creative effort are all within the protection scope of the present invention.

[0029] In the following description, terms such as “inner,” “outer,” “upper,” “lower,” “left,” and “right” are used only to indicate orientation or positional relationship for the convenience of describing the embodiments and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0030] Example 1:

[0031] Please see the appendix Figure 1This embodiment discloses a pushbroom hyperspectral imaging device based on a metasurface structure, including an imaging lens 1 for collecting light from a target area and focusing it onto a slit 2; the slit 2 for limiting the width of the incoming light; a metasurface beam-splitting imaging system 3 for achieving collimation, beam splitting, and focusing functions through physical beam splitting; a sensor 4 for sensing incident light within the responsive wavelength range and outputting digital-analog signals; and an image control board 5 for coordinating the entire imaging process and acquiring, processing, and transmitting image signals from the sensor 4. A detailed description is provided below with reference to the accompanying drawings.

[0032] Please see the appendix Figure 1 In this embodiment, the imaging part of the imaging lens 1, the slit 2, the metasurface beam splitting imaging system 3, and the imaging part of the sensor 4 are connected along the direction of the light path extension. The sensor 4 is connected to the image control board 5. The image control board 5 is connected to the corresponding external device through the transmission interface. After the imaging lens 1 captures the image of the target area, it acquires the light signal of the entire target area to focus the light on the slit 2. The linear light portion of the light transmitted through the slit 2 is given to the metasurface beam splitting imaging system 3. The metasurface beam splitting imaging system 3 collimates, splits, and focuses the linear light portion and then acquires and focuses the light of the corresponding wavelength band onto the imaging part of the sensor 4.

[0033] In this embodiment, through the cooperation of the imaging lens 1, slit 2, metasurface beam-splitting imaging system 3, sensor 4, and image control board 5, the applicable wavelength range supports deep ultraviolet, ultraviolet, visible light, near-infrared, short-wave infrared, mid-wave infrared, and far-infrared bands. It can also support some or all of the above bands or mixed bands. The spectral precision is high, easily achieving nanometer or sub-nanometer spectral resolution. At the same time, the metasurface beam-splitting imaging system 3, which can realize collimation, beam splitting, and focusing functions, can achieve ultra-high precision beam splitting without the need for reconstruction calculations. The optical path system is also optimized, resulting in a compact structure, small size, and reduced number of parts, making it easy to deploy and requiring only a small amount of debugging before it can be put into use.

[0034] Preferably, the slit 2 is positioned at the focal point of the imaging lens 1, and the imaging part of the sensor 4 is positioned at the focal point of the metasurface beam-splitting imaging system 3. In order to further improve structural stability and facilitate processing and deployment, a structural component is also included. The imaging lens 1, slit 2, metasurface beam-splitting imaging system 3 and sensor 4 are all fixedly mounted on the structural component.

[0035] In practical implementation, the metasurface spectral imaging system 3 includes at least one metasurface component 31. The metasurface component 31 includes several dielectric pillars with different refractive indices and a background medium. The dielectric pillars are arranged in the background medium. During operation, one or more metasurface components 31 can be set. When only one metasurface component 31 is set, the collimation function, spectral splitting function and focusing function are simultaneously realized by one metasurface component 31. This can greatly simplify the optical path system and facilitate the arrangement of the metasurface spectral imaging system, simplifying the arrangement steps. At the same time, setting the array layout between several dielectric pillars as a one-dimensional linear array can realize pushbroom spectral imaging, achieve efficient spectral splitting and high spectral resolution acquisition, high imaging accuracy and good imaging effect.

[0036] In specific implementation, sensor 4 can preferably be a linear CCD or CMOS detector, which is suitable for processing data acquired line by line during pushbroom imaging. Of course, any other suitable sensing device can also be used.

[0037] Example 2:

[0038] Please see the appendix Figure 1 This embodiment provides a pushbroom hyperspectral imaging device based on metasurface structure. The similarities with Embodiment 1 will not be repeated here. The differences will be described in detail below.

[0039] Please see the appendix Figure 1 In this embodiment, the cross-sectional shape of the dielectric pillar is at least one of a circle, a square, and a triangle. Of course, an L-shape or a C-shape can also be selected according to the actual situation to enhance the sensitivity to a specific polarization state. At the same time, the arrangement of several dielectric pillars is set to a periodic arrangement, a random arrangement, or a quasi-periodic arrangement.

[0040] During operation, when a periodic arrangement is used, several periodically arranged dielectric pillars are positioned according to a period determined by the desired narrowband beam splitting wavelength range. Setting the size of the dielectric pillars to be smaller than the target wavelength produces significant diffraction and resonance phenomena. The center-to-center distance between adjacent dielectric pillars is set as the sum of the ratio of the target wavelength to the effective refractive index of the dielectric pillar and a preset correction parameter. In practice, the correction parameter can be obtained through simulation optimization. When a random or quasi-periodic arrangement is used, the dimensions of the dielectric pillars are set to several different characteristic dimensions determined by the desired broadband beam splitting wavelength range. The positions and sizes of the dielectric pillars are arranged in a completely random manner within the background medium, or several dielectric pillars... The position and size of the columns are arranged in the background medium in a quasi-periodic manner, which avoids the dependence of periodic arrangement on specific wavelengths and enables efficient spectral dispersion over a wider frequency band, thereby improving the applicability. In actual operation, the height of the medium columns can be adjusted to further enrich the optical response modes of the metasurface spectral imaging system 3, reduce the influence of diffraction effects, and make the optical effect more uniform. At the same time, the quasi-periodic arrangement can avoid periodic repetition while maintaining a certain degree of order, thereby further improving the spectral dispersion performance over a wide frequency band. Ideally, the arrangement density and size of the medium columns can also be dynamically adjusted to create a gradual refractive index distribution, which can further improve the focusing and spectral dispersion effects provided by metasurface spectral imaging.

[0041] In this embodiment, dielectric pillars with different refractive indices and a background medium are used. Different combinations of dielectric pillar cross-sectional shapes and spacings are employed to cover the desired wavelength range for beam splitting. When periodically arranged dielectric pillars are used, a metasurface with a specific frequency response can be created, thereby efficiently separating light within the desired wavelength range. When randomly or quasi-periodicly arranged dielectric pillars are used, efficient beam splitting over a wider bandwidth can be achieved, and a uniform optical response can be provided over a wide bandwidth. Furthermore, using quasi-periodicly arranged dielectric pillars can further improve the beam splitting performance over a wide bandwidth, making it widely applicable and versatile.

[0042] As a further improvement of this embodiment, the metasurface component 31 is made by nano-etching or imprinting technology. In order to improve the spectral accuracy, the dielectric column is preferably titanium dioxide or silicon nitride with a high refractive index, while the background medium can be made of materials such as glass or polymer with a low refractive index, which can effectively enhance the resonance effect and reduce the absorption loss.

[0043] The beneficial technical effects of this embodiment include: the present invention, through the cooperation of the imaging lens, slit, metasurface beam splitting imaging system, sensor and image control board, is applicable to the wavelength range supporting deep ultraviolet, ultraviolet, visible light, near-infrared, short-wave infrared, mid-wave infrared and far-infrared bands, and can support some or all of the above bands or mixed bands. It has high spectral precision and can easily achieve nanometer or sub-nanometer spectral resolution. At the same time, it adopts a metasurface beam splitting imaging system that can realize collimation, beam splitting and focusing functions, which can achieve ultra-high precision beam splitting without reconstruction calculation. It also optimizes the optical path system, has a compact structure, small size and reduced number of parts, which facilitates deployment and can be put into use with only a small amount of debugging.

[0044] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art should understand that the present invention includes, but is not limited to, the contents described in the accompanying drawings and the specific embodiments above. Any modifications that do not depart from the functional and structural principles of the present invention will be included within the scope of the claims.

Claims

1. A pushbroom hyperspectral imaging device based on metasurface structure, characterized in that, include: An image-capturing lens (1) is used to collect light from the target area and focus it onto the slit (2); Slit (2) is used to limit the width of the incoming light; A metasurface beam-splitting imaging system (3) is used to achieve collimation, beam splitting and focusing functions through physical beam splitting. Sensor (4) is used to sense incident light within the corresponding wavelength range and output a digital analog signal; Image control board (5) is used to coordinate the entire imaging process and to acquire, process and transmit image signals from sensor (4); The imaging part of the imaging lens (1), the slit (2), the metasurface beam splitting imaging system (3) and the imaging part of the sensor (4) are connected along the direction of the light path extension. The sensor (4) is connected to the image control board (5) for data. The image control board (5) is connected to the corresponding external device for data through the transmission interface. After the imaging lens (1) captures the image of the target area, it acquires the light signal of the entire target area to focus the light on the slit (2). The slit (2) transmits the linear light part of the light to the metasurface beam splitting imaging system (3). The metasurface beam splitting imaging system (3) collimates, splits and focuses the linear light part and then acquires and focuses the light of the corresponding wavelength band to the imaging part of the sensor (4). The metasurface spectroscopic imaging system (3) includes at least one metasurface component (31), which includes several medium pillars with different refractive indices and a background medium, with the several medium pillars arranged in the background medium; The arrangement of several dielectric pillars is set to a periodic arrangement. The periodic arrangement of the several periodically arranged dielectric pillars is determined according to the period determined by the desired narrowband spectral wavelength range. The size of the dielectric pillar is set to be smaller than the target wavelength. The center distance between the dielectric pillar and the adjacent dielectric pillar is set to the sum of the ratio of the target wavelength to the effective refractive index of the dielectric pillar and a preset correction parameter.

2. The pushbroom hyperspectral imaging device based on metasurface structure according to claim 1, characterized in that: The array layout between several dielectric pillars is set as a one-dimensional linear array.

3. The pushbroom hyperspectral imaging device based on metasurface structure according to claim 1, characterized in that: The cross-sectional shape of the medium column is at least one of a circle, a square, and a triangle.

4. The pushbroom hyperspectral imaging device based on metasurface structure according to claim 1, characterized in that: The arrangement of the dielectric pillars is set to random or quasi-periodic arrangement, and the dimensions of the dielectric pillars are set to several different characteristic dimensions determined according to the required broadband spectral wavelength range.

5. A pushbroom hyperspectral imaging device based on a metasurface structure according to claim 4, characterized in that: The positions and sizes of several media columns are arranged in the background medium in a completely random manner.

6. The pushbroom hyperspectral imaging device based on metasurface structure according to claim 4, characterized in that: The positions and sizes of several medium columns are arranged in the background medium in a quasi-periodic manner.

7. The pushbroom hyperspectral imaging device based on metasurface structure according to claim 1, characterized in that: The slit (2) is positioned at the focal point of the imaging lens (1), and the imaging part of the sensor (4) is positioned at the focal point of the metasurface beamforming system (3).

8. The pushbroom hyperspectral imaging device based on metasurface structure according to claim 1, characterized in that: It also includes structural components, on which the imaging lens (1), slit (2), metasurface beamforming system (3) and sensor (4) are all fixedly mounted.

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