An infrared snapshot spectral imaging system using coded filters

Abstract

The present invention discloses an infrared snapshot spectral imaging system based on a coding filter, comprising a telescope, an aperture, a collimator, a filter array, a microlens array and a detector array. The light emitted by the light source passes through the telescope, the aperture, the collimator, the filter array and the microlens array in sequence, and is finally received by the detector. The filter in the filter array is a coding filter, and the coding filter randomly transmits the infrared signal according to the band. By encoding the spectrum, a spectral aliasing signal with a high signal-to-noise ratio is obtained, and then the spectral aliasing signal is restored by using information decoding technology to obtain a fine infrared spectrum. The present invention realizes high resolution, high efficiency, band selectivity, flexibility and strong anti-interference ability.

Description

Technical Field

[0001] The invention belongs to the technical field of infrared imaging, and in particular relates to an infrared snapshot spectral imaging system of a coding filter. Background Art

[0002] Infrared is an electromagnetic wave with a wavelength range of 760nm-1mm, also called infrared. According to Planck's blackbody radiation law, any object with an absolute temperature higher than absolute zero can radiate electromagnetic waves, and the wavelength and energy of the radiated electromagnetic waves are closely related to the temperature of the emitting source.

[0003] The infrared snapshot spectral imaging system is a multi-dimensional information acquisition method that combines imaging technology and spectral technology. It can perform non-invasive imaging of targets in multiple spectral bands and generate a spectral data cube containing spatial and spectral information. The infrared snapshot spectral imaging system achieves efficient and accurate capture of infrared bands by integrating advanced optical components, filter arrays, and high-performance detectors. This system can simultaneously obtain the spatial image and spectral information of the target, providing strong technical support for scientific research, environmental monitoring, security monitoring and other fields.

[0004] In practical applications, the infrared snapshot spectral imaging system has shown great potential. For example, in the field of environmental monitoring, the system can be used to track the distribution and diffusion of pollutants, providing a scientific basis for environmental protection; in the field of security monitoring, it can identify camouflaged or hidden targets and improve the accuracy and reliability of the monitoring system; in addition, the system is also widely used in medical diagnosis, materials science, chemical analysis and other fields, providing strong technical support for the development of various industries. The filter used in the snapshot multi-aperture spectral imaging technology based on infrared microlens array multi-channel imaging is a traditional filter, which only allows signals in a specific band to pass through, and the signal passing efficiency is relatively low: the transmittance of the traditional filter in a specific wavelength range may not be as high as that of the new optical filter, which will affect the spectral resolution and imaging quality of the system. In addition, the bandwidth of the traditional filter may be wide, resulting in mutual interference between lights of different wavelengths, further reducing the spectral resolution; due to the wide bandwidth of the traditional filter, the amount of data collected may be large and contain more noise and interference information. This will increase the difficulty of data processing and analysis, requiring more complex algorithms and longer processing time. Summary of the invention

[0005] The object of the present invention is to provide an infrared snapshot spectral imaging system based on a coding filter in view of the problems in the prior art.

[0006] To this end, the above-mentioned purpose of the present invention is achieved through the following technical solutions:

[0007] An infrared snapshot spectral imaging system based on a coding filter includes a telescope, an aperture collimator, a filter array, a microlens array, and a detector array. The light emitted by the light source passes through the telescope, the aperture, the collimator, the filter array, the microlens array in sequence, and is finally received by the detector.

[0008] The filters in the filter array are coded filters, which randomly transmit infrared signals according to the wavelength bands, and obtain spectral aliasing signals with high signal-to-noise ratio by encoding the spectrum. The spectral aliasing signals are then restored using information decoding technology to obtain a fine infrared spectrum.

[0009] While adopting the above technical solutions, the present invention may also adopt or combine the following technical solutions:

[0010] As the preferred technical solution of the present invention: the light emitted by the light source passes through the telescope, the aperture, the collimator, and reaches the filter array and the lens array. The detailed design indicators are as follows: the spectral range is set at 7 to 14 microns, the system focal length is f / 21.6mm, the field of view is 13.5°×10.8°, the sub-aperture is 1.2, the sub-aperture detector core surface uses an area of ​​384×307.2 yuan, the size is 4.608mm×3.6864mm, the spatial resolution is set to 0.56m@1Km, the modulation transfer function MTF is not less than 0.4@20.8lp / mm, and the distortion is not higher than 2%.

[0011] As a preferred technical solution of the present invention: the spectral range of the telescope is set to 7 to 14 microns; the field of view is set to 10°×8°; the focal length is 71.9 mm; the F number is set to 1.2; the image quality setting requirements are that the diffuse spot is within the Airy spot, the distortion is not higher than 1.1%, and the average optical efficiency is not lower than 70%.

[0012] As a preferred technical solution of the present invention: the spectral range of the optical collimator is set to 7 to 14 microns; the field of view, i.e., the aperture, is set to 12.5mm×10mm; the focal length is f / 24.6mm; the F number is set to 1.25; the image quality setting requirements are that the diffuse spot is within the Airy spot, the distortion is not higher than 1%, and the average optical efficiency is not lower than 70%.

[0013] As a preferred technical solution of the present invention: in the array module, the filter array is located before the microlens array, and the specific design parameters are: array scale: 3×3, sub-aperture corresponding core surface: 426.7 yuan×341.3 yuan, sub-aperture F#: 1.2, sub-lens focal length: ~7.1mm, sub-aperture image quality: MTF not less than 0.4@20.81p / mm, array lens size in the microlens array: 15.36mm×12.288mm, material: GE-GE.

[0014] As a preferred technical solution of the present invention: spectrum coding adopts band coding technology.

[0015] As a preferred technical solution of the present invention: the information decoding technology adopts compressed sensing technology.

[0016] As a preferred technical solution of the present invention: the system is placed in a temperature control box, the temperature is kept constant and filled with nitrogen to avoid the influence of water vapor, and an external controller is responsible for the communication link and power supply between the modules.

[0017] Compared with the prior art, the infrared snapshot spectral imaging system based on the coding filter of the present invention has the following beneficial effects: it is used to improve the spectral resolution of the infrared multi-aperture snapshot imaging spectral system. The system adopts a snapshot multi-aperture spectral imaging technology based on multi-channel imaging of an infrared microlens array, and introduces a coding filter therein to randomly transmit the infrared signal according to the band. By encoding the spectrum, a spectral aliasing signal with a high signal-to-noise ratio is obtained. Subsequently, these signals are restored using information decoding technologies such as compressed sensing to obtain a fine infrared spectrum. Compared with traditional methods, this system can significantly improve the resolution and sensitivity of the imaging spectrum while ensuring a good signal-to-noise ratio. Finally, a computational multi-aperture snapshot high spectral resolution imaging system based on spectral aliasing unmixing imaging is realized, which has broad application prospects and application value.

[0018] The compressed sensing technology used in the present invention does not require uniform sampling according to the traditional Nyquist theorem, but can collect far fewer samples than the number required by the traditional method, and reconstruct the signal through a compression algorithm. This method can save bandwidth and storage space during data collection and transmission, thereby improving the efficiency and performance of the system.

[0019] Compared with the traditional method, the infrared snapshot spectral imaging system based on the coding filter of the present invention can significantly improve the resolution and sensitivity of the imaging spectrum while ensuring a good signal-to-noise ratio. Finally, a computational multi-aperture snapshot high-spectral resolution imaging system based on spectral aliasing unmixing imaging is realized, which has broad application prospects and application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is an overall system diagram of an infrared snapshot spectral imaging system based on a coding filter of the present invention;

[0021] Figure 2 Schematic diagram of the imaging optical path of the present invention;

[0022] Figure 3 The present invention is a flow chart of an infrared snapshot spectral imaging method based on a coding filter. DETAILED DESCRIPTION

[0023] The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.

[0024] The present invention provides an infrared snapshot spectral imaging system based on a coding filter, which is used to improve the spectral resolution of an infrared multi-aperture snapshot imaging spectral system. The technical solution of the present invention is:

[0025] An infrared snapshot spectral imaging system based on a coding filter, comprising a telescope, an aperture, a collimator, a coding filter, a microlens array, and a detector array

[0026] The optical path of the imaging system is set as follows: the light emitted by the light source passes through the telescope, the aperture, the collimator, the filter array, the microlens array in sequence, and is finally received by the detector.

[0027] Among them, the light source provides the initial light signal; the telescope is used to collimate the light beam so that the light propagates in parallel or nearly parallel to reduce aberrations and improve the imaging quality of the system; the aperture limits the size and shape of the light beam, controls the light flux entering the system, and helps define the field of view of the system; the collimator adjusts and optimizes the beam path to ensure that the light enters the subsequent components in the correct direction and angle; the filter array selectively transmits light of specific wavelengths and filters out unwanted wavelengths, thereby improving the contrast and clarity of the image. Microlens array: composed of multiple tiny lenses, each of which can focus light independently, usually used to correct aberrations, improve resolution or achieve special imaging effects; the detector receives the light signal processed by the above components and converts it into an electrical signal.

[0028] Among them, the coding filter is located in the filter array, and the wavelength band of the infrared signal allowed to pass through by the coding filter is random. The wavelength band allowed to pass through by the coding filter becomes wider, which greatly improves the transmittance of the infrared signal.

[0029] Furthermore, the infrared snapshot spectral imaging system based on the coding filter adopts the snapshot multi-aperture spectral imaging technology based on the infrared microlens array multi-channel imaging. The filter used in this imaging technology is a traditional filter, which only allows signals of a specific band to pass through. After replacing the traditional filter with the coding filter, due to the characteristics of the coding filter, the band allowed to pass through becomes wider, which greatly improves the passing efficiency of signals of different bands.

[0030] Furthermore, the light emitted by the light source or the infrared signal emitted by the signal source will pass through the telescope system, aperture, relay system, filter array, microlens array in sequence, and finally reach the detector array. The filter array and lens array connected together are called a multi-aperture array.

[0031] Furthermore, when encoding the spectrum, a band coding technology may be used, and a spectrum aliasing signal with a high signal-to-noise ratio may be obtained after encoding.

[0032] Furthermore, the compressed sensing decoding technology is used to restore the spectral aliasing signal to obtain a fine infrared spectrum, thereby significantly improving the resolution of the imaging spectrum. Finally, a computational multi-aperture snapshot high spectral resolution imaging system based on spectral aliasing unmixing imaging is realized.

[0033] After the present invention replaces the traditional filter with the coded filter, due to the characteristics of the coded filter, the wavelength band of the infrared signal allowed to pass through by the coded filter is random, and the wavelength band allowed to pass through by the coded filter becomes wider, which greatly improves the passing efficiency of signals in different wavelength bands.

[0034] Spectral coding is a technology that uses the frequency, wavelength and color of light to encode information. The present invention uses coding techniques such as band coding, which converts light of different bands into signals with specific coding rules. This coding can take various forms, such as binary coding, Gray code coding or other custom coding. After coding, a spectral aliasing signal with a high signal-to-noise ratio can be obtained. When designing spectral coding, it is necessary to determine the required communication bandwidth and color resolution. These parameters will determine the accuracy and information capacity of the coding. Next, select or design an appropriate coding algorithm that can effectively convert data into spectral signals.

[0035] Traditional signal acquisition methods usually sample according to the Nyquist theorem, that is, the sampling frequency is at least twice the signal bandwidth. However, in many practical applications, signals are usually sparse or have certain structural properties, which means that there are only a few non-zero elements in the signal or there is a certain structure.

[0036] Compared with the prior art, the infrared snapshot spectral imaging system based on the coding filter of the present invention has the following advantages:

[0037] High resolution and high efficiency: The microlens array and multi-aperture design jointly improve the system's resolution and detection efficiency, and the snapshot imaging method enables the system to capture high-quality images in a short time;

[0038] Band selectivity and flexibility: The introduction of coded filters enables the system to transmit or block infrared light of a specific band as needed, thereby achieving band selection;

[0039] By replacing or adjusting the coding filter, the system can easily adapt to different detection needs and application scenarios;

[0040] Anti-interference ability: The random transmission characteristics of the coded filter help reduce the impact of environmental noise and interference on the system and improve the signal-to-noise ratio of the image.

[0041] The infrared snapshot spectral imaging system based on the coding filter of the present invention realizes high resolution, high efficiency, band selectivity, flexibility and strong anti-interference ability.

[0042] Example 1

[0043] like Figure 1 As shown, the infrared snapshot spectral imaging system based on the coding filter of the present invention adopts the snapshot multi-aperture spectral imaging technology based on the multi-channel imaging of the infrared microlens array. In order to suppress the influence of the environmental temperature drift on the system, the system is placed in a temperature control box 8, the temperature is kept constant and filled with nitrogen to avoid the influence of water vapor. The external controller 9 is responsible for the communication link and power supply between the modules. The telescope system includes a telescope, the relay system includes a collimator, and the array module includes a filter array, a lens array and a detector array.

[0044] The temperature control box 8 is equipped with a pan / tilt system 10, which supports and controls an infrared snapshot spectral imaging system based on a coding filter to achieve precise positioning and tracking.

[0045] Nitrogen is filled into the temperature control box 8 to remove oxygen and moisture in the air to maintain a constant environment in the temperature control box 8. A non-refrigeration component 12 is provided in the temperature control box to achieve temperature control. The temperature in the temperature control box 8 is controlled at -2°C ± 0.2°C. An air valve 11 is provided on the temperature control box 8 to control the amount of gas entering or exhausting the temperature control box, thereby achieving control of the environment of the temperature control box 8.

[0046] like Figure 1 , Figure 2 As shown in the overall design of the optical system, the light source filters out light of other wavelengths through the infrared window 13, and only allows infrared light to pass through the telescope 1, the aperture 2, and the collimator 3 to reach the filter array 4 and the lens array 5. The detailed design indicators are as follows: the spectral range is set at 7 to 14 microns, the system focal length is f / 21.6mm, the field of view is 13.5°×10.8°, the sub-aperture is 1.2, the sub-aperture detector core surface uses an area of ​​384×307.2 yuan, the size is 4.608mm×3.6864mm, the spatial resolution is set to 0.56m@1Km, the MTF is not less than 0.4@20.81p / mm, and the distortion is not higher than 2%.

[0047] The detailed design parameters of the optical telescope are as follows: the spectral range is set to 7 to 14 microns; the field of view is set to 10°×8°; the focal length is 71.9mm; the F number is set to 1.2; the image quality setting requirements are that the diffuse spot is within the Airy disk, the distortion is no higher than 1.1%, and the average optical efficiency is no less than 70%.

[0048] The detailed design parameters of the optical collimator are as follows: the spectral range is set to 7 to 14 microns; the field of view, i.e., the aperture, is set to 12.5mm×10mm; the focal length is f / 24.6mm; the F number is set to 1.25; and the image quality setting requirements are that the diffuse spot is within the Airy spot, the distortion is not higher than 1%, and the average optical efficiency is not lower than 70%.

[0049] In the present invention, the array module includes a filter array and a microlens array, wherein the filter array is located before the microlens array, and the specific design parameters are: array scale: 3×3, sub-aperture corresponding core surface: 426.7 yuan×341.3 yuan, sub-aperture F#: 1.2, sub-lens focal length: ~7.1mm, sub-aperture image quality: MTF not less than 0.4@20.81p / mm, array lens size: 15.36mm×12.288mm, material: GE-GE.

[0050] like Figure 3 As shown, an infrared snapshot spectral imaging method based on a coding filter is implemented using the above system, which includes:

[0051] Step 1: Replace the traditional filters in the filter array with coded filters, and randomly transmit the infrared signal through the filters according to the wavelength band, thereby improving the sensitivity of the imaging spectrum;

[0052] Step 2, by encoding the spectrum, a spectrum aliasing signal with a high signal-to-noise ratio is obtained;

[0053] Step three, use information decoding technology such as compressed sensing to restore the aliased signal, thereby obtaining a detailed infrared spectrum.

[0054] The infrared snapshot spectral imaging system based on the coding filter adopts the snapshot multi-aperture spectral imaging technology based on the infrared microlens array multi-channel imaging. The filter used in this imaging technology is a traditional filter, which only allows signals of a specific band to pass through. After replacing the traditional filter with the coding filter, due to the characteristics of the coding filter, the band allowed to pass through becomes wider, which greatly improves the passing efficiency of signals of different bands.

[0055] The light emitted by the light source or the infrared signal emitted by the signal source will pass through the telescope system, aperture, relay system, filter array, microlens array in sequence, and finally reach the detector array. The filter array and lens array connected together are called a multi-aperture array.

[0056] In step 2, the spectrum is encoded by using encoding techniques such as band encoding, which converts light of different bands into signals with specific encoding rules. This encoding can be in various forms, such as binary encoding, Gray code encoding or other custom encoding. After encoding, a spectrum aliasing signal with a high signal-to-noise ratio can be obtained.

[0057] The information decoding technology in step three, in step two, an aliased signal with a high signal-to-noise ratio is obtained, and information decoding technologies such as compressed sensing can be used. The traditional signal acquisition method is usually sampled according to the Nyquist theorem, that is, the sampling frequency is at least twice the signal bandwidth. However, in many practical applications, the signal is usually sparse or has a certain structural property, which means that there are only a few non-zero elements in the signal or there is a certain specific structure. The compressed sensing technology does not need to be uniformly sampled according to the traditional Nyquist theorem, but can collect far fewer samples than the number required by the traditional method, and reconstruct the signal through a compression algorithm. This method can save bandwidth and storage space during data acquisition and transmission, thereby improving the efficiency and performance of the system. The spectral aliasing signal is restored using compressed sensing decoding technology to obtain a fine infrared spectrum, thereby significantly improving the resolution of the imaging spectrum. Finally, a computational multi-aperture snapshot high spectral resolution imaging system based on spectral aliasing unmixing imaging is realized.

[0058] Compared with traditional methods, this system can significantly improve the resolution and sensitivity of imaging spectra while ensuring a good signal-to-noise ratio. Finally, a computational multi-aperture snapshot high-spectral resolution imaging system based on spectral aliasing unmixing imaging is realized, which has broad application prospects and application value. The obtained infrared spectrum can be used in the field of gas detection, and the absorption peak can be identified through the spectrum to judge the gas.

[0059] The above-mentioned specific implementation methods are used to explain the present invention and are only preferred embodiments of the present invention, rather than limiting the present invention. Any modifications, equivalent substitutions, improvements, etc. made to the present invention within the spirit of the present invention and the protection scope of the claims shall fall within the protection scope of the present invention.

Claims

1. An infrared snapshot spectral imaging system based on a coding filter, characterized in that: It includes a telescope, an aperture, a collimator, a filter array, a microlens array and a detector array. The light emitted by the light source passes through the telescope, the aperture, the collimator, the filter array, the microlens array in sequence, and is finally received by the detector. The filter in the filter array is a coded filter. The coded filter randomly transmits the infrared signal according to the band, and obtains a spectral aliasing signal with a high signal-to-noise ratio by encoding the spectrum. Subsequently, the spectral aliasing signal is restored using information decoding technology to obtain a fine infrared spectrum.

2. The infrared snapshot spectral imaging system based on coding filter according to claim 1, characterized in that: The light emitted by the light source passes through the telescope, aperture, collimator, and reaches the filter array and lens array. The detailed design indicators are as follows: the spectral range is set at 7 to 14 microns, the system focal length is f / 21.6mm, the field of view is 13.5°×10.8°, the sub-aperture is 1.2, the sub-aperture detector core surface uses an area of ​​384×307.2 yuan, the size is 4.608mm×3.6864mm, the spatial resolution is set to 0.56m@1Km, the modulation transfer function MTF is not less than 0.4@20.8lp / mm, and the distortion is not higher than 2%.

3. The infrared snapshot spectral imaging system based on coding filter according to claim 1, characterized in that: The spectral range of the telescope is set to 7 to 14 microns; the field of view is set to 10°×8°; the focal length is 71.9mm; the F number is set to 1.2; the image quality setting requirements are that the diffuse spot is within the Airy disk, the distortion is no higher than 1.1%, and the average optical efficiency is no less than 70%.

4. The infrared snapshot spectral imaging system based on coding filter according to claim 1, characterized in that: The spectral range of the optical collimator is set to 7 to 14 microns; the field of view, i.e., the aperture diameter, is set to 12.5mm×10mm; the focal length is f / 24.6mm; the F number is set to 1.25; the image quality setting requirements are that the diffuse spot is within the Airy spot, the distortion is not higher than 1%, and the average optical efficiency is not lower than 70%.

5. The infrared snapshot spectral imaging system based on coding filter according to claim 1, characterized in that: In the array module, the filter array is located before the microlens array. The specific design parameters are: array scale: 3×3, sub-aperture corresponding core surface: 426.7 yuan × 341.3 yuan, sub-aperture F#: 1.2, sub-lens focal length: ~7.1mm, sub-aperture image quality: MTF not less than 0.4@20.8lp / mm, array lens size in the microlens array: 15.36mm×12.288mm, material: GE-GE.

6. The infrared snapshot spectral imaging system based on coding filter according to claim 1, characterized in that: Spectral coding uses band coding technology.

7. The infrared snapshot spectral imaging system based on coding filter according to claim 1, characterized in that: The information decoding technology adopts compressed sensing technology.

8. The infrared snapshot spectral imaging system based on coding filter according to claim 1, characterized in that: The system is placed in a temperature-controlled box to keep a constant temperature and filled with nitrogen to avoid the influence of water vapor. An external controller is responsible for the communication link and power supply between the modules.

Images