Aperture coded spectrum detection device based on compressed sensing

Abstract

The present invention provides an aperture coded spectrum detection device based on compressed sensing, which solves the problem that both the dispersion type and the interference type spectrum detection technologies in the existing spectrum detection technologies have certain deficiencies. The device comprises an imaging mirror, a filter array, a spatial light modulator, a unit detector and a data processing unit arranged in sequence along the light beam direction; the imaging mirror is used to image the target at a primary image plane position; the filter array is used to modulate the spectrum information of the target so that the wavelengths of the light at different aperture positions are different; the spatial light modulator is used to encode the modulated spectrum information; the unit detector is used to receive the encoded image signal; the data processing unit is used to decode the encoded image signal received by the unit detector, and the spectrum data of the target can be restored.

Description

Technical Field

[0001] The present invention belongs to the field of spectrum detection technology, and in particular relates to an aperture coded spectrum detection device based on compressed sensing. Background Art

[0002] The spectrum of a substance is considered to be the "fingerprint" of the substance. For most substances, its spectral information has clear material characteristics. Therefore, spectral detection is often used in many aspects such as material component identification and component content detection. For example, infrared Fourier interference spectroscopy technology is widely used in gas component detection and gas concentration detection, Raman spectroscopy is used in drug and chemical component and content detection, and spectral detection technology is also widely used in food safety, agriculture and forestry, air and water quality monitoring, etc.

[0003] As for spectral detection technology, current spectrometers mainly achieve detection through two methods: dispersion and interference. Among them, the dispersion type spectrometer disperses the target spectrum to a linear or planar array detector through a dispersion device such as a grating or prism, thereby directly obtaining the target's spectral information. The interference type spectrometer uses a unit detector to perform time-sharing sampling of signals under different optical path differences, and indirectly obtains the target's spectral information by performing Fourier transform on the periodic sampling signal.

[0004] However, both the dispersion type and interference type spectral detection technologies have certain shortcomings. For the dispersion type spectrometer, firstly, the detector of the spectrometer is a linear array or planar array detector, which is relatively easy to implement in the visible light band, but in the infrared band, on the one hand, the infrared linear array or planar array detector technology is not mature, the detector specifications are small, the price is high, and the performance is poor, which limits the performance and indicators of the spectrometer; on the other hand, the infrared spectrometer wants to achieve high-precision and high signal-to-noise ratio detection capabilities, which places more stringent requirements on the detector performance; secondly, the signal energy of a single spectral band after the dispersion type spectrometer is split is weak, resulting in a lower response intensity of the detector to the signal. This effect is more serious in the infrared band. Obviously, the sensitivity and signal-to-noise ratio of the dispersive infrared spectrometer system are very low; as for the interference spectrometer, the spatial modulation interference spectrometer requires an array detector, the quality of the collected signal is affected by the detector process, and the price is high; the time modulation interference spectrometer, because the signal is an interference fringe, to ensure the integrity of the signal, high frame rate sampling is required, and the spectral resolution of the system is positively correlated with the optical path length. In the case of a large optical path difference, the collected signal not only has a relatively long time period, but also a large amount of collected signal data, which brings certain difficulties to the storage and real-time processing of the data. Summary of the invention

[0005] In order to solve the technical problems that both the dispersion type and interference type spectral detection technologies have certain deficiencies in the existing spectral detection technologies, the present invention provides an aperture coded spectral detection technology and device based on compressed sensing.

[0006] To achieve the above purpose, the technical solution provided by the present invention is:

[0007] An aperture coded spectral detection device based on compressed sensing is special in that it includes a data processing unit, an imaging mirror, a filter array, a spatial light modulator, and a unit detector which are sequentially arranged along the direction of the light beam; the imaging mirror is used to image the target at a primary image plane position; the filter array is used to modulate the spectral information of the target so that the wavelengths of light at different aperture positions are different; the spatial light modulator is used to encode the modulated spectral information; the unit detector is used to receive the encoded image signal; the data processing unit is used to decode the encoded image signal received by the unit detector, so as to restore the spectral data of the target.

[0008] Furthermore, the data processing unit is used to process the coded detection signal sequence with a sparsity of K.

[0009] Furthermore, the filter array is a linear gradient filter array or a narrow-band filter array.

[0010] Furthermore, the spatial light modulator is a digital micromirror array.

[0011] Furthermore, the spatial light modulator is a liquid crystal spatial light modulator.

[0012] Furthermore, the spatial light modulator is a mechanical template for mask etching.

[0013] Compared with the prior art, the advantages of the present invention are:

[0014] 1. The spectrum detection device of the present invention only needs to add a filter array and a spatial light modulator between the lens and the detector, so that the overall structure is relatively simple;

[0015] Compared with linear array and planar array detectors, unit detectors have better detection performance and detection speed. The compression of multiple channels further improves the detection sensitivity and signal-to-noise ratio of the system.

[0016] The use of unit detectors has technical and cost advantages in infrared, terahertz and other bands, and can achieve high-resolution spectral detection.

[0017] Compared with array detectors, unit detectors have better response capabilities and dynamic range, and also have extremely high sampling speeds, which improves data quality and real-time data output capabilities.

[0018] 2. The spectrum detection device of the present invention encodes the modulated spectrum information through a spatial light modulator, which can greatly reduce the signal sampling period and sampling times, reduce the size of data collected in a single period, reduce the hardware requirements for data collection, transmission, and storage, and reduce the cost of the instrument.

[0019] 3. Based on the combination of prior knowledge and detection coding, the spectrum detection device of the present invention can directly realize the identification and classification of specific targets through the detection device. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a light path diagram of the aperture coded spectrum detection device based on compressed sensing of the present invention;

[0021] The reference numerals are as follows:

[0022] 1-object plane, 2-imaging mirror, 3-filter array, 4-spatial light modulator, 5-unit detector. DETAILED DESCRIPTION

[0023] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0024] Compressed sensing (CS), also known as compressed sampling, is a new mathematical theory. By fully exploring the redundancy of the signal, a linear, non-adaptive global observation of the original signal is performed to obtain a small amount of observed signals, and then the original signal is accurately reconstructed through a reconstruction algorithm. Compressed sensing technology is an emerging information acquisition and processing theory. This theory uses the prior knowledge of signal sparsity to achieve high-precision data restoration with very few samplings. The research on compressed sensing comes from multiple fields such as approximation theory, convex optimization, random matrix theory, and signal processing. It has been applied to radar and microscopes. Reduce the sampling rate and increase the resolution in these applications to improve the user experience. Increase data transmission, improve imaging quality, and reduce exposure time.

[0025] The present invention combines compressed sensing technology with filter spectroscopic technology, and spatially encodes and spectrally modulates the aperture of a traditional camera to achieve compressed sampling of the signal. Compared with the direct dispersion and interference scheme, it can be achieved through a unit detector 5, and the compression of multi-channel data is achieved through aperture coding, and the signal sampling is greatly reduced through the design of the compressed sensing scheme. The present invention places a filter array in the optical path to achieve spectral modulation, and places a coding template in the optical path to achieve coding of different spectral bands, and then compresses the coded square to achieve compressed sensing imaging. Through the compressed sensing restoration algorithm, the target spectral information can be restored through a small amount of sampled data.

[0026] like Figure 1 As shown, an aperture coded spectral detection device based on compressed sensing includes an imaging mirror 2, a filter array 3, a spatial light modulator 4, and a unit detector 5 which are sequentially arranged along the direction of the light beam, and also includes a data processing unit for processing the information collected by the unit detector; firstly, the aperture light field of the target is spectrally modulated by the filter array 3, and then, the different channels after the spectral modulation are coded and modulated by the spatial light modulator 4, and the design of the coding template satisfies sparse sampling, and then the modulated light field information is compressed to the unit detector 5, so as to realize the aperture coded spectral detection technology based on the principle of compressed sensing.

[0027] The detection target of the detection device in this embodiment is a point source target, and the field of view of the system is very small. The object-image relationship is as follows: Figure 1 As shown, the left side of the imaging mirror 2 represents the object plane 1;

[0028] The imaging mirror 2 is composed of one or more groups of lenses, and is used to image the target at the primary image plane position. Its aperture diaphragm coincides with the position of the filter array 3, so as to achieve the convergence of the object surface light information;

[0029] The filter array 3 is used to modulate the spectral information of the target so that the wavelengths of light passing through different aperture positions are different. The filter array 3 is a linear gradient filter array or a narrow-band filter array;

[0030] The spatial light modulator 4 is used to encode the modulated spectral information. Its encoding template can be designed according to sparse coding, and can also be designed in combination with the prior spectral characteristic information of the target to increase the signal acquisition and recovery capabilities. The spatial light modulator 4 is a digital micromirror array or a liquid crystal spatial light modulator or a mechanical template etched by a mask;

[0031] The unit detector 5 is used to receive the encoded image signal and realize the reception of the acquisition signal. Compared with the area array detector, the unit detector 5 has the characteristics of high sensitivity, high dynamic range, high response rate, low price, etc. and can be applied to the visible, near infrared, thermal infrared and terahertz bands;

[0032] The data processing unit is used to decode the encoded image signal received by the unit detector, and can restore the spectral data of the target. Preferably, the encoded detection signal sequence with a sparsity of K is collected and processed to achieve signal restoration.

[0033] The spectral detection device of this embodiment has a simple and compact structure and can be miniaturized and lightweight. Compared with the traditional dispersion spectrometer and Fourier interferometer spectrometer, only the filter array 3 and the spatial light modulator 4 need to be added between the lens and the detector, making the system structure very simple and easy to design and develop.

[0034] Compared with the dispersion spectrometer, the spectrum detection device of this embodiment can achieve high sensitivity and high signal-to-noise ratio detection. First, the unit detector 5 has better detection performance and detection speed than the linear array and planar array detectors. Second, the compressed imaging of multiple channels further improves the detection sensitivity and signal-to-noise ratio of the system.

[0035] Compared with the Fourier interferometer spectrometer, the spectral detection device of this embodiment can greatly reduce the signal sampling period and sampling times by adopting the technical solution of compressed sensing, reduce the size of data collected in a single period, reduce the hardware requirements for data collection, transmission, and storage, reduce the instrument cost, increase the difficulty and complexity of online data processing, and enhance the system's real-time spectral data processing capability.

[0036] Compared with the dispersive spectrometer, the spectral detection device of this embodiment has technical and cost advantages in the infrared band, terahertz band and other bands. Since the existing infrared band planar array and linear array detector technologies are relatively immature, the detector specifications are small, the price is expensive, and compared with the unit detector 5, the performance gap is large; the spectral detection device of this embodiment only uses the unit detector 5 to achieve high-resolution spectral detection.

[0037] The spectrum detection device of this embodiment uses compressed sensing technology to greatly reduce the amount of data that needs to be collected. Compared with Fourier spectroscopy technology, its reconstruction process is more efficient, and it can realize real-time online data processing, which can meet the application of high-time spectrum detection. And this solution can further realize accurate detection and identification of targets under the premise of prior knowledge.

[0038] The above is only a description of the preferred implementation mode of the present invention, and the technical solution of the present invention is not limited thereto. Any known deformation made by those skilled in the art on the basis of the main technical concept of the present invention belongs to the technical scope to be protected by the present invention.

Claims

1. An aperture coded spectrum detection device based on compressed sensing, characterized in that: It comprises a data processing unit, an imaging mirror (2) arranged in sequence along the direction of the light beam, a filter array (3), a spatial light modulator (4), and a unit detector (5); The imaging mirror (2) is used to image the target at a primary image plane position; The filter array (3) is used to modulate the spectral information of the target so that the wavelengths of light at different aperture positions are different; The spatial light modulator (4) is used to encode the modulated spectral information, and then compress the encoded light field information and transmit it to the unit detector (5); the design of the encoding template satisfies sparse sampling, and the sparsity is K; The unit detector (5) is used to receive the encoded image signal; The data processing unit is used to decode the encoded image signal with a sparsity of K received by the unit detector (5), and can restore the spectral data of the target.

2. The aperture coded spectrum detection device based on compressed sensing according to claim 1, characterized in that: The filter array (3) is a linear gradient filter array or a narrow-band filter array.

3. The aperture coded spectrum detection device based on compressed sensing according to claim 1 or 2, characterized in that: The spatial light modulator (4) is a digital micromirror array.

4. The aperture coded spectrum detection device based on compressed sensing according to claim 1 or 2, characterized in that: The spatial light modulator (4) is a liquid crystal spatial light modulator.

5. The aperture coded spectrum detection device based on compressed sensing according to claim 1 or 2, characterized in that: The spatial light modulator (4) is a mechanical template for mask etching.

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