A kind of computing spectrometer and computing spectral reconstruction method, readable storage medium

Abstract

The present application provides a kind of computing spectrometer, comprising: laser, for providing calibration light source;Single-mode optical fiber, limit the mode distribution of incident light, for transmitting stable incident light to broadband filter part;Polarization controller, installed on single-mode optical fiber, so that incident light has unique polarization;Broadband filter part, placed in the tail end direction of single-mode optical fiber, the broadband filter part includes first broadband filter and second broadband filter, the first broadband filter and the second broadband filter are used alternately to split wave to be measured signal light;Transparent scattering medium, placed after the broadband filter part, so that the speckle pattern of incident light is obtained after scattering;Face array photoelectric detector.The beneficial effects of the present application are: using single-mode optical fiber to guide incident light, which can reduce the difficulty of reconstruction calculation and improve the bandwidth of broadband filter part, and using transparent scattering medium as the core device of spectrometer, which has the advantages of stable structure, low cost and simple system.

Description

TECHNICAL FIELD

[0001] The present application relates to a computational spectrometer, in particular to a computational spectrometer and a computational spectrum reconstruction method and a readable storage medium. BACKGROUND

[0002] Spectrometers are widely used in scientific research and industrial production. Traditional spectrometers usually use gratings or prisms for light splitting, but gratings and prisms have defects such as large volume, high cost, and limited resolution. In recent years, with the proposal of computational spectrometers, the resolution can be improved and the device volume can be greatly reduced from the perspective of algorithm and device design, realizing a small spectrometer suitable for production application. Unlike the one-to-one simple mapping of traditional spectrometers from spectrum to space, computational spectrometers are usually one-to-many complex mapping.

[0003] At present, there are many implementation schemes for the complex mapping of computational spectrometers. Computational spectrometers based on speckle reconstruction have the advantages of ultra-compactness and low cost. The core of speckle reconstruction is to map the spectral information into a complex speckle pattern after passing through a scattering medium. The first to appear is to use multi-mode optical fibers, single-mode optical fibers, etc. to form a speckle pattern, but the fiber structure is extremely unstable and is easily affected by the environment. Disorder photonic crystals, multi-mode spiral waveguides, etc. can also be used, but such structures require complex design and have high preparation costs.

[0004] Therefore, it is still challenging to research a small spectrometer with stable structure, low cost, simple system, and commercial spectrometer resolution. SUMMARY

[0005] In order to solve the problems in the prior art, the present application provides a computational spectrometer and a computational spectrum reconstruction method and a readable storage medium.

[0006] The present application provides a computational spectrometer, comprising:

[0007] A laser for providing a calibration light source;

[0008] A single-mode optical fiber for limiting the mode distribution of incident light and transmitting stable incident light to a broadband filter part;

[0009] A polarization controller installed on the single-mode optical fiber to make the incident light have a unique polarization;

[0010] A broadband filter part placed in the tail end direction of the single-mode optical fiber, the broadband filter part comprising a first broadband filter and a second broadband filter, the first broadband filter and the second broadband filter being used alternately to split the signal light to be measured;

[0011] A transparent scattering medium placed after the broadband filter part to scatter the incident light to obtain a speckle pattern;

[0012] A surface array photodetector is arranged in the speckle pattern direction for receiving and recording the scattering pattern.

[0013] As a further improvement of the present application, the laser employs a wideband tunable laser or a laser covering the near-infrared band (e.g. 900-1600 nm).

[0014] As a further improvement of the present application, the computing spectrometer further comprises a computer having an executable computing program stored thereon for acquiring the predetermined calibration information of the surface array photodetector and performing spectral reconstruction calculation to obtain the input spectrum.

[0015] As a further improvement of the present application, the first wideband filter and the second wideband filter are used to divide the incident light into different bands, and the first wideband filter and the second wideband filter are located at the same position of the computing spectrometer and are alternately used by a wheel.

[0016] As a further improvement of the present application, the first wideband filter has a light transmission range of 400-600 nm, and the second wideband filter has a light transmission range of 600-800 nm.

[0017] As a further improvement of the present application, the transparent scattering medium employs an object having a random scattering mechanism.

[0018] As a further improvement of the present application, the surface array photodetector employs a silicon-based detector in the visible light band.

[0019] As a further improvement of the present application, the surface array photodetector employs an InGaAs material detector in the infrared band.

[0020] As a further improvement of the present application, the output of the calibration light source is single-wavelength light.

[0021] The present application also provides a computing spectral reconstruction method based on the computing spectrometer, which comprises the following steps:

[0022] S1, recording a calibration speckle pattern,

[0023] The wideband tunable laser scans the output, and the surface array photodetector records the calibration speckle pattern. During the calibration process, the wideband filter part is not used, and only the scanning wavelength is divided into two groups according to different bands.

[0024] S2, obtaining a transmission matrix,

[0025] The calibration speckle pattern is processed on the computer, a calibration matrix is obtained by mean filtering and equal-interval sampling, and a transmission matrix is obtained.

[0026] S3, solving the input spectrum,

[0027] Input the signal light to be measured, alternately use the first wideband filter and the second wideband filter to obtain a signal vector to be measured, and solve the input spectrum.

[0028] As a further improvement of the application, step S1 comprises: using the wideband tunable laser to scan a series of calibration light sources in a set spectral range with a set step length, and using the area array photodetector to record a series of calibration speckle patterns corresponding to the calibration light sources, that is, at least one calibration speckle pattern corresponding to each wavelength.

[0029] As a further improvement of the application, step S2 comprises: processing the calibration speckle patterns on the computer, dividing the calibration speckle patterns into two groups, one group corresponding to the wavelength range of the first wideband filter, and the other group corresponding to the wavelength range of the second wideband filter, obtaining two groups of calibration matrices by equal interval sampling method after mean filtering pretreatment, and combining the transmission matrices of the two groups by combining the spectra of the calibration light sources.

[0030] As a further improvement of the application, step S3 comprises: inputting the signal light to be measured from a single-mode optical fiber, alternately using the first wideband filter and the second wideband filter to collect two speckle patterns corresponding to the signal light to be measured, and obtaining two groups of signal vectors to be measured by equal interval sampling method in step S2, respectively applying the corresponding transmission matrices, combining the spectrum vectors of the two groups by combining the compression sensing principle and the convex optimization solving method, and obtaining the input spectrum of the signal light to be measured by combining the results.

[0031] The application further provides a readable storage medium, wherein the readable storage medium stores execution instructions, and the execution instructions are executed by a processor to implement the computing spectrum reconstruction method.

[0032] The application has the advantages that: the application provides a computing spectrometer, a computing spectrum reconstruction method and a readable storage medium, uses a single-mode optical fiber to guide incident light, reduces the reconstruction calculation difficulty and improves the bandwidth of the wideband filter part, and uses a transparent scattering medium as a core device of the spectrometer, so that the application has the advantages of stable structure, low cost and simple system; in addition, the computing spectrometer uses two wideband filters to first separate the incident light beam in space, so that the corresponding speckle patterns have more obvious differences, the contrast of the speckle images is improved, and the calculation error is reduced; at the same time, the introduction of the two wideband filters divides the speckle pictures into two groups for reconstruction calculation, reduces the dimension of the calibration matrix, greatly reduces the calculation amount of the spectrum reconstruction, and more importantly, breaks through the bandwidth limitation of the reconstruction of the computing spectrometer, and makes the performance of the computing spectrometer closer to that of a commercial spectrometer. BRIEF DESCRIPTION OF DRAWINGS

[0033] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description only constitute some embodiments of the present application, and other solutions can be obtained by those skilled in the art without creative effort on the basis of these drawings.

[0034] Figure 1 The structure schematic diagram of the computing spectrometer based on the transparent disordered medium and the filter structure provided by the present application.

[0035] Figure 2 The flow chart of the spectrum reconstruction method in the present application.

[0036] Figure 3 The narrowband spectrum reconstruction diagram of the present application.

[0037] Figure 4 The broadband spectrum reconstruction diagram of the present application.

[0038] In the figure: 1, broadband tunable laser; 2, single-mode optical fiber; 3, polarization controller; 4, incident light beam; 5, broadband filter part; 6, transparent scattering medium; 7, area array photoelectric detector; 8, computer. DETAILED DESCRIPTION

[0039] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0040] In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the scope of protection of the present application. In addition, the terms "first", "second" and the like are only for the purpose of description and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features with "first", "second" and the like can explicitly or implicitly include one or more of the features. In the description of the present application, unless otherwise specified, the meaning of "a plurality of" is two or more.

[0041] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0042] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0043] like Figure 1 As shown, this invention provides a computational spectrometer, which is a computational spectrometer based on a transparent disordered medium (also known as a transparent scattering medium) and a filter structure, mainly comprising:

[0044] Broadband tunable laser 1, used to provide a calibration light source;

[0045] Single-mode fiber 2 restricts the mode distribution of incident light 4 and is used to transmit stable incident light 4 to the broadband filter section.

[0046] A polarization controller 3 is installed on the single-mode fiber 2 to ensure that the incident light has a unique polarization.

[0047] The broadband filtering section 5 is placed at the tail end of the single-mode optical fiber 2. The broadband filtering section 5 includes two broadband filters, namely a first broadband filter and a second broadband filter. The first broadband filter and the second broadband filter are used alternately to split the signal light to be tested.

[0048] A transparent scattering medium 6 is placed after the broadband filter section 5 to scatter the incident light and obtain a speckle pattern.

[0049] An array photodetector 7 is positioned along the direction of the speckle pattern to receive and record the scattering pattern.

[0050] The computational spectrometer also includes a computer 8, which stores an executable calculation program for obtaining pre-calibration information of the area array photodetector 7 and performing spectral reconstruction calculations to obtain the input spectrum.

[0051] The present invention provides a computational spectrometer, which features low computational complexity, low cost and high resolution.

[0052] This invention adds two broadband filters to perform wave division processing on the wavelength to be reconstructed in time, which not only improves the reconstruction accuracy of the computational spectrometer, but also significantly reduces the computational complexity, and is expected to realize a more reliable and low-cost spectrometer.

[0053] In one of the examples of the present application: the output of the light source is single-wavelength light, and the half-peak width and scanning interval can be selected according to the application.

[0054] In one of the examples of the present application: the first broadband filter and the second broadband filter are used to divide the incident light into different wavebands, and the first broadband filter and the second broadband filter are located at the same position of the computing spectrometer and are alternately used by a rotating disc.

[0055] In one of the examples of the present application: the first broadband filter and the second broadband filter are alternately used in the reconstruction of the spectrum, and when used in the visible light waveband, the light transmission range of the first broadband filter is 400-600 nm, and the light transmission range of the second broadband filter is 600-800 nm, and the light transmission range of the two broadband filters can be adjusted according to the application.

[0056] In one of the examples of the present application: the transparent scattering medium 6 adopts an object with a random scattering mechanism, which can be ground glass, a diffraction pinhole, or other objects with a random scattering mechanism.

[0057] In one of the examples of the present application: the area array photoelectric detector 7 adopts a silicon-based detector in the visible light waveband, and the detector material can be appropriately selected according to different applications.

[0058] In one of the examples of the present application: the area array photoelectric detector 7 adopts an InGaAs material detector in the infrared waveband, and the detector material can be appropriately selected according to different applications.

[0059] Referring to Figure 1 , the present application is a computing spectrometer based on a transparent disordered medium and a filter structure. For near-infrared applications, the broadband tunable laser 1 can be replaced with a laser covering the near-infrared waveband such as 900-1600 nm, and the area array photoelectric detector 7 can be replaced with an InGaAs material detector,

[0060] Referring to Figure 2 , Figure 2 The present application also provides a computing spectrum reconstruction method based on the computing spectrometer, which comprises the following steps:

[0061] S1, recording a calibration speckle pattern,

[0062] The broadband tunable laser 1 scans the output, and the area array photoelectric detector 7 records the calibration speckle pattern.

[0063] S2, obtaining a transmission matrix,

[0064] The calibration speckle pattern is processed on the computer 8, a calibration matrix is obtained through mean filtering and equal interval sampling, and a transmission matrix is solved;

[0065] S3, solving an input spectrum,

[0066] An input signal light is input, the first wideband filter and the second wideband filter are alternately used, an input signal vector is obtained, and an input spectrum is solved.

[0067] In one of the examples of the present application, step S1 comprises: using the wideband tunable laser 1 to scan a series of calibration light sources in a set spectral range with a set step length, and using the area array photoelectric detector 7 to record a series of calibration speckle patterns corresponding to the series of calibration light sources, that is, at least one calibration speckle pattern corresponding to each wavelength.

[0068] In one of the examples of the present application, step S2 comprises: processing the calibration speckle pattern on the computer, dividing the calibration speckle pattern into two groups, dividing the calibration speckle pattern into one group in the wavelength range corresponding to the first wideband filter, and dividing the calibration speckle pattern into another group in the wavelength range corresponding to the second wideband filter, obtaining two groups of calibration matrices through equal interval sampling method after mean filtering preprocessing, and solving two groups of transmission matrices in combination with the spectrum of the calibration light source.

[0069] In one of the examples of the present application, step S3 comprises: inputting the input signal light from a single-mode optical fiber, alternately using the first wideband filter and the second wideband filter, collecting two speckle patterns corresponding to the input signal light, and obtaining two groups of input signal vectors by using the equal interval sampling method in step S2, respectively applying the corresponding transmission matrix, solving two groups of spectrum vectors by using the principle of compressed sensing and the convex optimization solving method, and combining the results to obtain the input spectrum of the input signal light.

[0070] In one of the examples of the present application, step S2 comprises the following sub-steps:

[0071] Step S21: image processing of cropping and adjusting;

[0072] Step S22: background noise removal processing;

[0073] Step S23: Gaussian filtering noise removal processing;

[0074] Step S24: equal interval sampling of taking a plurality of pixels as a sampling point to obtain a calibration matrix composed of column vectors;

[0075] For example, 9 pixels are taken as a sampling point for equal interval sampling to obtain a calibration matrix composed of column vectors, but the present application is not limited thereto;

[0076] Step S25: combining the input light source intensity and the calibration matrix, calculating the corresponding inverse matrix to obtain the transmission matrix.

[0077] In one of the examples of the present application, step S3 comprises:

[0078] In combination with the principle of compressed sensing, the spectral channel in the calibration stage is N, and the sampling channel corresponding to each wavelength is M, M is less than N; at the same time, the convex optimization solving method comprises L2 norm regularization solving and orthogonal matching pursuit.

[0079] A readable storage medium, wherein the readable storage medium stores execution instructions, and the execution instructions are executed by a processor to implement the method for calculating spectral reconstruction.

[0080] As shown in Figure 3 and Figure 4 The two figures both represent the recovery of the preset spectral signal by the spectrometer. The detected output speckle is taken as a special fingerprint, and the input spectral signal is reconstructed and solved by using the convex optimization algorithm. It can be seen from the result that the discrete spectrum and the continuous spectrum can both be reconstructed and recovered, and the spectral information of different intensities can be accurately recovered.

[0081] The above is a further detailed description of the present application in combination with the specific preferred embodiments, and the specific implementation of the present application cannot be limited to these descriptions. For ordinary skilled persons in the technical field to which the present application belongs, a number of simple deductions or substitutions can be made without departing from the concept of the present application, and all of them should be regarded as falling within the protection scope of the present application.

Claims

1. A method of computing spectral reconstruction, characterized by: A computational spectrometer is provided, comprising: Laser, used to provide a calibration light source; Single-mode fiber restricts the mode distribution of incident light and is used to transmit stable incident light to the broadband filter section. A polarization controller is installed on the single-mode fiber to ensure that the incident light has a unique polarization; The broadband filtering section is placed at the tail end of the single-mode optical fiber. The broadband filtering section includes a first broadband filter and a second broadband filter. The first broadband filter and the second broadband filter are used alternately to split the signal light under test. A transparent scattering medium is placed after the broadband filter section to scatter the incident light and obtain a speckle pattern. An array photodetector is positioned along the direction of the speckle pattern to receive and record the speckle pattern; Based on the aforementioned computational spectrometer, the following steps are performed: S1. Record the calibration speckle pattern. The laser scans and outputs, and the area array photodetector records the calibration speckle pattern. During the calibration process, the broadband filter is not used. S2. Find the transmission matrix. The calibration speckle pattern is processed on a computer, and the calibration matrix is ​​obtained by mean filtering and equal-interval sampling. The transmission matrix is ​​then calculated. S3. Solve for the input spectrum. Input the signal light to be measured, and alternately use the first broadband filter and the second broadband filter to obtain the signal vector to be measured, and solve for the input spectrum; Step S1 includes: using the laser to scan and output a series of calibration light sources within a set spectral range at a set step size, and using the area array photodetector to record the calibration speckle patterns corresponding to the series of calibration light sources, i.e., at least one calibration speckle pattern corresponds to each wavelength; Step S2 includes: processing the calibration speckle patterns on a computer, dividing the calibration speckle patterns into two groups, one group corresponding to the wavelength range of the first broadband filter and the other group corresponding to the wavelength range of the second broadband filter, obtaining two sets of calibration matrices by means filtering preprocessing and equal-interval sampling of the calibration speckle patterns, and solving for two sets of transmission matrices by combining the spectrum of the calibration light sources; Step S3 includes: inputting the signal light to be tested from a single-mode fiber, alternately using the first broadband filter and the second broadband filter, acquiring two speckle patterns corresponding to the signal light to be tested, and obtaining two sets of signal vectors to be tested by using the equal-interval sampling method in step S2, applying the corresponding transmission matrices respectively, and obtaining two sets of spectral vectors by combining the compressed sensing principle and convex optimization solution method, and merging the results to obtain the input spectrum of the signal light to be tested.

2. The method of computing a spectral reconstruction of claim 1, wherein: The computational spectrometer also includes a computer that stores an executable calculation program for acquiring pre-calibration information of the area array photodetector and performing spectral reconstruction calculations to obtain the input spectrum.

3. The method of claim 1, wherein: The incident light is divided into wavelength bands using the first broadband filter and the second broadband filter. The first broadband filter and the second broadband filter are located at the same position in the computational spectrometer and are used alternately by a wheel.

4. The method of claim 1, wherein: The first broadband filter has a light transmission range of 400-600 nm, and the second broadband filter has a light transmission range of 600-800 nm.

5. The method of claim 1, wherein: The transparent scattering medium adopts an object with a random scattering mechanism.

6. The method of claim 1, wherein: The area array photodetector adopts a silicon-based detector in a visible light wave band or an InGaAs material detector in an infrared wave band.

7. The method of claim 1, wherein: The laser adopts a wideband tunable laser or a laser covering a near-infrared wave band.

8. A readable storage medium characterized by: The readable storage medium stores execution instructions, and the execution instructions are executed by the processor to implement the computing spectrum reconstruction method in any one of claims 1 to 7.

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