An active spectral modulation ultrafast laser and its hyperspectral detection system and method
By designing an active spectral modulation ultrafast laser and utilizing optical polarization modulation and nonlinear broadening techniques, the problems of low randomness and stability in existing spectral modulation techniques have been solved, achieving efficient spectral detection with high spectral resolution and long-distance spectral coverage.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-25
- Publication Date
- 2026-03-10
AI Technical Summary
Existing spectral modulation techniques suffer from problems such as low randomness of modulation spectra, unstable structure of filter materials, small field of view and short working distance, making it difficult to work stably in complex environments and lacking effective active lighting sources in low-light environments.
Design an active spectral modulation ultrafast laser, including an ultrafast pulsed laser, a primary polarization modulation module, a nonlinear broadening module, and a secondary polarization modulation module. The polarization state of each band of the spectrum is modulated by optical polarization modulation devices, and broadband modulation is achieved by combining nonlinear broadening technology. A hyperspectral imaging system is used for data screening and reconstruction.
It achieves high spectral resolution and long-distance spectral coverage with stable operation in complex environments, improves the flexibility and accuracy of spectral modulation, and is suitable for efficient hyperspectral detection.
Smart Images
Figure CN119812914B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of ultrafast laser design and hyperspectral imaging, and particularly relates to an active spectral modulation ultrafast laser and its hyperspectral detection method. Background Technology
[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.
[0003] Hyperspectral imaging is a three-dimensional information acquisition technology that combines optical imaging and spectral detection, and it is widely used in fields such as Earth remote sensing, medical diagnosis, environmental monitoring, life sciences, and precision agriculture. Compared with traditional hyperspectral imaging, computational spectral imaging technology based on broadband coding has advantages such as high spatial and spectral resolution, high signal-to-noise ratio, high light throughput, and small number of parameters, and represents a new direction for the development of hyperspectral imaging technology.
[0004] Among them, computational spectral imaging technology based on spectral modulation has advantages such as high spectral resolution, high data acquisition efficiency, and high flexibility and tunability. However, existing active and passive spectral modulation technologies based on tunable filters, quantum dot filters, and LED arrays each have their own drawbacks, such as low randomness of modulation spectra, unstable filter material structures, small field of view, and short working distance.
[0005] In specific and complex scenarios, hyperspectral imaging systems not only need to have stable operation in complex environments, but also require a wide spectral coverage and high spectral resolution. Furthermore, active illumination sources are indispensable in low-light environments. Summary of the Invention
[0006] To address at least one of the technical problems in the background art, the present invention provides an active spectral modulation ultrafast laser and its hyperspectral detection method. It designs an active illumination source with a wide spectral range, high spectral randomness, and high power, as well as its hyperspectral imaging system, to provide excellent spectral modulation capabilities, thereby simultaneously meeting the requirements of high spectral resolution, long working distance, and high robustness.
[0007] To achieve the above objectives, the present invention adopts the following technical solution:
[0008] A first aspect of the present invention provides an active spectral modulation ultrafast laser, comprising an ultrafast pulsed laser, a primary polarization modulation module, a nonlinear broadening module, and a secondary polarization modulation module;
[0009] The output of the ultrafast pulsed laser is connected to the input of the preliminary polarization modulation module, the output of the preliminary polarization modulation module is connected to the input of the nonlinear broadening module, and the output of the nonlinear broadening module is connected to the input of the secondary polarization modulation module.
[0010] The narrow-spectrum pulsed laser emitted by the ultrafast pulsed laser undergoes preliminary modulation of the polarization state of each wavelength band by the preliminary modulation module, and then enters the nonlinear broadening module for spectral broadening to obtain a broadband pulsed laser. The broadband pulsed laser emitted from the nonlinear broadening module enters the secondary polarization modulation module, where the polarization state of each spectrum is randomized before it is irradiated onto the target scene.
[0011] Furthermore, the primary polarization modulation module and the secondary polarization modulation module adopt the same structure, both including one or a combination of optical polarization modulation devices.
[0012] Furthermore, the nonlinear broadening module employs a nonlinear optical fiber, which is selected from the nonlinear optical fiber of the corresponding wavelength band of the ultrafast laser seed source.
[0013] Furthermore, the ultrafast pulsed laser includes pulsed lasers in the visible light band, near-infrared band, mid-infrared band, and terahertz band.
[0014] A second aspect of the present invention provides a hyperspectral imaging system for an actively modulated ultrafast laser, comprising a controller, a camera, and the actively modulated ultrafast laser described in the first aspect; the preliminary polarization modulation module, the secondary polarization modulation module, and the camera are respectively connected to the controller, and the controller includes a spectral data filtering module, a joint acquisition module, and a hyperspectral imaging module;
[0015] The spectral data filtering module is configured to: filter and obtain the optimal spectral dataset based on the spectral data output by the active spectral modulation ultrafast laser under various modulation parameters of the preliminary polarization modulation module and the secondary polarization modulation module.
[0016] The joint acquisition module is configured to: control the primary polarization modulation module and the secondary polarization modulation module to switch to the corresponding modulation parameters according to the optimal spectral dataset, and simultaneously acquire reflectance intensity images of the target scene under different modulation spectra;
[0017] The hyperspectral imaging module is configured to combine the reflectance intensity image and the corresponding spectral distribution to obtain a hyperspectral image of the target scene.
[0018] Furthermore, in the spectral data filtering module, the selection criterion for the optimal spectral dataset is as follows: the spectral structures with the lowest correlation to other spectral structures, calculated based on the cross-correlation algorithm, are selected as the optimal spectral dataset.
[0019] A third aspect of the present invention provides a hyperspectral imaging method based on an active spectral modulation ultrafast laser, comprising the following steps:
[0020] The optimal spectral dataset was obtained by filtering the spectral data output from the active spectral modulation ultrafast laser under various modulation parameters by the primary polarization modulation module and the secondary polarization modulation module.
[0021] Based on the optimal spectral dataset, the primary polarization modulation module and the secondary polarization modulation module are controlled to switch to the corresponding modulation parameters, while simultaneously acquiring reflectance intensity images of the target scene under different modulation spectra.
[0022] By combining the reflectance intensity image and the corresponding spectral distribution, a hyperspectral image of the target scene is obtained.
[0023] Furthermore, when calculating the hyperspectral image of the target scene by combining the reflectance intensity image and the corresponding spectral distribution, the spectral distribution of the target scene is inverted using a compressed sensing algorithm.
[0024] Furthermore, the reflectance intensity image of the target scene is as follows:
[0025]
[0026] Among them, P N (x,y) represents the target reflectivity information, S N (λ i The spectral distribution of the output after one modulation by an actively modulated ultrafast laser is O(x,y,λ). i ) represents the hyperspectral information of an object in the target scene within the modulation spectral range, N is the Nth spectral structure, and λ i Let be the i-th wavelength channel, x be the x-coordinate of the pixel, and y be the y-coordinate of the pixel.
[0027] A fourth aspect of the present invention provides a program product.
[0028] A program product includes a computer program that, when executed by a processor, implements the steps in the hyperspectral imaging method based on an active spectral modulation ultrafast laser as described in the third aspect.
[0029] Compared with the prior art, the beneficial effects of the present invention are:
[0030] 1. Compared to traditional spectral modulation methods, this invention significantly improves modulation speed and flexibility by using optical polarization modulation devices to modulate the polarization state of each spectral band. It can cover a wider wavelength range in a shorter time and achieve higher modulation accuracy. Furthermore, the system can operate stably in complex environments, avoiding the limitations imposed by the structural instability of filter materials, and enabling highly efficient hyperspectral detection.
[0031] 2. Compared with laser technologies used for spectral measurement, such as supercontinuum lasers and optical frequency comb-based spectral measurement technologies, this invention also has unique advantages. Compared with optical frequency comb-based spectral measurement technologies, this invention achieves wide-spectrum modulation without pursuing ultra-high spectral resolution. Instead, it achieves wide-spectrum modulation directly within the laser through nonlinear broadening technology. This allows the invention to generate spectral components in a wider wavelength range, thereby covering a wider tuning range.
[0032] Advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description
[0033] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.
[0034] Figure 1 This is a schematic diagram of the active spectral modulation ultrafast laser structure provided in an embodiment of the present invention;
[0035] Figure 2 This is a flowchart of a hyperspectral imaging method based on an active spectral modulation ultrafast laser provided in an embodiment of the present invention. Detailed Implementation
[0036] The present invention will be further described below with reference to the accompanying drawings and embodiments.
[0037] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.
[0038] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.
[0039] As mentioned in the background art, in specific and complex scenarios, hyperspectral imaging systems not only need to have stable operation capabilities in complex environments, but also require a wide spectral coverage and high spectral resolution. Furthermore, in low-light environments, active illumination sources are equally indispensable. Therefore, this invention designs an active illumination source and its hyperspectral imaging system with a wide spectral range, high spectral randomness, and high power to provide excellent spectral modulation capabilities, thereby simultaneously meeting the requirements of high spectral resolution, long working distance, and high robustness.
[0040] Example 1
[0041] like Figure 1 As shown, this embodiment provides an active spectral modulation ultrafast laser, including an ultrafast pulse laser, a primary polarization modulation module, a nonlinear broadening module, and a secondary polarization modulation module;
[0042] The output of the ultrafast pulsed laser is connected to the input of the preliminary polarization modulation module, the output of the preliminary polarization modulation module is connected to the input of the nonlinear broadening module, and the output of the nonlinear broadening module is connected to the input of the secondary polarization modulation module.
[0043] The narrow-spectrum pulsed laser emitted by the ultrafast pulsed laser is initially modulated by the preliminary modulation module to change the polarization state of each laser band. Then, it enters the nonlinear broadening module and becomes a broadband pulsed laser determined by the incident laser band and its polarization state. The broadband ultrafast pulsed laser emitted from the nonlinear broadening module enters the secondary polarization modulation module to randomize the polarization state of each spectrum. Subsequently, the laser passes through a polarizer and is emitted as linearly polarized light, illuminating the target scene, thus achieving more random spectral modulation.
[0044] In this embodiment, the ultrafast pulsed laser is a conventional ultrafast pulsed laser used to emit laser light, including ultrafast sources in the visible light band, near-infrared band, mid-infrared band, and even terahertz band. The single-pulse energy of this type of ultrafast laser is adjustable with the pump power.
[0045] The preliminary polarization modulation module may include one or a combination of optical polarization modulation devices such as a quarter-wave plate, a half-wave plate, a polarizing prism, and an electro-optic modulator.
[0046] Different input parameters of the optical polarization modulation module cause changes in the polarization state of the incident laser, thereby completing the initial modulation of the polarization state of each band component. The narrow-spectrum ultrafast pulse laser with changed polarization state is then coupled into the nonlinear broadening module.
[0047] In this embodiment, the nonlinear broadening module employs a nonlinear optical fiber, and the nonlinear optical fiber is selected from the spectral band corresponding to the ultrafast laser seed source. Due to nonlinear effects, the nonlinear optical fiber causes the laser to generate non-existent frequency bands, resulting in spectral broadening.
[0048] In this embodiment, the secondary polarization modulation module adopts the same structure as the primary polarization modulation module, including one or a combination of optical polarization modulation devices such as a quarter-wave plate, a half-wave plate, a polarizing prism, and an electro-optic modulator.
[0049] After the broadened pulsed laser is emitted from the nonlinear fiber, it enters the secondary polarization modulation module to further randomize the polarization state of the broadband laser. Subsequently, the laser passes through a polarizer and is emitted as linearly polarized light, achieving spectral modulation with higher randomness.
[0050] With the parameter settings of the optical polarization module used, the active spectral modulation ultrafast laser can generate broadband lasers with different spectral distributions. For example, by rotating the angle of the waveplate and changing the voltage applied to the crystal by the electro-optic modulator.
[0051] Example 2
[0052] This embodiment provides a hyperspectral imaging system based on an active spectral modulation ultrafast laser, including a controller, a camera, and the active spectral modulation ultrafast laser described in Embodiment 1; the preliminary polarization modulation module, the secondary polarization modulation module, and the camera are respectively connected to the controller, and the controller includes a spectral data filtering module, a joint acquisition module, and a hyperspectral imaging module;
[0053] The spectral data filtering module is configured to: filter and obtain the optimal spectral dataset based on the spectral data output by the active spectral modulation ultrafast laser under various modulation parameters of the preliminary polarization modulation module and the secondary polarization modulation module.
[0054] The joint acquisition module is configured to: control the primary polarization modulation module and the secondary polarization modulation module to switch to the corresponding modulation parameters according to the optimal spectral dataset, and simultaneously acquire reflectance intensity images of the target scene under different modulation spectra;
[0055] The hyperspectral imaging module is configured to combine the reflectance intensity image and the corresponding spectral distribution to obtain a hyperspectral image of the target scene.
[0056] In the spectral data filtering module, the selection criteria for the optimal spectral dataset are as follows: based on the cross-correlation algorithm, the correlation between different spectra is calculated, and the multiple sets of spectral structures with the lowest correlation with other spectral structures are selected as the optimal spectral set.
[0057] Example 3
[0058] like Figure 2 As shown, this embodiment provides a hyperspectral imaging method based on an actively modulated ultrafast laser, including the following steps:
[0059] Step 1: Based on the spectral data output by the active spectral modulation ultrafast laser from the primary polarization modulation module and the secondary polarization modulation module under various modulation parameters, the optimal spectral dataset is selected.
[0060] Step 2: Based on the optimal spectral dataset, control the primary polarization modulation module and the secondary polarization modulation module to switch to the corresponding modulation parameters, and simultaneously acquire reflectance intensity images of the target scene under different modulation spectra;
[0061] In this embodiment, the spectral distribution of the active spectral modulation ultrafast laser output is recorded under various modulation parameters of the primary polarization modulation module and the secondary polarization modulation module.
[0062] Subsequently, the spectrally modulated laser is irradiated onto the target object to be detected, and the polarization modulation process is connected to the acquisition camera using a synchronous control system.
[0063] After the parameters of the primary polarization modulation module and the secondary polarization modulation module are changed, the acquisition camera synchronously records the reflectivity intensity of the target scene under the spectral distribution of the target object;
[0064] Multiple spectral modulations and data acquisitions are completed by switching the selected parameters of the polarization modulation module multiple times.
[0065] Step 3: Combine the reflectance intensity image and the corresponding spectral distribution to obtain the hyperspectral image of the target scene.
[0066] In this embodiment, the selected spectral distribution and the collected data are fed into joint reconstruction, and the hyperspectral information of the target object is obtained by using a compressed sensing reconstruction algorithm.
[0067] The hyperspectral information of the target object is obtained by inverting using compressed sensing reconstruction algorithms, specifically including:
[0068] The spectral distribution of the output laser after one modulation cycle of the actively modulated ultrafast laser can be denoted as S. N (λ i ), where N is the Nth spectral structure. The hyperspectral information of objects in the target scene within the modulation spectral range can be denoted as O(x,y,λ).i Therefore, in the case of a laser emission spectral structure of S... N (λ i When the target scene reflectivity information is collected, it is as follows:
[0069]
[0070] Where, λ i Let be the i-th wavelength channel, x be the x-coordinate of the pixel, and y be the y-coordinate of the pixel.
[0071] At this point, the method is known to have the laser spectral structure S. N (λ i ) and target reflectivity information P N Substituting the above information into the compressed sensing reconstruction algorithm, we can retrieve the hyperspectral information O(x,y,λ) of the target object. i ).
[0072] In this embodiment, a compressed sensing algorithm suitable for spectral reconstruction is selected based on the spectral characteristics of different target objects.
[0073] The ADMM-TV algorithm will be used as an example for explanation:
[0074]
[0075] in, The estimated result for the target object O; TV(O) represents the regularization term for the sparsity constraint of O; α is the penalty parameter for balancing residuals and sparsity during the optimization process; This represents the l2 norm. The spatially independent spectral distribution of the target can be obtained using the method described above.
[0076] Therefore, by performing the above calculations on each pixel of the target, a spatial spectral data cube can be obtained. This method effectively transforms each pixel on the camera into a separate spectrometer, allowing for arbitrary selection of the spatial resolution of the imaging in experiments.
[0077] Finally, the spectral resolution achievable by the method and the number of spectral channels for hyperspectral imaging are explained in detail.
[0078] By collecting multiple sets of spectral distributions from the active spectral modulation laser and the reflectivity distribution of the target scene, compressed sensing calculations are used to reconstruct the spectral distribution of the target object.
[0079] Therefore, the highest spectral resolution that can be achieved is determined by the spectrometer used to acquire the spectrum.
[0080] The actual spectral resolution that can ultimately be achieved is determined by the signal-to-noise ratio during the system acquisition process. By increasing the image acquisition time, the signal-to-noise ratio can be greatly improved, thereby achieving hyperspectral detection with higher spectral resolution.
[0081] The number of spectral channels in the method is determined by the wide spectral range output by the active spectral modulation laser and the resolution of the spectrometer acquiring the spectral distribution. The number of spectral channels in the method is defined as an integer between the wide spectral range and the spectral resolution. Based on the achievable spectral resolution and the number of spectral channels, the method can be considered to meet the standards for hyperspectral imaging.
[0082] Example 4
[0083] This embodiment provides a program product, which is a computer program product, including a computer program. When the computer program is executed by a processor, it implements the steps in the hyperspectral imaging method based on an active spectral modulation ultrafast laser as described in Embodiment 3.
[0084] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of hardware embodiments, software embodiments, or embodiments combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage and optical storage) containing computer-usable program code.
[0085] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.
[0086] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.
[0087] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.
[0088] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, it can include the processes described in the embodiments of the above methods. The storage medium can be a magnetic disk, optical disk, read-only memory (ROM), or random access memory (RAM), etc.
[0089] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. An actively spectrally modulated ultrafast laser, characterized in that, The active spectrum modulation ultrafast laser comprises an ultrafast pulse laser, a preliminary polarization modulation module, a nonlinear broadening module and a secondary polarization modulation module. The output end of the ultrafast pulse laser is connected with the input end of the preliminary polarization modulation module, the output end of the preliminary polarization modulation module is connected with the input end of the nonlinear broadening module, and the output end of the nonlinear broadening module is connected with the input end of the secondary polarization modulation module. The narrow-spectrum pulse laser emitted by the ultrafast pulse laser is subjected to preliminary modulation of polarization states of lasers in each waveband by the preliminary modulation module, and then enters the nonlinear broadening module to obtain wide-spectrum pulse laser through spectral broadening.
2. An actively spectrally modulated ultrafast laser as claimed in claim 1, characterized in that, The preliminary polarization modulation module and the secondary polarization modulation module adopt the same structure and comprise one of optical polarization modulation devices or a combination of multiple devices.
3. An actively mode-locked ultrafast laser as claimed in claim 1, characterized in that The nonlinear broadening module adopts a nonlinear optical fiber, and the nonlinear optical fiber is selected according to the nonlinear optical fiber corresponding to the waveband of the ultrafast laser seed source.
4. An actively mode-locked ultrafast laser as claimed in claim 1, characterized in that The ultrafast pulse laser comprises pulse lasers in visible light waveband, near-infrared waveband, mid-infrared waveband and terahertz waveband.
5. A hyperspectral imaging system of an active spectral modulation ultrafast laser, characterized in that, The active spectrum modulation ultrafast laser comprises a controller, a camera and the active spectrum modulation ultrafast laser according to any one of claims 1-4, the preliminary polarization modulation module, the secondary polarization modulation module and the camera are connected to the controller, and the controller comprises a spectrum data screening module, a joint acquisition module and a hyperspectral imaging module. The spectrum data screening module is configured to screen an optimal spectrum data set according to spectrum data output by the active spectrum modulation ultrafast laser under each modulation parameter of the preliminary polarization modulation module and the secondary polarization modulation module, and the screening basis of the optimal spectrum data set is that several groups of spectrum structures with the lowest correlation with other spectrum structures calculated based on a cross-correlation algorithm are taken as the optimal spectrum data set. The joint acquisition module is configured to control the preliminary polarization modulation module and the secondary polarization modulation module to switch to corresponding modulation parameters according to the optimal spectrum data set, and simultaneously acquire reflectivity intensity images of the target scene under different modulation spectrums. The hyperspectral imaging module is configured to obtain a hyperspectral image of the target scene by combining the reflectivity intensity images and corresponding spectrum distributions.
6. A hyperspectral imaging method of an actively spectrally modulated ultrafast laser, characterized by, The method comprises the following steps: screening an optimal spectrum data set according to spectrum data output by the active spectrum modulation ultrafast laser under each modulation parameter of the preliminary polarization modulation module and the secondary polarization modulation module, and the screening basis of the optimal spectrum data set is that several groups of spectrum structures with the lowest correlation with other spectrum structures calculated based on a cross-correlation algorithm are taken as the optimal spectrum data set; controlling the preliminary polarization modulation module and the secondary polarization modulation module to switch to corresponding modulation parameters according to the optimal spectrum data set, and simultaneously acquiring reflectivity intensity images of the target scene under different modulation spectrums; combining the reflectivity intensity images and corresponding spectrum distributions to obtain a hyperspectral image of the target scene.
7. A method of hyperspectral imaging of an active spectroscopically modulated ultrafast laser as claimed in claim 6, wherein, The hyperspectral image of the target scene is calculated by using a compression sensing algorithm to inverse the spectral distribution of the target scene according to the reflectivity intensity image and the corresponding spectral distribution.
8. A method of hyperspectral imaging of an active spectroscopically modulated ultrafast laser as claimed in claim 6, wherein, The reflectivity intensity image of the target scene is as follows: ， wherein, is the target reflectivity information, is the spectral distribution of the active spectral modulation ultrafast laser to complete a modulation output, is the hyperspectral information of the object in the target scene to the modulation spectral range, is the first spectral structure, is the first wavelength channel, is the horizontal coordinate of the pixel point, is the vertical coordinate of the pixel point.
9. A program product, the program product being a computer program product comprising a computer program, characterized in that The computer program is executed by a processor to realize the steps in the hyperspectral imaging method of the active spectral modulation ultrafast laser according to any one of claims 6-8.