Active spectrum modulation ultrafast laser and hyperspectral detection system and method thereof

Abstract

The invention belongs to the field of ultrafast laser design and hyperspectral imaging, and provides an active spectrum modulation ultrafast laser and a hyperspectral detection system and method thereof, and the technical scheme is that the active spectrum modulation ultrafast laser comprises an ultrafast pulse laser, a primary polarization modulation module, a nonlinear broadening module and a secondary polarization modulation module; narrow-spectrum pulse laser emitted by the ultrafast pulse laser enters the nonlinear broadening module to be subjected to spectrum broadening to obtain wide-spectrum pulse laser after being subjected to preliminary modulation of the polarization state of laser of all wave bands through the preliminary modulation module, and the wide-spectrum pulse laser emitted by the nonlinear broadening module enters the secondary polarization modulation module to be subjected to spectrum broadening to obtain wide-spectrum pulse laser. And after randomizing the polarization state of each spectrum, irradiating the spectrums to a target scene. After the spectrum is modulated, the camera is controlled to collect the reflectivity intensity information of the target scene, and after irradiation and image collection of multiple groups of selected spectrum structures are completed, hyperspectral detection of the target scene is achieved in combination with the measured spectrum distribution and the corresponding reflectivity information.

Description

Technical Field

[0001] The present invention belongs to the field of ultrafast laser design and hyperspectral imaging, and in particular relates to an active spectral modulation ultrafast laser and a hyperspectral detection method thereof. Background Art

[0002] The statements in this section merely provide 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. It is widely used in earth remote sensing, medical diagnosis, environmental monitoring, life sciences, precision agriculture and other fields. Compared with traditional hyperspectral imaging, computational spectral imaging technology based on wide spectrum coding has the advantages of high spatial and spectral resolution, high signal-to-noise ratio, high light flux and small number, and is a new development direction of hyperspectral imaging technology.

[0004] Among them, computational spectral imaging technology based on spectral modulation has the advantages of high spectral resolution, high data acquisition efficiency, high flexibility and adjustability. However, the existing active and passive spectral modulation technologies based on tunable filters, quantum dot filters and LED arrays have their own shortcomings, such as low randomness of modulation spectrum, unstable structure of filter materials, small field of view and short working distance.

[0005] In specific and complex scenarios, the hyperspectral imaging system is not only required to have stable working capabilities in complex environments, but also to have wide spectral coverage and high spectral resolution. In addition, in low-light environments, active lighting sources are also indispensable. Summary of the invention

[0006] In order to solve at least one technical problem existing in the above-mentioned background technology, the present invention provides an active spectral modulation ultrafast laser and a hyperspectral detection method thereof, which designs an active illumination light source with a wide spectral range, high spectral randomness and high power and a hyperspectral imaging system thereof to provide excellent spectral modulation capability, thereby simultaneously meeting the requirements of high spectral resolution, long working distance and high robustness.

[0007] In order to achieve the above object, 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 pulse laser, a preliminary polarization modulation module, a nonlinear broadening module and a secondary polarization modulation module;

[0009] The output end of the ultrafast pulse laser is connected to the input end of the preliminary polarization modulation module, the output end of the preliminary polarization modulation module is connected to the input end of the nonlinear broadening module, and the output end of the nonlinear broadening module is connected to the input end of the secondary polarization modulation module;

[0010] The narrow spectrum pulse laser emitted by the ultrafast pulse laser is subjected to preliminary modulation of the polarization state of each band of laser light by the preliminary modulation module, and then enters the nonlinear broadening module for spectrum broadening to obtain a wide spectrum pulse laser. The wide spectrum pulse laser emitted by the nonlinear broadening module enters the secondary polarization modulation module, randomizes the polarization state of each spectrum, and then irradiates the target scene.

[0011] Furthermore, the preliminary polarization modulation module and the secondary polarization modulation module adopt the same structure, and both include one or a combination of multiple optical polarization modulation devices.

[0012] Furthermore, the nonlinear broadening module uses a nonlinear optical fiber, and the nonlinear optical fiber is a nonlinear optical fiber with a wavelength band corresponding to the ultrafast laser seed source.

[0013] Furthermore, the ultrafast pulse laser includes pulse lasers in the visible light band, near infrared band, mid-infrared band and terahertz band.

[0014] The second aspect of the present invention provides a hyperspectral imaging system of an active spectral modulation ultrafast laser, comprising a controller, a camera and the active spectral modulation 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 comprises a spectral data screening module, a joint acquisition module and a hyperspectral imaging module;

[0015] The spectral data screening module is configured to: screen and obtain an optimal spectral data set according to 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 preliminary polarization modulation module and the secondary polarization modulation module to switch to corresponding modulation parameters according to the optimal spectral data set, and simultaneously acquire reflectivity 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 screening module, the screening basis for the optimal spectral data set is: taking several groups of spectral structures with the lowest correlation with other spectral structures calculated based on the cross-correlation algorithm as the optimal spectral data sets.

[0019] A third aspect of the present invention provides a hyperspectral imaging method based on active spectral modulation ultrafast laser, comprising the following steps:

[0020] The optimal spectral data set is screened out according to the spectral data outputted by the active spectral modulation ultrafast laser under various modulation parameters of the primary polarization modulation module and the secondary polarization modulation module;

[0021] Controlling the primary polarization modulation module and the secondary polarization modulation module to switch to corresponding modulation parameters according to the optimal spectral data set, and simultaneously collecting reflectance intensity images of the target scene under different modulation spectra;

[0022] The reflectance intensity image and the corresponding spectral distribution are combined to obtain a hyperspectral image of the target scene.

[0023] Furthermore, when the reflectance intensity image and the corresponding spectral distribution are combined to calculate the hyperspectral image of the target scene, the spectral distribution of the target scene is inverted using the compressed sensing algorithm.

[0024] Furthermore, the reflectivity intensity image of the target scene is:

[0025]

[0026] Among them, P N (x, y) is the target reflectivity information, S N (λ i ) is the spectral distribution of the active spectral modulation ultrafast laser after completing a modulation output, O(x, y, λ i ) is the hyperspectral information of the object in the target scene within the modulation spectrum range, N is the Nth spectral structure, λ i is the i-th wavelength channel, x is the horizontal coordinate of the pixel, and y is the vertical coordinate of the pixel.

[0027] A fourth aspect of the present invention provides a program product.

[0028] A program product includes a computer program, which, when executed by a processor, implements the steps of the hyperspectral imaging method based on active spectral modulation of ultrafast lasers as described in the third aspect.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] 1. Compared with the traditional spectral modulation method, the present invention significantly improves the modulation speed and flexibility by using optical polarization modulation devices to modulate the polarization state of each band of the spectrum, can cover a wider wavelength range in a shorter time, and has higher modulation accuracy. In addition, the system can still work stably in complex environments, avoiding the limitations caused by the structural instability of the filter material, and can achieve efficient hyperspectral detection.

[0031] 2. Compared with laser technologies used for spectral measurement, such as supercontinuous wave lasers and spectral measurement technologies based on optical frequency combs, the present invention also has unique advantages. Compared with spectral measurement technologies based on optical frequency combs, while achieving wide spectrum modulation, the present invention no longer pursues ultra-high spectral resolution, but directly achieves wide spectrum modulation in the laser through nonlinear broadening technology. This enables the present invention to generate spectral components in a wider wavelength range, thereby covering a wider tuning range.

[0032] Advantages of additional aspects of the present invention will be given in part in the following description, and in part will become obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0034] Figure 1 Schematic diagram of the structure of an active spectral modulation ultrafast laser provided by an embodiment of the present invention;

[0035] Figure 2 It is a flow chart of a hyperspectral imaging method based on active spectral modulation ultrafast laser provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0036] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0037] It should be noted that the following detailed descriptions are all illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0038] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0039] In view of the specific and complex scenes mentioned in the background technology, the hyperspectral imaging system is not only required to have the ability to work stably in complex environments, but also the system is required to have a wide spectral coverage and high spectral resolution. In addition, in a low-light environment, an active lighting source is also indispensable. Therefore, the present invention designs an active lighting source with a wide spectral range, high spectral randomness and high power and a hyperspectral imaging system thereof to provide excellent spectral modulation capabilities, thereby simultaneously meeting the requirements of high spectral resolution, long working distance and high robustness.

[0040] Embodiment 1

[0041] like Figure 1 As shown, this embodiment provides an active spectral modulation ultrafast laser, including an ultrafast pulse laser, a preliminary polarization modulation module, a nonlinear broadening module, and a secondary polarization modulation module;

[0042] The output end of the ultrafast pulse laser is connected to the input end of the preliminary polarization modulation module, the output end of the preliminary polarization modulation module is connected to the input end of the nonlinear broadening module, and the output end of the nonlinear broadening module is connected to the input end of the secondary polarization modulation module;

[0043] The narrow spectrum pulse laser emitted by the ultrafast pulse laser undergoes preliminary modulation of the polarization state of each band of laser light in the preliminary modulation module and then enters the nonlinear broadening module to become a wide spectrum pulse laser determined by the incident laser band and its polarization state. The wide spectrum ultrafast pulse laser emitted by 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 in the state of linearly polarized light and irradiates the target scene, thereby achieving a more random spectrum modulation.

[0044] In this embodiment, the ultrafast pulse laser uses a conventional ultrafast pulse laser for emitting laser light, including ultrafast light 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 polarization prism and an electro-optical modulator;

[0046] Different input parameters of the optical polarization modulation module cause the polarization state of the incident laser to change, thereby completing the preliminary modulation of the polarization state of each band component. The narrow spectrum ultrafast pulse laser with changed polarization state is coupled into the nonlinear broadening module.

[0047] In this embodiment, the nonlinear broadening module uses a nonlinear optical fiber, and the nonlinear optical fiber uses a spectral band corresponding to an ultrafast laser seed source. Due to the nonlinear effect of the nonlinear optical fiber, the laser generates a non-existent frequency band, resulting in spectrum 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 polarization prism and an electro-optical modulator;

[0049] After the broadened pulse laser is emitted from the nonlinear optical fiber, it enters the secondary polarization modulation module to further randomize the polarization state of the wide-spectrum laser. The laser then passes through a polarizer and is emitted as linearly polarized light, achieving more random spectral modulation.

[0050] Under the parameter setting of the optical polarization module used, the active spectrum modulated ultrafast laser can generate wide spectrum laser with different spectral distributions, for example, by rotating the angle of the wave plate and changing the voltage applied to the crystal by the electro-optic modulator.

[0051] Embodiment 2

[0052] This embodiment provides a hyperspectral imaging system based on an active spectral modulation ultrafast laser, comprising 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 comprises a spectral data screening module, a joint acquisition module and a hyperspectral imaging module;

[0053] The spectral data screening module is configured to: screen and obtain an optimal spectral data set according to 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 preliminary polarization modulation module and the secondary polarization modulation module to switch to corresponding modulation parameters according to the optimal spectral data set, and simultaneously acquire reflectivity 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 screening module, the screening basis for the optimal spectral data set is: based on the cross-correlation algorithm, the correlation between different spectra is calculated, and multiple groups of spectral structures with the lowest correlation with other spectral structures are selected as the optimal spectral set.

[0057] Embodiment 3

[0058] like Figure 2 As shown, this embodiment provides a hyperspectral imaging method based on active spectral modulation ultrafast laser, comprising the following steps:

[0059] Step 1: Screening and obtaining the optimal spectral data set based on the spectral data output by the active spectral modulation ultrafast laser under various modulation parameters of the primary polarization modulation module and the secondary polarization modulation module;

[0060] Step 2: Control the preliminary polarization modulation module and the secondary polarization modulation module to switch to corresponding modulation parameters according to the optimal spectral data set, and simultaneously collect reflectance intensity images of the target scene under different modulation spectra;

[0061] In this embodiment, the spectrum distribution of the active spectral modulation ultrafast laser output under various modulation parameters of the preliminary polarization modulation module and the secondary polarization modulation module is recorded;

[0062] Subsequently, the spectrally modulated laser light 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 controlled to be changed, the acquisition camera synchronously records the reflectivity intensity of the target scene of the target object under the spectral distribution;

[0064] Multiple spectral modulation and data collection are completed by multiple switching of the parameters selected by the polarization modulation module;

[0065] Step 3: Combine the reflectance intensity image and the corresponding spectral distribution to obtain a hyperspectral image of the target scene.

[0066] In this embodiment, the selected spectral distribution and the collected data are put into joint reconstruction, and the hyperspectral information of the target object is obtained by inversion using a compressed sensing reconstruction algorithm;

[0067] The hyperspectral information of the target object is obtained by inverting the compressed sensing reconstruction algorithm, including:

[0068] The spectrum distribution of the active spectrum modulation ultrafast laser after completing one modulation output can be recorded as S N (λ i ), where N is the Nth spectral structure. The hyperspectral information of the object in the target scene within the modulation spectrum range can be recorded as O(x, y, λi ). Therefore, the laser emission spectrum structure is S N (λ i ), the collected target scene reflectivity information is:

[0069]

[0070] Among them, λ i is the i-th wavelength channel, x is the horizontal coordinate of the pixel, and y is the vertical coordinate of the pixel.

[0071] At this point, the method already knows the laser spectrum structure S N (λ i ) and target reflectivity information P N (x, y), and substitute the above information into the compressed sensing reconstruction algorithm to invert the hyperspectral information O(x, y, λ i ).

[0072] In this embodiment, according to the spectral characteristics of different target objects, a compressed sensing algorithm suitable for spectral reconstruction is selected;

[0073] Take the ADMM-TV algorithm as an example:

[0074]

[0075] in, is the estimation result of the target object O; TV(O) is the regularization term of the sparsity constraint of O; α is the penalty parameter for balancing the residual and sparsity in the optimization process; Represents the l2 norm. The above method can obtain the target spectral distribution that is independent of space.

[0076] Therefore, by performing the above calculations for each pixel of the target, a spatial spectral data cube can be obtained. This approach effectively transforms each pixel on the camera into a separate spectrometer, allowing the spatial resolution of imaging to be arbitrarily selected in the experiment.

[0077] Finally, the spectral resolution achievable by the proposed method and the number of spectral channels for hyperspectral imaging are explained in detail.

[0078] By collecting multiple sets of spectral distributions output by the active spectral modulation laser and the reflectivity distribution of the target scene, compressed sensing calculation is performed to reconstruct the spectral distribution of the target object.

[0079] Therefore, the highest achievable spectral resolution is determined by the spectrometer used to acquire the spectrum.

[0080] The actual spectral resolution that can 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 of the method is determined by the wide spectral range output by the active spectral modulation laser and the resolution of the spectrometer for collecting the spectral distribution. The number of spectral channels of the method is an integer of wide spectral range: spectral resolution. According to the spectral resolution and number of spectral channels that can be achieved by the method, it can be determined that the method meets the standard of hyperspectral imaging.

[0082] Embodiment 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, the steps in the hyperspectral imaging method based on active spectral modulation of ultrafast lasers as described in Embodiment 3 are implemented.

[0084] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of hardware embodiments, software embodiments, or embodiments combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage and optical storage, etc.) containing computer-usable program codes.

[0085] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems) and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the process in the flowchart. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0086] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0087] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0088] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiments can be implemented by instructing the relevant hardware through a computer program, and the program can be stored in a computer-readable storage medium, and when the program is executed, it can include the processes in the embodiments of the above-mentioned methods. The storage medium can be a disk, an optical disk, a read-only memory (ROM) or a random access memory (RAM), etc.

[0089] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An active spectrally modulated ultrafast laser, characterized in that: It includes ultrafast pulse laser, preliminary polarization modulation module, nonlinear broadening module and secondary polarization modulation module; The output end of the ultrafast pulse laser is connected to the input end of the preliminary polarization modulation module, the output end of the preliminary polarization modulation module is connected to the input end of the nonlinear broadening module, and the output end of the nonlinear broadening module is connected to 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 the polarization state of each band of laser light by the preliminary modulation module, and then enters the nonlinear broadening module for spectrum broadening to obtain a wide spectrum pulse laser. The wide spectrum pulse laser emitted by the nonlinear broadening module enters the secondary polarization modulation module, randomizes the polarization state of each spectrum, and then irradiates the target scene.

2. An active 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 both include one or a combination of multiple optical polarization modulation devices.

3. An active spectrally modulated ultrafast laser as claimed in claim 1, characterized in that: The nonlinear broadening module adopts nonlinear optical fiber, and the nonlinear optical fiber is selected from nonlinear optical fiber with a wavelength band corresponding to the ultrafast laser seed source.

4. The active spectral modulation ultrafast laser according to claim 1, characterized in that: The ultrafast pulse laser includes pulse lasers in the visible light band, near infrared band, mid-infrared band and terahertz band.

5. A hyperspectral imaging system using an actively spectrally modulated ultrafast laser, characterized in that: It comprises a controller, a camera and the active spectral modulation ultrafast laser according to any one of claims 1 to 4; the preliminary polarization modulation module, the secondary polarization modulation module and the camera are respectively connected to the controller, and the controller comprises a spectral data screening module, a joint acquisition module and a hyperspectral imaging module; The spectral data screening module is configured to: screen and obtain an optimal spectral data set according to 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; 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 spectral data set, and simultaneously acquire reflectivity intensity images of the target scene under different modulation spectra; 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.

6. A hyperspectral imaging system of an actively spectrally modulated ultrafast laser as claimed in claim 5, characterized in that: In the spectral data screening module, the screening basis for the optimal spectral data set is: the several groups of spectral structures with the lowest correlation with other spectral structures calculated based on the cross-correlation algorithm are taken as the optimal spectral data sets.

7. A hyperspectral imaging method using an active spectral modulated ultrafast laser, characterized in that: The steps include: The optimal spectral data set is screened out according to the spectral data outputted by the active spectral modulation ultrafast laser under various modulation parameters of the primary polarization modulation module and the secondary polarization modulation module; Controlling the primary polarization modulation module and the secondary polarization modulation module to switch to corresponding modulation parameters according to the optimal spectral data set, and simultaneously collecting reflectance intensity images of the target scene under different modulation spectra; The reflectance intensity image and the corresponding spectral distribution are combined to obtain a hyperspectral image of the target scene.

8. The hyperspectral imaging method of an active spectral modulation ultrafast laser according to claim 7, characterized in that: When the reflectance intensity image and the corresponding spectral distribution are combined to calculate the hyperspectral image of the target scene, the compressed sensing algorithm is used to invert the spectral distribution of the target scene.

9. The method for hyperspectral imaging of an active spectral modulated ultrafast laser according to claim 7, characterized in that: The reflectivity intensity image of the target scene is: Among them, P N (x, y) is the target reflectivity information, S N (λ i ) is the spectral distribution of the active spectral modulation ultrafast laser after completing a modulation output, O(x, y, λ i ) is the hyperspectral information of the object in the target scene within the modulation spectrum range, N is the Nth spectral structure, λ i is the i-th wavelength channel, x is the horizontal coordinate of the pixel, and y is the vertical coordinate of the pixel.

10. A program product, the program product being a computer program product, comprising a computer program, characterized in that: When the computer program is executed by a processor, the steps in the hyperspectral imaging method of an actively spectrally modulated ultrafast laser as described in any one of claims 7 to 9 are implemented.

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