Hyperspectral Measurement System Based on Multi-channel LED Grating Illumination

Abstract

The present invention discloses a hyperspectral measurement system based on multi-channel LED grating illumination. The light source module is used to generate illumination light with random spectral characteristics based on the illumination light spectral matrix and irradiate a target area, thereby generating reflected light of the target area; the optical sensing module is used to receive the reflected light and perform photoelectric conversion on the reflected light to generate a reflected light spectral measurement matrix, and the spectral calculation module is used to perform hyperspectral calculation of the target area according to the illumination light spectral matrix and the reflected light spectral measurement matrix to obtain a hyperspectral feature matrix, so as to realize hyperspectral measurement of the target area; the light source module is mainly composed of a wide-spectrum LED array, a transmission grating, a perforated baffle, and a focusing lens, which are arranged in parallel and at intervals in sequence along the optical axis. The system of the present invention has a relatively low cost, uses modules with relatively low spectral resolution capabilities, and obtains high-precision spectral characteristics that previously required high-precision devices, and has good practical value.

Description

Technical Field

[0001] The present invention belongs to a hyperspectral measurement system in the field of optical measurement, and particularly relates to a hyperspectral measurement system based on multi-channel LED grating illumination. Background Art

[0002] As an important method for obtaining information, people have put forward higher and higher requirements for the characteristics such as the resolution of optical imaging systems. Limited by the Shannon sampling theorem, high resolution means that the complexity and implementation cost of the imaging system increase non-linearly. In recent years, the compressive sensing theory proposed by Donoho, Candes, Tao and others has proved that under sparse conditions, there is and only one unique solution when solving the ill-conditioned equation in the form of y = Ax. Different from the traditional Shannon sampling theory, this compressive sampling method only needs to utilize the prior sparse information of the original signal and random linear measurements, and can accurately or approximately reconstruct the signal according to the signal measurement values sampled at a sampling frequency far lower than the Nyquist sampling frequency.

[0003] The compressive sensing theory provides an effective solution idea for this demand: introducing the sparsity of the signal, using detection elements with lower sampling accuracy, through a small number of uncorrelated compressive samplings, and realizing high-precision reconstruction of information through a coefficient optimization algorithm. The sparse reconstruction problem is essentially to find as few atoms as possible from the over-complete dictionary Φ (the selected atoms only account for a very small part of all atoms), and approximate the given vector y through their linear combination, that is:

[0004] Find sparset x, s.t. y = Φx

[0005] Definition: For an M×N-dimensional matrix Φ, if its columns have unit length, it is called a dictionary, and the columns of the matrix Φ i are called atoms, where i = 1, 2, 3,..., N.

[0006] Existing hyperspectral imaging technology systems usually need to use scanning or linear array detectors to achieve. Detection systems using compressive sensing often also need to use components such as spectrometers and optical conversion modules, which have high costs, complex designs, and relatively high requirements for the test environment and operation during use. Therefore, it is necessary to design a simpler and lower-cost hyperspectral imaging system. Summary of the Invention

[0007] To solve the problems and meet the requirements in the background art, the present invention discloses a hyperspectral measurement system based on multi-channel LED grating illumination. The present invention uses a wide-spectrum LED array to generate full-spectrum light with a random intensity distribution, irradiates it on a transmission grating placed parallel to the wide-spectrum LED array, and a perforated baffle is placed behind the transmission grating. There is a through hole in the middle of the baffle, allowing only the light in the relatively narrow part in the middle of the grating to pass through, and it is focused on the target area through a focusing lens. The light reflected from the target area is received by a wide-spectrum sensing chip in the light sensing module to obtain the reflected light spectrum detection data corresponding to this intensity distribution. Then, a compressive sensing algorithm is used to calculate the high-precision spectral characteristics of the target area, which has good practical value.

[0008] The technical solution of the present invention is as follows:

[0009] The present invention includes a light source module, a light sensing module, and a spectrum calculation module; the light source module is used to generate illumination light with random spectral characteristics based on the illumination light spectrum matrix and irradiate the target area, thereby generating the reflected light of the target area; the light sensing module is used to receive the reflected light, perform photoelectric conversion on the reflected light, and generate a reflected light spectrum measurement matrix, and the reflected light spectrum measurement matrix is sent to the spectrum calculation module. The spectrum calculation module is used to perform hyperspectral calculation on the target area according to the illumination light spectrum matrix and the reflected light spectrum measurement matrix to obtain a hyperspectral characteristic matrix, realizing hyperspectral measurement of the target area;

[0010] The light source module includes a wide-spectrum LED array, a transmission grating, a perforated baffle, and a focusing lens. The wide-spectrum LED array, the transmission grating, the perforated baffle, and the focusing lens are arranged in parallel and at intervals along the optical axis in sequence. The distance between the perforated baffle and the focusing lens is less than one focal length of the focusing lens. The wide-spectrum LED array generates full-spectrum light with different light intensities, and the full-spectrum light with different light intensities passes through the transmission grating, the perforated baffle, and the focusing lens in sequence to generate illumination light with random spectral characteristics.

[0011] The wide-spectrum LED array includes multiple wide-spectrum LED point light sources and a light source intensity control module. The multiple wide-spectrum LED point light sources are all connected to the light source intensity control module. The multiple wide-spectrum LED point light sources are arranged at intervals in sequence along the direction perpendicular to the optical axis of the light source module, and the light source intensity control module independently controls the brightness of each wide-spectrum LED point light source.

[0012] There are L wide-spectrum LED point light sources set in the wide-spectrum LED array. When the number L of the wide-spectrum LED point light sources is odd, the intervals between the L wide-spectrum LED point light sources are set by the following formula:

[0013]

[0014] When the number L of the wide-spectrum LED point light sources is an even number, the interval between the L wide-spectrum LED point light sources is set by the following formula:

[0015]

[0016] wherein, G k represents the interval between the k-th and the (k + 1)-th wide-spectrum LED point light sources, k represents the serial number of the wide-spectrum LED point light source, k = 1, 2, 3, …, L, and g represents the preset reference interval of the LED point light source.

[0017] The length of the wide-spectrum LED array is not less than (L - 1.5)g; the length of the transmission grating is not less than (L - 1.5)g; the length of the perforated baffle is not less than the length of the transmission grating, wherein, g represents the preset reference interval of the LED point light source; and L represents the number of the wide-spectrum LED point light sources in the wide-spectrum LED array.

[0018] The formula of the irradiation light spectrum matrix C is as follows:

[0019]

[0020] C(i) = [A i (1),..., A i (n),..., A i (q)]

[0021]

[0022] D k (n, i) = lm(k, i) · s k (n, i)

[0023] wherein, C(i) is the spectral data of the i-th irradiation, T represents the occurrence times of the irradiation light, i = 1, 2, 3, …, T, A i (n) is the light intensity of the n-th frequency point in the full-spectrum light source of the i-th irradiation, D k (n, i) is the light intensity of the k-th wide-spectrum LED point light source at the n-th frequency point during the i-th irradiation, L represents the number of the wide-spectrum LED point light sources in the wide-spectrum LED array, k = 1, 2, 3, …, L; q represents the number of sampling frequency points of the full-spectrum light source in the irradiation light spectrum matrix C, n = 1, 2, 3, …, q, lm(k, i) is the light intensity of the k-th wide-spectrum LED point light source during the i-th irradiation, and s k (n, i) represents the emission coefficient of the k-th wide-spectrum LED point light source at the n-th frequency point. If the light energy of the k-th wide-spectrum LED point light source at the n-th frequency point exits from the perforated baffle, the emission coefficient is 1, otherwise it is 0.

[0024] The illumination light spectrum matrix C satisfies the following conditions:

[0025]

[0026] where ε is a constraint coefficient, which is a constant, ε ∈ (0, 1); Θ is a sensing matrix, satisfying Θ = CΨ; Ψ is a standard orthogonal basis matrix of size q×q: Ψ = [Ψ1…Ψ n …Ψ q , Ψ n is a column vector of length q, representing the mapping basis vector; a is a coefficient matrix of size q×1, a = [a1 a2…a q T , satisfying X = Ψa.

[0027] The illumination light spectrum matrix C is a random Gaussian matrix, a random Bernoulli matrix, a Toeplitz matrix, etc.

[0028] The optical sensing module is mainly composed of a wide-spectrum sensing chip. The wide-spectrum sensing chip performs photoelectric conversion on the reflected light to obtain the spectral information of the reflected light, and then generates a reflected light spectrum measurement matrix based on the spectral information of the reflected light. The formula for the reflected light spectrum measurement matrix M is as follows:

[0029]

[0030] M(i) = [B i (1)…B i (m)…B i (p)]

[0031] where M(i) is the reflected light spectrum data measured after the i-th irradiation, i = 1, 2, 3, … T, and T represents the number of occurrences of the illumination light; B i (m) is the light intensity at the m-th frequency point in the reflected light spectrum data measured after the i-th irradiation, m = 1, 2, 3, … p, and p is the number of sampling frequency points of the wide-spectrum sensing chip.

[0032] The following formula is satisfied among the illumination light spectrum matrix, the reflected light spectrum measurement matrix, and the hyperspectral feature matrix:

[0033] M = CX

[0034] X = [X(1)…X(n)…X(q)]

[0035] where X(n) is the reflectivity of the target area at the n-th frequency point, n = 1, 2, 3, … q, and q represents the number of sampling frequency points of the full-spectrum light source in the illumination light spectrum matrix C.

[0036] Compared with the prior art, the present invention can achieve the following beneficial effects: ​

[0037] The present invention generates irradiation light with randomness multiple times through a wide-spectrum LED array. By setting the spectral distribution of the irradiation light, appropriate sparse sampling data is formed, and spectral data reflected by a target area is obtained from a wide-spectrum optical sensing module with a low sampling accuracy. Finally, a calculation module is used to solve the high-precision spectral characteristics of the target area by adopting a compressive sensing algorithm.

[0038] The present invention is constructed by using low-cost components, without a coating and filtering structure with complex processes. High-precision results can also be obtained through calibration in the presence of processing and manufacturing errors. Both the light source module and the optical sensing module have broadband characteristics. By using a module with a low spectral resolution ability, high-precision spectral characteristics that previously required high-precision devices can be obtained. The system has a low cost, simple operation, and has application potential in a series of scenarios such as agricultural product detection and water quality detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 is a schematic diagram of the overall structure of the present invention;

[0040] Figure 2 is a schematic diagram of the structure of the light source module (1) of the present invention;

[0041] Figure 3 is a schematic diagram of the structure of the wide-spectrum LED array (11) of the present invention; wherein Figure 3 (A) is a schematic diagram of the structure of the wide-spectrum LED array (11) when the number of wide-spectrum LED point light sources (111) is odd; Figure 3 (B) is a schematic diagram of the structure of the wide-spectrum LED array (11) when the number of wide-spectrum LED point light sources (111) is even;

[0042] Figure 4 is a schematic diagram of the irradiation light with random spectral characteristics generated by the light source module (1) of the present invention; wherein Figure 4 (A) is a schematic diagram of the emitted light of the wide-spectrum LED point light source (111) being frequency-selected; Figure 4 (B) is a schematic diagram of the optical path of a certain frequency light in the emitted light of the wide-spectrum LED point light source (111);

[0043] Figure 5 is a schematic diagram of the optical sensing module (2);

[0044] In the figure: light source module 1, wide-spectrum LED array 11, transmission grating 12, perforated baffle 13, through hole 131, focusing lens 14, optical sensing module 2, wide-spectrum sensing chip 21, peripheral circuit 22, spectral calculation module 3. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0045] To make the present invention more obvious and understandable, preferred embodiments will be described in detail below in conjunction with the accompanying drawings.

[0046] As Figure 1 and Figure 2 shown, the hyperspectral measurement system includes a light source module 1, a light sensing module 2, and a spectral calculation module 3; hyperspectrum specifically uses the prior sparse information of the original signal and random linear measurements to accurately or approximately reconstruct the signal according to the signal measurement values sampled at a much lower frequency than the Nyquist sampling frequency.

[0047] The light source module 1 is used to generate illumination light with random spectral characteristics based on the illumination light spectral matrix and irradiate the target area, where the spectral information of the illumination light is the illumination light spectral matrix, thereby generating the reflected light of the target area; the light sensing module 2 is used to receive the reflected light and generate a reflected light spectral measurement matrix after photoelectric conversion of the reflected light, and the reflected light spectral measurement matrix is sent to the spectral calculation module 3. The spectral calculation module 3 is used to perform hyperspectral calculation of the target area using the compressive sensing algorithm according to the illumination light spectral matrix and the reflected light spectral measurement matrix to obtain a hyperspectral feature matrix, and realize hyperspectral measurement of the target area;

[0048] The light source module 1 includes a wide-spectrum LED array 11, a transmission grating 12, a perforated baffle 13, and a focusing lens 14. The wide-spectrum LED array is specifically composed of multiple wide-spectrum LED point light sources 111. The emission frequency band of each wide-spectrum LED point light source completely covers the visible light frequency band. The wide-spectrum LED array 11, the transmission grating 12, the perforated baffle 13, and the focusing lens 14 are arranged in parallel and at intervals along the optical axis in sequence. There are no restrictive conditions for the intervals among the wide-spectrum LED array 11, the transmission grating 12, and the perforated baffle 13. Due to the dispersion effect of the transmission grating 13, after the full-spectrum light emitted by the wide-spectrum LED point light source 111 passes through the transmission grating 13, lights of different frequencies will have different emission angles. Currently, only the light with an emission angle within a certain range from the wide-spectrum LED point light source 111 can emerge from the perforated baffle 13. The distance between the perforated baffle 13 and the focusing lens 14 is less than the focal length of the focusing lens 14. A slit 131 is opened in the middle of the perforated baffle 13. The center of the slit 131 and the center of the wide-spectrum LED array 11 are on the optical axis of the light source module 1. The width of the slit 131 in the y direction is less than or equal to g / 2. In specific implementation, the slit width is as small as possible, allowing only the light in the relatively narrow middle part to pass through. After being selected by the perforated baffle 13, the emitted light forms an emission light with a random spectral characteristic. The emission light then converges on the target area through the focusing lens 14. The wide-spectrum LED array 11 is used to generate full-spectrum lights with different light intensities multiple times according to the illumination light spectral matrix. The light intensities are randomly distributed. The full-spectrum lights with different light intensities pass through the transmission grating 12, the perforated baffle 13, and the focusing lens 14 in sequence to generate an illumination light with a random spectral characteristic. The illumination light is full-spectrum light. The brightness of each wide-spectrum LED point light source 111 correspondingly affects the light intensity of a spectral interval in the illumination light.

[0049] The wide-spectrum LED array 11 includes multiple identical wide-spectrum LED point light sources 111 and a light source intensity control module 112. The multiple wide-spectrum LED point light sources 111 are all connected to the light source intensity control module 112. The multiple wide-spectrum LED point light sources 111 are arranged at intervals in sequence along the direction perpendicular to the optical axis of the light source module 1. The light source intensity control module 112 independently controls the brightness of each wide-spectrum LED point light source 111 according to the illumination light spectral matrix.

[0050] In this embodiment, the distance between the wide-spectrum LED array (11) and the transmission grating (12) is 10 cm, the distance between the transmission grating (12) and the perforated baffle (13) is 7 cm, and the distance between the perforated baffle (13) and the focusing lens (14) is 1 cm. The wide-spectrum LED array (11) includes 16 identical wide-spectrum LED point light sources (111) and a light source intensity control module (112). The model of the wide-spectrum LED point light source (111) is EAHC2835WD0, which covers a wavelength range from 400 nm to 800 nm. The light source intensity control module (112) adjusts the luminous intensity by adjusting the supply voltage of the wide-spectrum LED point light source (111), and the range of the supply voltage is between 2.5V and 3.3V.

[0051] In this embodiment, the length of the wide-spectrum LED array (11) in the y-axis direction is 10 cm, and the width in the z-axis direction is 1 cm. The length of the transmission grating (12) in the y-axis direction is 15 cm, and the width in the z-axis direction is 8 cm. The perforated baffle (13) is made of opaque acrylic material, with a length of 15 cm in the y-axis direction and a width of 8 cm in the z-axis direction. The position of the opening is aligned with the center of the wide-spectrum LED array (11), and the size of the opening is as small as possible. The opening is a slit with a length of 0.3 cm in the y-axis direction and a length of 3 cm in the z-axis direction.

[0052] There are L wide-spectrum LED point light sources 111 provided in the wide-spectrum LED array 11. As Figure 3 shown in (A) and (B) of

[0053]

[0054] When the number L of the wide-spectrum LED point light sources 111 is even, the interval between the L wide-spectrum LED point light sources 111 is set by the following formula:

[0055]

[0056] where G k represents the interval between the kth and the (k + 1)th wide-spectrum LED point light sources 111, k represents the serial number of the wide-spectrum LED point light source 111, k = 1, 2, 3,..., L, and g represents the preset reference interval of the LED point light source.

[0057] In this embodiment, L is 16, g is 0.8 cm, the interval between the 8th and 9th wide-spectrum LED point light sources (111) is 0.4 cm, and the intervals between the remaining wide-spectrum LED point light sources (111) are all 0.8 cm.

[0058] The length of the wide-spectrum LED array 11 is not less than (L - 1.5)g; the length of the transmission grating 13 is not less than (L - 1.5)g; the length of the perforated baffle 13 is not less than the length of the transmission grating 13, where g represents the preset reference interval of the LED point light source; L represents the number of wide-spectrum LED point light sources 111 in the wide-spectrum LED array 11.

[0059] As Figure 4 shown in (A) and (B) of

[0060]

[0061] C(i) = [A i (1),..., A i (n),..., A i (q)]

[0062]

[0063] D k (n, i) = lm(k, i) · s k (n, i)

[0064] where C(i) is the spectral data of the i-th irradiation, T represents the number of occurrences of the irradiation light, i = 1, 2, 3,..., T, A i (n) is the light intensity of the n-th frequency point in the full-spectrum light source of the i-th irradiation, D k (n, i) is the light intensity of the k-th wide-spectrum LED point light source 111 at the n-th frequency point during the i-th irradiation, L represents the number of wide-spectrum LED point light sources 111 in the wide-spectrum LED array 11, k = 1, 2, 3,..., L; q represents the number of sampling frequency points of the full-spectrum light source in the irradiation light spectral matrix C, n = 1, 2, 3,..., q, lm(k, i) is the light intensity of the k-th wide-spectrum LED point light source 111 during the i-th irradiation, s k (n, i) represents the emission coefficient of the k-th wide-spectrum LED point light source 111 at the n-th frequency point. If the light energy of the k-th wide-spectrum LED point light source 111 at the n-th frequency point exits from the perforated baffle 13, the emission coefficient is 1, otherwise it is 0; specifically: when the light energy of the k-th wide-spectrum LED point light source 111 at the n-th frequency point exits from the perforated baffle 13, a coordinate system is established for the light source module 1. The position of the lowermost wide-spectrum LED point light source 111 in the wide-spectrum LED array 11 is used as the origin of the coordinate system, the height direction of the wide-spectrum LED array 11 is used as the y-axis, the direction parallel to the optical axis is used as the x-axis, and the direction perpendicular to the x-axis and y-axis is used as the z-axis. The frequency f k (n) of the k-th wide-spectrum LED point light source 111 at the n-th frequency point satisfies the following formula y2 represents the y-axis coordinate value of the light of the nth frequency point of the kth wide-spectrum LED point light source 111 passing through the transmission grating 12. c0 is the propagation speed of electromagnetic waves in vacuum, and its value is 3×10 8 m / s; y1 represents the y-axis coordinate value of the kth wide-spectrum LED point light source 111. d is the grating constant of the transmission grating 12. W1 is the interval between the wide-spectrum LED array 11 and the transmission grating 12. W2 is the interval between the transmission grating 12 and the perforated baffle 13. In this embodiment, W1 is 10 cm and W2 is 7 cm. g represents the preset reference interval of the LED point light source. sina represents the incident angle when the light of the nth frequency point of the kth wide-spectrum LED point light source 111 enters the transmission grating 12, and sinβ represents the exit angle when the light of the nth frequency point of the kth wide-spectrum LED point light source 111 exits the transmission grating 12. Specifically, in the implementation, the frequency range of the full-spectrum light of the wide-spectrum LED array 11 is f min ~f max , and the number of sampled frequency points is q.

[0065] In this embodiment, the occurrence times T of the full-spectrum light is 16, and the frequency range of the full-spectrum light is 3.75×10^14Hz~7.5×10^14Hz. The hyperspectral detector continuously calibrates the irradiated light. The model of the hyperspectral detector is AFX17, the spectral sampling accuracy is 3.5 nanometers, the number of sampling frequency points q is 114, the high-precision spectral data of the irradiated light is obtained, the required irradiated light is obtained, and the high-precision spectral data of the irradiated light is stored as the irradiated light spectral matrix.

[0066] The irradiated light spectral matrix C satisfies the following conditions:

[0067]

[0068] Among them, ε is the constraint coefficient, which is a constant, ε∈(0,1); Θ is the sensing matrix, satisfying Θ = CΨ; Ψ is a standard orthogonal basis matrix of size q×q: Ψ = [Ψ1…Ψ n …Ψ q , Ψ n is a column vector of length q, representing the mapping basis vector; a is a coefficient matrix of size q×1, a = [a1 a2…a q T , satisfying X = Ψa.

[0069] The irradiated light spectral matrix C is a random Gaussian matrix, a random Bernoulli matrix, a Toeplitz matrix, etc.

[0070] Such as Figure 5 ​As shown, the optical sensing module 2 is mainly composed of a wide-spectrum sensing chip 21 and its peripheral circuit 22. The measurement frequency range of the wide-spectrum sensing chip 21 completely covers the frequency range f of the full-spectrum light min ~f max . The number of sampling frequency points of the wide-spectrum sensing chip 21 within f min ~f max is p. The spectral sampling accuracy of the wide-spectrum sensing chip 21 is less than that of the hyperspectral detector, that is, p < q. In this embodiment, the model of the wide-spectrum sensing chip (21) is c12880ma, the measured spectral wavelength range is from 340nm to 850nm, the frequency range is 3.5×10^14Hz~8.8×10^14Hz, the number of sampling frequency points p is 33, and the spectral resolution of the wide-spectrum sensing chip (21) is 12nm. After the wide-spectrum sensing chip 21 performs photoelectric conversion on the reflected light, it obtains the spectral information of the reflected light and generates a reflected light spectral measurement matrix. The formula of the reflected light spectral measurement matrix M is as follows:

[0071]

[0072] M(i) = [B i (1)…B i (m)…B i (p)]

[0073] Among them, M(i) is the spectral data of the reflected light measured after the i-th irradiation, i = 1, 2, 3, … T, and T represents the number of occurrences of the irradiation light; B i (m) is the light intensity of the m-th frequency point in the spectral data of the reflected light measured after the i-th irradiation, m = 1, 2, 3, … p, and p is the number of sampling frequency points of the wide-spectrum sensing chip (21).

[0074] The following formula is satisfied among the irradiation light spectral matrix, the reflected light spectral measurement matrix, and the hyperspectral feature matrix:

[0075] M = CX

[0076] X = [X(1)…X(n)…X(q)]

[0077] Among them, X(n) is the reflectivity of the target area at the n-th frequency point, n = 1, 2, 3, … q, and q represents the number of sampling frequency points of the full-spectrum light source in the irradiation light spectral matrix C.

[0078] The accuracy of the spectral features in the hyperspectral feature matrix is higher than the spectral sampling accuracy of the wide-spectrum sensing chip 21 in the optical sensing module 2 (that is, the accuracy of the spectral features in the reflected light spectral measurement matrix), realizing hyperspectral measurement.

[0079] As described above, the present invention realizes a hyperspectral measurement system based on multi-channel LED grating illumination. By utilizing the optical dispersion effect of the grating structure and the selection effect of the baffle with through holes, by adjusting the brightness of each point light source in the broadband LED array, an illumination light with a randomly set frequency distribution is set, spectral data reflected from the target area is obtained from the optical sensing module, and finally, the high-precision spectral characteristics of the target area are calculated by the calculation module using the compressive sensing algorithm.

[0080] As described above, the above are only preferred examples of the present invention and do not limit the present invention in any form. Any person skilled in the art may use the technical content disclosed above to make changes or modifications into equivalent examples with equivalent changes. However, as long as it does not depart from the content of the technical solution of the present invention, any simple modification, equivalent change, and modification made to the above examples based on the technical essence of the present invention still fall within the protection scope of the present invention.

Claims

1. A hyperspectral measurement system based on multi-channel LED grating illumination, characterized in that, It includes a light source module (1), a light sensing module (2) and a spectral calculation module (3); the light source module (1) is used to generate illuminating light with random spectral characteristics based on the illuminating light spectral matrix and irradiate the target area, so as to generate the reflected light of the target area; The light sensing module (2) is used to receive the reflected light, perform photoelectric conversion on the reflected light and generate a reflected light spectral measurement matrix, and the reflected light spectral measurement matrix is sent to the spectral calculation module (3). The spectral calculation module (3) is used to perform hyperspectral calculation on the target area according to the illuminating light spectral matrix and the reflected light spectral measurement matrix to obtain a hyperspectral feature matrix, so as to realize hyperspectral measurement of the target area; The light source module (1) includes a wide-spectrum LED array (11), a transmission grating (12), a perforated baffle (13) and a focusing lens (14). The wide-spectrum LED array (11), the transmission grating (12), the perforated baffle (13) and the focusing lens (14) are arranged in parallel and at intervals along the optical axis in sequence. The distance between the perforated baffle (13) and the focusing lens (14) is less than one focal length of the focusing lens (14). The wide-spectrum LED array (11) generates full-spectrum light with different light intensities, and the full-spectrum light with different light intensities passes through the transmission grating (12), the perforated baffle (13) and the focusing lens (14) in sequence to generate illuminating light with random spectral characteristics; The formula of the illuminating light spectral matrix C is as follows: C(i) = [A i (1),..., A i (n),..., A i (q)] D k (n,i) = lm(k,i)·s k (n,i) Among them, C(i) is the spectral data of the i-th irradiation, T represents the number of occurrences of the irradiation light, i = 1, 2, 3, …, T, A i (n) is the light intensity of the n-th frequency point in the full-spectrum light source of the i-th irradiation, D k (n, i) is the light intensity of the k-th wide-spectrum LED point light source (111) at the n-th frequency point during the i-th irradiation, L represents the number of wide-spectrum LED point light sources (111) in the wide-spectrum LED array (11), k = 1, 2, 3, …, L; q represents the number of sampling frequency points of the full-spectrum light source in the irradiation light spectral matrix C, n = 1, 2, 3, …, q, lm(k, i) is the light intensity of the k-th wide-spectrum LED point light source (111) during the i-th irradiation, s k (n, i) represents the exit coefficient of the k-th wide-spectrum LED point light source (111) at the n-th frequency point. If the light energy of the k-th wide-spectrum LED point light source (111) at the n-th frequency point exits from the perforated baffle (13), the exit coefficient is 1, otherwise it is 0.

2. The hyperspectral measurement system based on multi-channel LED grating illumination according to claim 1, wherein The wide-spectrum LED array (11) includes a plurality of wide-spectrum LED point light sources (111) and a light source intensity control module (112). The plurality of wide-spectrum LED point light sources (111) are all connected to the light source intensity control module (112). The plurality of wide-spectrum LED point light sources (111) are arranged at intervals in sequence along the direction perpendicular to the optical axis of the light source module (1), and the light source intensity control module (112) independently controls the brightness of each wide-spectrum LED point light source (111).

3. The hyperspectral measurement system based on multi-channel LED grating illumination according to claim 1, wherein There are L wide-spectrum LED point light sources (111) arranged in the wide-spectrum LED array (11). When the number L of the wide-spectrum LED point light sources (111) is odd, the interval between the L wide-spectrum LED point light sources (111) is set by the following formula: When the number L of the wide-spectrum LED point light sources (111) is even, the interval between the L wide-spectrum LED point light sources (111) is set by the following formula: Among them, G k represents the interval between the k-th and the (k + 1)-th wide-spectrum LED point light source (111), k represents the serial number of the wide-spectrum LED point light source (111), k = 1, 2, 3, …, L, and g represents the preset reference interval of the LED point light source.

4. A hyperspectral measurement system based on multi-channel LED grating illumination according to claim 1, characterized in that, The length of the wide-spectrum LED array (11) is not less than (L×1.5)g; the length of the transmission grating (12) is not less than (L×1.5)g; the length of the perforated baffle (13) is not less than the length of the transmission grating (12), where g represents the preset reference interval of the LED point light source; L represents the number of wide-spectrum LED point light sources (111) in the wide-spectrum LED array (11).

5. The hyperspectral measurement system based on multi-channel LED grating illumination according to claim 1, wherein The illuminating light spectral matrix C satisfies the following conditions: where ε is the constraint coefficient, which is a constant and ε ∈ (0, 1); Θ is the sensing matrix, satisfying Θ = CΨ; Ψ is an orthonormal basis matrix of size q × q: Ψ = [Ψ1 … Ψ n … Ψ q , Ψ n is a column vector of length q, representing the mapping basis vector; a is a coefficient matrix of size q × 1, a = [a1 a2 … a q T , satisfying X = Ψa.​ 6. The hyperspectral measurement system based on multi-channel LED grating illumination according to claim 1, characterized in that, The illuminating light spectral matrix C is a random Gaussian matrix, a random Bernoulli matrix, a Toeplitz matrix, etc.

7. A hyperspectral measurement system based on multi-channel LED grating illumination according to claim 1, characterized in that The light sensing module (2) is mainly composed of a wide-spectrum sensing chip (21). The wide-spectrum sensing chip (21) performs photoelectric conversion on the reflected light to obtain the spectral information of the reflected light, and then generates a reflected light spectral measurement matrix based on the spectral information of the reflected light. The formula for the reflected light spectral measurement matrix M is as follows: M(i) = B i (1) … B i (m) … B i (p) Among them, M(i) is the reflected light spectrum data measured after the i-th irradiation, where i = 1, 2, 3, … T, and T represents the number of occurrences of the irradiation light; B i (m) is the light intensity at the m-th frequency point in the reflected light spectrum data measured after the i-th irradiation, where m = 1, 2, 3, … p, and p is the number of sampling frequency points of the broadband spectral sensing chip (21).

8. A hyperspectral measurement system based on multi-channel LED grating illumination according to claim 1, characterized in that, The following formula is satisfied among the illumination light spectral matrix, the reflected light spectral measurement matrix, and the hyperspectral feature matrix: M = CX X = X(1) … X(n) … X(q) Where X(n) is the reflectivity of the target area at the nth frequency point, n = 1, 2, 3,... q, and q represents the sampling frequency points of the full-spectrum light source in the illumination light spectral matrix C.

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