Hyperspectral system based on laser

Abstract

The utility model discloses a hyperspectral system based on laser, and aims to improve the uniformity and accuracy of hyperspectral imaging. The system comprises a light source array, a reflector, a light guide pipe, two lenses, a camera, a PC, a microprocessor and a stepping motor. Laser light sources in the light source array are distributed on a virtual circumference, and the reflector is controlled to rotate through the stepping motor, so that uniform distribution of laser spots is realized. The system further comprises a frosted mirror and a vibration device so as to eliminate laser speckles, and the light beam is adjusted through the lens so as to obtain a needed light spot area. The system can effectively improve the defects in the prior art and improve the hyperspectral imaging quality.

Description

Technical Field

[0001] The utility model relates to a laser-based hyperspectral system, belonging to the technical field of hyperspectral imaging. Background Art

[0002] Laser hyperspectral imaging systems in the prior art, such as the Chinese patent No. 2023232205512, refer to Figure 1 By using multiple lasers of different colors to generate lasers of different wavelengths, and utilizing the characteristic that the incident direction of the laser and the incident direction of the beam expander converge at the rotating axis of the reflector, it is possible to selectively reflect laser lights of different colors to the beam expander by rotating the reflector at different angles without changing the direction of the light reflected by the reflector to the beam expander. The beam expander can evenly diffuse the light into a larger spot, which can be used to illuminate objects and achieve hyperspectral imaging.

[0003] However, the problem with the above patents is that the lasers are arranged in a straight line, the mirror angle and the laser spacing are in a nonlinear trigonometric function relationship, and the calculation of the mirror angle adjustment is relatively complicated.

[0004] In addition, another problem with the above patent is that a beam expander is used to diffuse the laser into a larger spot, but the uniformity is still not good enough, and it is not suitable for scenarios with high requirements for hyperspectral imaging. Summary of the Invention

[0005] The technical problem to be solved by the utility model is to provide a laser-based hyperspectral system to overcome the deficiencies of the prior art.

[0006] The technical solution of the utility model is:

[0007] A laser-based hyperspectral system, comprising a light source array, a reflector, a light pipe, a first lens, a second lens, a camera, a PC, a microprocessor, and a stepper motor;

[0008] The light source array includes one or more laser light sources, each laser light source has a different wavelength, the laser light sources of the light source array are arranged on the circumference of a virtual circle, the irradiation direction of the laser light source of each light source array points to the center point of the virtual circle, and the microprocessor is electrically connected to the light source array;

[0009] The rotating shaft of the stepper motor passes through the center point of the virtual circle and is perpendicular to the plane where the virtual circle is located. The reflector is fixed on the rotating shaft of the stepper motor, the reflector is parallel to the rotating shaft of the stepper motor, and the reflective surface of the reflector faces the side where the light source array is located. The PC is electrically connected to the microprocessor;

[0010] The light guide entrance is located behind the light output of the reflector, a first lens is provided at the light guide exit, and a second lens is provided behind the first lens;

[0011] The second lens is arranged at a beam waist position behind the first lens;

[0012] The field of view of the camera is within the range of the output light field of the second lens, and the camera is electrically connected to the PC;

[0013] The PC is electrically connected to the microprocessor.

[0014] Furthermore, it also includes a frosted mirror and a vibration device, the frosted mirror is fixedly connected to the vibration device, and the frosted mirror is arranged between the light guide tube and the focus of the first lens.

[0015] Furthermore, the laser light sources of the light source array are distributed at equal intervals, and the step angle at which the stepping motor drives the reflector to rotate is half of the angular interval between adjacent laser light sources.

[0016] The beneficial effects of the present invention are: compared with the prior art,

[0017] 1) The present invention arranges the laser light sources of the light source array on the circumference of a virtual circle, with the illumination direction of the laser light source of each light source array pointing to the center point of the virtual circle. Then, the rotating shaft of the stepper motor passes through the center point of the virtual circle, so that the rotation angle of the reflector and the angular spacing of the laser light sources are linearly related. Compared with the nonlinear trigonometric function relationship, the reflector angle adjustment calculation of the present patent is relatively simple and consumes less computing resources of the processor.

[0018] 2) The utility model is connected to the frosted mirror via a vibration device. When the laser passes through the frosted mirror, the vibration device vibrates, which can eliminate the laser speckle sent by the light guide;

[0019] 3) The present invention receives light reflected from the reflector through a light guide, which can, firstly, change the propagation direction of the light source, making the overall arrangement of the device easier, and secondly, convert the laser light spots of different modes sent by the laser light source into Gaussian distribution spots;

[0020] 4) The utility model arranges the second lens at the beam waist position behind the first lens, which firstly makes the Gaussian distribution of the light spot more uniform, and secondly expands the light spot emitted by the light guide;

[0021] 5) The present invention arranges the laser light sources of the light source array at equal intervals, so that the angle of each step of the reflector rotation is equal, making it easier to adjust and control the rotation angle of the reflector. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1A schematic diagram of the structure of the background technology of the present utility model;

[0023] Figure 2 It is a structural diagram of the utility model;

[0024] Figure 3 This is a schematic diagram of the circuit structure of the utility model;

[0025] Figure 4 The left side shows the 895 modal light spot, and the right side shows the result obtained after the light spot passes through this system;

[0026] Figure 5 The left side shows the 880 modal light spot, and the right side shows the result obtained after the light spot passes through this system;

[0027] Figure 6 The left side shows the 850 modal light spot, and the right side shows the result obtained after the light spot passes through this system;

[0028] Figure 7 The left side shows the 830 modal light spot, and the right side shows the result obtained after the light spot passes through this system;

[0029] Figure 8 The left side shows the 820 modal light spot, and the right side shows the result obtained after the light spot passes through this system;

[0030] Figure 9 The left side shows the 815 modal light spot, and the right side shows the result obtained after the light spot passes through this system;

[0031] Figure 10 The left side shows the 808 modal light spot, and the right side shows the result obtained after the light spot passes through this system;

[0032] Figure 11 The left side shows the 780 modal light spot, and the right side shows the result obtained after the light spot passes through this system;

[0033] Figure 12 The left side shows the 690 modal light spot, and the right side shows the result obtained after the light spot passes through this system;

[0034] Figure 13 The left side shows the 660 modal light spot, and the right side shows the result obtained after the light spot passes through this system;

[0035] Figure 14 The left side shows the 650 modal light spot, and the right side shows the result obtained after the light spot passes through this system;

[0036] Figure 15 The left side shows the 635 modal light spot, and the right side shows the result obtained after the light spot passes through this system;

[0037] Figure 16The left side shows the 555 modal light spot, and the right side shows the result obtained after the light spot passes through this system;

[0038] Figure 17 The left side shows the 532 modal light spot, and the right side shows the result obtained after the light spot passes through this system;

[0039] Figure 18 The left side shows the 520 modal light spot, and the right side shows the result obtained after the light spot passes through this system;

[0040] Figure 19 The left side shows the 488 modal light spot, and the right side shows the result obtained after the light spot passes through this system. DETAILED DESCRIPTION

[0041] In order to better understand the above technical solution, the above technical solution will be described in detail below with reference to the accompanying drawings and specific implementation methods.

[0042] Implementation Example 1: Reference Figure 2-3 , a laser-based hyperspectral system, the system comprising a light source array 1, a reflector 2, a light pipe 4, a first lens 7, a second lens 8, a camera 10, a PC 11, a microprocessor 12 and a stepper motor 3;

[0043] The light source array 1 includes more than one laser light source, each laser light source has a different wavelength, the laser light sources of the light source array 1 are arranged on the circumference of a virtual circle, and the irradiation direction of the laser light source of each light source array 1 points to the center point of the virtual circle. The microprocessor 12 is electrically connected to the light source array 1; the virtual circle here is an imaginary circle and does not have a physical structure. It is only used to assist in the arrangement of the laser light source and the stepper motor 3 position.

[0044] The rotating shaft of the stepper motor 3 passes through the center point of the virtual circle and is perpendicular to the plane where the virtual circle is located. The reflector 2 is fixed on the rotating shaft of the stepper motor 3. The reflector 2 is parallel to the rotating shaft of the stepper motor 3. The reflective surface of the reflector 2 faces the side where the light source array 1 is located. The PC 11 is electrically connected to the microprocessor 12.

[0045] The incident port of the light guide 4 is located behind the outgoing light of the reflector 2. A first lens 7 is provided at the outlet of the light guide 4. A second lens 8 is provided behind the first lens 7.

[0046] The second lens 8 is arranged at the beam waist position behind the first lens 7;

[0047] The field of view of the camera 10 is within the range of the output light field of the second lens 8, and the camera 10 is electrically connected to the PC 11;

[0048] The PC 11 is electrically connected to the microprocessor 12 .

[0049] Furthermore, it also includes a frosted mirror 5 and a vibration device 6 , wherein the frosted mirror 5 is fixedly connected to the vibration device 6 , and the frosted mirror 5 is arranged between the light guide 4 and the focus of the first lens 7 .

[0050] Furthermore, the laser light sources of the light source array 1 are distributed at equal intervals, and the stepping angle at which the stepping motor 3 drives the reflector 2 to rotate is half of the angular interval between adjacent laser light sources.

[0051] We use a specific optical configuration to control the propagation and distribution of laser light to achieve a uniform beam spot. Specifically, 20 lasers of different wavelengths are arranged in a quarter-circle arc. Computer-controlled reflectors at the arc's neutral point sequentially and regularly direct the laser light into a 10-cm-long light pipe. The laser light undergoes multiple reflections and mode mixing within the light pipe. Despite the complex optical path resulting from these reflections and mode mixing, the light intensity distribution at the exit surface remains Gaussian.

[0052] According to the propagation characteristics of Gaussian beams (1), when the target beam width W(z) is larger, the light spot we obtain is larger and the Gaussian beam is flatter. The formula for the transverse intensity distribution of a Gaussian beam is:

[0053]

[0054] The formula for the change of the beam width w(z) of a Gaussian beam with the propagation distance z is:

[0055]

[0056] z_R is the Rayleigh length, defined as:

[0057]

[0058] Where I(r,z) is the intensity at a distance r from the beam center and a propagation distance z. I0 is the peak intensity. ω0 is the beam waist radius at the focus (or narrowest point). w(z) is the beam width at a distance z from the focus. r is the lateral distance from the beam center. λ is the wavelength of the light.

[0059] In order to obtain a larger spot size within a limited distance, we need a larger initial beam waist radius ω0. We use the magnification M to express the lens equation of the Gaussian beam:

[0060] w′0=Mw0 (4)

[0061] M is the magnification, given by:

[0062]

[0063] r is a dimensionless parameter given by the following formula:

[0064]

[0065] Where ω′0 is the new beam waist radius after the lens. r is the initial magnification. z0 is the waist position in front of the lens. f is the focal length of the lens.

[0066] The calculation formula for the new waist position z′0 is:

[0067]

[0068] The new calculation formula for waist width ω′0 is:

[0069]

[0070] Where z′0 is the new waist position after the lens. z0 is the waist position in front of the lens. f is the focal length of the lens. ω′0 is the new waist radius after the lens. ω0 is the waist radius in front of the lens. z0 is the waist position in front of the lens.

[0071] Therefore, a convex lens with a focal length of 5 cm is placed 6 cm from the light pipe exit to increase the initial beam waist radius ω0. A second lens is placed behind the initial beam waist to further adjust the beam to obtain the desired target spot area. This configuration, leveraging the propagation characteristics of Gaussian beams and the lens equation, effectively controls the beam distribution within a limited distance, resulting in a large, uniform spot.

[0072] The effects of different modes of light spots passing through this system are as follows: Figure 4-Figure 19 As shown in FIG, the experimental results show that after the laser spots of different modes pass through the system, the obtained spots have good uniformity and are circular.

[0073] The above content is a further detailed description of the present invention in conjunction with specific preferred embodiments, and the specific implementation of the present invention cannot be considered to be limited to these descriptions. For those skilled in the art of the present invention, without departing from the concept of the present invention, several simple deductions or substitutions can be made, which should be considered to fall within the scope of protection of the present invention.

Claims

1. A laser-based hyperspectral system, characterized in that: The system comprises a light source array (1), a reflector (2), a light pipe (4), a first lens (7), a second lens (8), a camera (10), a PC (11), a microprocessor (12) and a stepping motor (3); The light source array (1) includes one or more laser light sources, each laser light source has a different wavelength, the laser light sources of the light source array (1) are arranged on the circumference of a virtual circle, the irradiation direction of the laser light source of each light source array (1) points to the center point of the virtual circle, and the microprocessor (12) is electrically connected to the light source array (1); The rotating shaft of the stepping motor (3) passes through the center point of the virtual circle and is perpendicular to the plane where the virtual circle is located. The reflector (2) is fixed on the rotating shaft of the stepping motor (3). The reflector (2) is parallel to the rotating shaft of the stepping motor (3). The reflecting surface of the reflector (2) faces the side where the light source array (1) is located. The PC (11) is electrically connected to the microprocessor (12). The light guide tube (4) has an incident port located behind the light output from the reflector (2); a first lens (7) is provided at the light guide tube (4) outlet, and a second lens (8) is provided behind the first lens (7); The second lens (8) is arranged at a beam waist position behind the first lens (7); The field of view of the camera (10) is located within the range of the output light field of the second lens (8), and the camera (10) is electrically connected to the PC (11); The PC (11) is electrically connected to the microprocessor (12).

2. The laser-based hyperspectral system according to claim 1, characterized in that It also includes a frosted mirror (5) and a vibration device (6), wherein the frosted mirror (5) is fixedly connected to the vibration device (6), and the frosted mirror (5) is arranged between the light guide (4) and the focus of the first lens (7).

3. The laser-based hyperspectral system according to claim 1, characterized in that The laser light sources of the light source array (1) are distributed at equal intervals, and the stepping angle at which the stepping motor (3) drives the reflector (2) to rotate is half the angular interval between adjacent laser light sources.

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