Device and method for testing beam divergence angle of semiconductor laser

Abstract

The invention relates to a semiconductor laser beam divergence angle testing device and method, and belongs to the technical field of semiconductor lasers, the semiconductor laser beam divergence angle testing device comprises a shell, an image sensor A, an image sensor B and a spectroscope are arranged in the shell, and the image sensor A and the image sensor B are arranged at the bottom of the shell and on a middle partition plate respectively; the receiving surfaces of the image sensor A and the image sensor B are perpendicular to each other; data collected by the image sensor A and the image sensor B are transmitted to the computer, the spectroscope is fixed on the shell and forms an included angle of 45 degrees with receiving surfaces of the image sensor A and the image sensor B, and an intersection point of perpendicular bisectors of the receiving surfaces of the image sensor A and the image sensor B is just located on a reflecting surface of the spectroscope. According to the invention, the measured laser beam is split and enters the image sensor at different optical paths to obtain two groups of light intensity distribution data, and the light beam divergence angle can be calculated according to the optical path difference and the light intensity distribution expansion degree.

Description

Technical Field

[0001] The invention relates to a semiconductor laser light beam divergence angle testing device and a testing method, belonging to the technical field of semiconductor lasers. Background Art

[0002] As semiconductor laser technology matures, it has entered many application fields such as consumer electronics, industrial processing, military defense, scientific research, etc. When it comes to application scenarios such as indication, display, and measurement, there are often certain requirements for the morphology of the laser spot, so it is necessary to test the laser beam divergence angle.

[0003] In the national standard GB / T 31359-2015 "Semiconductor Laser Test Methods", two common divergence angle test methods are listed. The first is the spot size method, which directly measures the laser beam through CCD, or shoots its diffuse reflection imaging spot, converts the light intensity into a gray value-pixel curve, and obtains the light intensity distribution of the beam, so as to calculate the beam divergence angle. The second is the scanning method, which uses a rotating platform, a rotating sampling device or a laser to directly measure the laser intensity at different angles, obtain the light intensity distribution of the beam, and thus calculate the beam divergence angle.

[0004] For the spot size method, the distance from the light-emitting surface of the laser to be tested to the CCD must be fixed before the divergence angle can be calculated using the trigonometric principle; the light beam cannot have a deflection angle, otherwise the measured spot size will deviate from the actual beam propagation direction, affecting the test accuracy. For the scanning method, it is also necessary to fix the distance from the laser to be tested to the laser intensity sampling device, and because of the need for moving parts such as a rotating platform, the volume of the test equipment is often large. Therefore, in practical applications, the above two test methods have certain limitations. If the divergence angle test is to be performed on a laser that cannot be fixed individually, or the test space is relatively limited, the above methods cannot be used.

[0005] To solve the above problems, it is necessary to design a semiconductor laser beam divergence angle test device and test method, which does not require a fixed distance from the laser machine to the test device, is insensitive to beam deviation angles, has no moving parts, has a compact structure, and can be flexibly used in a variety of scenarios. Summary of the invention

[0006] In view of the shortcomings of the prior art, the present invention provides a semiconductor laser beam divergence angle testing device and method. By splitting the laser beam to be tested and entering the image sensor at different optical path lengths, two sets of light intensity distribution data are obtained, and the beam divergence angle can be calculated based on the optical path difference and the degree of expansion of the light intensity distribution.

[0007] The present invention adopts the following technical solution:

[0008] A semiconductor laser beam divergence angle test device comprises a housing, wherein an image sensor A, an image sensor B and a spectroscope are arranged in the housing, the image sensor A and the image sensor B are arranged on the bottom and the middle partition of the housing respectively, and the receiving surfaces of the image sensor A and the image sensor B are perpendicular to each other; the data collected by the image sensor A and the image sensor B are transmitted to a computer, and the divergence angle is calculated by the computer;

[0009] The beam splitter is fixed on the housing and forms an angle of 45° with the receiving surfaces of image sensor A and image sensor B. The intersection of the perpendicular bisectors of the receiving surfaces of image sensor A and image sensor B is located exactly on the reflecting surface of the beam splitter. The distance from the intersection to the receiving surface of image sensor A is d1, and the distance to the receiving surface of image sensor B is d2. The difference d=d2-d1 is a fixed value.

[0010] Preferably, the image sensor A and the image sensor B are both welded to a sensor driving circuit, and the sensor driving circuit is welded to the bottom and the middle partition of the housing.

[0011] Preferably, an incident opening is provided on a side of the housing close to the beam splitter, so that the measured light beam is incident on the beam splitter through the incident opening.

[0012] Preferably, a card slot is provided at the incident opening for installing a filter, which can be used to isolate the interference of ambient light, or serve as an attenuation plate to reduce the intensity of the incident laser and prevent the image sensor from photosensitivity saturation.

[0013] Preferably, the side walls of the housing, the bottom of the housing and the middle partition are all provided with fixing grooves for fixing the sensor driving circuit and the spectroscope.

[0014] Preferably, the bottom of the shell has a data line interface for transmitting data; the outside of the shell has several screw holes for fixing the shell components, and all the shell blocks are fixed together by screws, and the position of the internal components is stabilized.

[0015] Preferably, the image sensor A and the image sensor B have the same structure, which is a CCD or CMOS structure, and can convert the light intensity received by each pixel point on the receiving surface into a grayscale value electrical signal for computer reading and analysis.

[0016] A method for testing the semiconductor laser beam divergence angle test device as described above comprises:

[0017] The laser beam under test enters the test device through the incident opening. After reaching the spectroscope, part of the beam is reflected to the image sensor A, forming a light spot on the receiving surface, and is converted by the image sensor A into grayscale value-pixel array data, and then the light intensity distribution data can be obtained; the other part of the beam continues to propagate through the spectroscope and reaches the image sensor B of the middle partition, forming a light spot on the receiving surface, and is converted by the image sensor B into grayscale value-pixel array data, and then the light intensity distribution data can be obtained; the main purpose of the light intensity distribution data is to determine the boundary of the beam on the sensor receiving surface; according to the pixel position where the boundary is located, the coordinate values ​​of the boundary in the vertical and horizontal directions are obtained. When calculating the divergence angle according to FWHM, the pixel with the maximum light intensity of 50% is the boundary; when calculating the divergence angle according to 1 / e2, the pixel with the maximum light intensity of 13.5% is the boundary.

[0018] The optical path difference between the two groups of light beams after splitting is the distance difference between the intersection points of the perpendicular bisectors of the receiving surfaces of the two groups of image sensors. The beam divergence angle can be calculated based on the two groups of light intensity distribution data and the optical path difference.

[0019] Preferably, the laser beam to be tested enters the test device through the incident opening, and after reaching the beam splitter, 50% of the intensity of the beam is reflected to the image sensor A, forming a light spot No. 1 on the receiving surface, and is converted by the image sensor A into the gray value-pixel array data of the light spot No. 1, thereby obtaining the light intensity distribution data; the other 50% of the intensity of the beam continues to propagate through the beam splitter, reaches the image sensor B of the middle partition, forms a light spot No. 2 on the receiving surface, and is converted by the image sensor B into the gray value-pixel array data of the light spot No. 2, thereby obtaining the light intensity distribution data;

[0020] Assume that there is a virtual image sensor, which is located behind the beam splitter, and the receiving surface of the virtual image sensor is mirror-symmetrical with the receiving surface of the image sensor A along the reflecting surface of the beam splitter. According to the principle of symmetry, after the measured light beam passes through the beam splitter, the virtual light spot formed on the receiving surface of the virtual image sensor should have the same size and the same light intensity distribution as the light spot No. 1 on the image sensor A; therefore, the light intensity distribution data of the light spots No. 1 and No. 2 can be regarded as the light intensity distribution data of the measured light beam with 50% intensity reaching the virtual image sensor and the image sensor B, and the distance between the virtual image sensor and the image sensor B is exactly the known fixed value d=d2-d1;

[0021] The vertical divergence angle θ of the measured light beam is divided into two parts θ1 and θ2 by the horizontal line. The light spot of the light beam on the image sensor B has a maximum light intensity of 50% at the upper end A and a lower end B. The center point of the receiving surface is the origin of the coordinates. The vertical coordinates of A and B on the receiving surface are y1 and y2 respectively (the coordinates are obtained through the pixel coordinates and the pixel spacing).

[0022] Since the receiving surface of the virtual image sensor is mirror-symmetrical with the receiving surface of the image sensor A along the reflective surface of the beam splitter, the upper end of the 50% boundary of the maximum light intensity of the virtual light spot behind the reflective surface of the beam splitter is A', and the lower end is B', and the virtual vertical coordinates on the receiving surface should also be y1 and y2; the light spot of the light beam on the image sensor B has a maximum light intensity of 50% at the upper end C and the lower end D, and the center point of the receiving surface is the origin of the coordinates. The vertical coordinates of C and D on the receiving surface are y3 and y4 respectively;

[0023] Since the intersection of the perpendicular bisectors of the receiving surfaces of the two groups of image sensors is located exactly on the reflection surface of the beam splitter, the perpendicular bisectors of the receiving surfaces of the virtual image sensor and the middle partition image sensor B completely coincide, and the distance between the two surfaces is exactly d; therefore, the vertical height difference of the four points A', B', C, and D in the device can be directly calculated using their respective vertical coordinates, and then the vertical divergence angle (FWHM) of the light beam can be calculated:

[0024]

[0025] It can be seen that even when the incident light has a certain deviation angle (θ1≠θ2), ​​the device can also calculate the divergence angle based on the grayscale value-pixel array data, which has a certain fault tolerance.

[0026] For any details not provided in the present invention, please refer to the prior art.

[0027] The beneficial effects of the present invention are:

[0028] The semiconductor laser beam divergence angle testing device and testing method of the present invention do not need to fix the distance from the laser to the testing device, are insensitive to beam deviation angles, have a certain fault tolerance, have no moving parts, and have a compact structure, and can be flexibly used in a variety of scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The drawings in the specification, which constitute a part of the present application, are used to provide further understanding of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute improper limitations on the present application.

[0030] Figure 1 It is a schematic diagram of the internal structure of the semiconductor laser beam divergence angle testing device of the present invention;

[0031] Figure 2 This is a schematic diagram of the installation positions of image sensor A and image sensor B;

[0032] Figure 3 This is a schematic diagram of the installation position of the beam splitter;

[0033] Figure 4Schematic diagram of the shell structure, where (a) is the external structure, (b) is a schematic diagram of the filter and the incident opening position, and (c) is a schematic diagram of the fixing slot structure;

[0034] Figure 5 Schematic diagram of the beam propagation path, (a) is a stereogram, (b) is a front view;

[0035] Figure 6 This is a schematic diagram of the calculation process of the divergence angle test example;

[0036] Figure 7 This is a schematic diagram of the origin coordinate determination method;

[0037] In the figure, 1-beam splitter, 2-image sensor A, 3-image sensor B, 4-housing, 5-middle partition, 6-sensor driving circuit, 7-incident opening, 8-card slot, 9-filter, 10-fixing slot, 11-screw hole, 12-light spot No. 1, 13-light spot No. 2, 14-virtual image sensor, 15-virtual light spot. DETAILED DESCRIPTION

[0038] In order to enable those skilled in the art to better understand the technical solutions in this specification, the technical solutions in the embodiments of the present invention are clearly and completely described below in conjunction with the drawings in the implementation of this specification, but are not limited to this. Anything not fully described in the present invention shall be based on the conventional technology in the art.

[0039] Example 1

[0040] A semiconductor laser beam divergence angle test device, such as Figure 1 As shown, it includes a housing 4, in which an image sensor A2, an image sensor B3 and a spectroscope 1 are arranged, the image sensor A2 and the image sensor B3 are arranged on the bottom and the middle partition 5 of the housing respectively, and the receiving surfaces of the image sensor A2 and the image sensor B3 are perpendicular to each other; the data collected by the image sensor A2 and the image sensor B3 are transmitted to a computer, and the divergence angle is calculated by the computer;

[0041] like Figure 3 As shown, the beam splitter 1 is fixed on the housing 4, and forms an angle of 45° with the receiving surfaces of the image sensor A2 and the image sensor B3. The intersection of the perpendicular bisectors of the receiving surfaces of the image sensor A2 and the image sensor B3 is located exactly on the reflecting surface of the beam splitter 1. The distance from the intersection to the receiving surface of the image sensor A2 is d1, and the distance to the receiving surface of the image sensor B3 is d2. The difference d=d2-d1 is a fixed value.

[0042] Example 2

[0043] A semiconductor laser beam divergence angle testing device, as described in Example 1, except that Figure 2 As shown, the image sensor A2 and the image sensor B3 are both welded on the sensor driving circuit 6, and the sensor driving circuit 6 is welded on the bottom and the middle partition of the housing.

[0044] Example 3

[0045] A semiconductor laser beam divergence angle testing device is as described in Example 2, except that an incident opening 7 is provided on the side of the housing 4 close to the beam splitter 1, so that the measured beam is incident on the beam splitter 1 through the incident opening 7.

[0046] A card slot 8 is provided at the incident opening 7 for installing a filter 9, which can be used to isolate the interference of ambient light, or as an attenuation plate to reduce the intensity of the incident laser and prevent the image sensor from being saturated.

[0047] The side wall of the housing, the bottom of the housing and the middle partition plate 5 are all provided with fixing grooves 10 for fixing the sensor driving circuit and the spectroscope.

[0048] Example 4

[0049] A semiconductor laser beam divergence angle testing device, as described in Example 3, except that Figure 5 As shown, the bottom of the housing 4 is provided with a data line interface for transmitting data; the outside of the housing is provided with several screw holes 11 for fixing the housing components, and all the housing blocks are fixed together by screws, and the position of the internal components is stabilized.

[0050] Image sensor A and image sensor B have the same structure, which is a CCD structure, and can convert the light intensity received by each pixel on the receiving surface into a grayscale value electrical signal for computer reading and analysis.

[0051] Example 5

[0052] A method for testing the semiconductor laser beam divergence angle test device as described above comprises:

[0053] The laser beam to be tested enters the test device through the incident opening 7. After reaching the beam splitter 1, 50% of the intensity of the beam is reflected to the image sensor A2, forming a light spot 12 No. 1 on the receiving surface, and is converted by the image sensor A2 into the gray value-pixel array data of the light spot 1, thereby obtaining the light intensity distribution data; the other 50% of the intensity of the beam continues to propagate through the beam splitter 1, reaches the image sensor B3 of the middle partition, forms a light spot 13 No. 2 on the receiving surface, and is converted by the image sensor B3 into the gray value-pixel array data of the light spot 2, thereby obtaining the light intensity distribution data;

[0054] Assume that there is a virtual image sensor 14, which is located behind the beam splitter 1, and the receiving surface of the virtual image sensor 14 is mirror-symmetrical with the receiving surface of the image sensor A2 along the reflective surface of the beam splitter 1. According to the principle of symmetry, after the measured light beam passes through the beam splitter 1, the virtual light spot 15 formed on the receiving surface of the virtual image sensor 14 should have the same size and the same light intensity distribution as the light spot No. 1 12 on the image sensor A2; therefore, the light intensity distribution data of the light spot No. 1 12 and the light spot No. 2 13 can be regarded as the light intensity distribution data of the measured light beam with 50% intensity reaching the virtual image sensor and the image sensor B, and the distance between the virtual image sensor and the image sensor B is exactly the known fixed value d=d2-d1;

[0055] The grayscale value-pixel array data provided by the image sensor represents the relative light intensity at each location on the receiving surface. According to the divergence angle calculation method selected by the user, the spot boundary size data required for calculation can be obtained. Taking the calculation of the vertical divergence angle of the spot according to FWHM (full width at half maximum) as an example, the measurement problem is converted into a relatively simple mathematical problem.

[0056] like Figure 6 As shown, the vertical divergence angle θ of the measured light beam is divided into two parts θ1 and θ2 by the horizontal line. The light spot of the light beam on the image sensor B has a maximum light intensity of 50% at the upper end A and a lower end B, and the center point of the receiving surface is the origin of the coordinates; the vertical coordinates of A and B on the receiving surface are y1 and y2 respectively (the coordinates are obtained through the pixel coordinates and the pixel spacing);

[0057] The coordinate origin is defined as follows:

[0058] The device should be calibrated once before the first use. Use a beam of light perpendicular to the receiving surface of the middle partition image sensor B to illuminate the device, which will form images on the two image sensors A and B respectively; the position of the pixel with the maximum light intensity of the two spot images is the coordinate origin of each receiving surface (see Figure 7 ). After this calibration, assuming that an ideal light beam with a diameter of only 1 pixel and a divergence angle of 0 is incident vertically on this device, the image coordinates formed on the two image sensors should be consistent.

[0059] Since the receiving surface of the virtual image sensor is mirror-symmetrical with the receiving surface of the image sensor A along the reflective surface of the beam splitter, the upper end of the 50% boundary of the maximum light intensity of the virtual light spot behind the reflective surface of the beam splitter is A', and the lower end is B', and the virtual vertical coordinates on the receiving surface should also be y1 and y2; the light spot of the light beam on the image sensor B has a maximum light intensity of 50% at the upper end C and the lower end D, and the center point of the receiving surface is the origin of the coordinates. The vertical coordinates of C and D on the receiving surface are y3 and y4 respectively;

[0060] Since the intersection of the perpendicular midlines of the receiving surfaces of the two groups of image sensors is exactly located on the reflective surface of the beam splitter 1, the perpendicular midlines of the receiving surfaces of the virtual image sensor 14 and the middle partition image sensor B3 completely coincide, and the distance between the two surfaces is exactly d; therefore, the vertical height difference of the four points A', B', C, and D in the device can be directly calculated using their respective vertical coordinates, and then the vertical divergence angle (FWHM) of the light beam can be calculated:

[0061]

[0062] It can be seen that even when the incident light has a certain deviation angle (θ1≠θ2), ​​the device can also calculate the divergence angle based on the grayscale value-pixel array data, which has a certain fault tolerance.

[0063] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A semiconductor laser beam divergence angle test device, characterized in that: The invention comprises a housing, wherein an image sensor A, an image sensor B and a spectroscope are arranged in the housing, the image sensor A and the image sensor B are arranged on the bottom and the middle partition of the housing respectively, and the receiving surfaces of the image sensor A and the image sensor B are perpendicular to each other; the data collected by the image sensor A and the image sensor B are transmitted to a computer; The beam splitter is fixed on the housing and forms an angle of 45° with the receiving surfaces of image sensor A and image sensor B. The intersection of the perpendicular bisectors of the receiving surfaces of image sensor A and image sensor B is located exactly on the reflecting surface of the beam splitter. The distance from the intersection to the receiving surface of image sensor A is d1, and the distance to the receiving surface of image sensor B is d2. The difference d=d2-d1 is a fixed value.

2. The semiconductor laser beam divergence angle testing device according to claim 1, characterized in that: The image sensor A and the image sensor B are both welded on the sensor driving circuit, and the sensor driving circuit is welded on the bottom and the middle partition of the housing.

3. The semiconductor laser beam divergence angle testing device according to claim 2, characterized in that: An incident opening is arranged on one side of the housing close to the beam splitter, so that the measured light beam is incident on the beam splitter through the incident opening.

4. The semiconductor laser beam divergence angle testing device according to claim 3, characterized in that: The incident opening is provided with a slot for installing a filter.

5. The semiconductor laser beam divergence angle testing device according to claim 4, characterized in that: The side wall of the shell, the bottom of the shell and the middle partition are all provided with fixing grooves for fixing the sensor driving circuit and the spectroscope.

6. The semiconductor laser beam divergence angle testing device according to claim 5, characterized in that: The bottom of the shell is provided with a data line interface for transmitting data; the outside of the shell is provided with a plurality of screw holes for fixing the shell components.

7. The semiconductor laser beam divergence angle testing device according to claim 6, characterized in that: The image sensor A and the image sensor B have the same structure, which is a CCD or CMOS structure, and can convert the light intensity received by each pixel point on the receiving surface into a grayscale value electrical signal for computer reading and analysis.

8. A method for testing the semiconductor laser beam divergence angle testing device according to claim 7, characterized in that: include: The laser beam under test enters the test device through the incident opening. After reaching the beam splitter, part of the beam is reflected to the image sensor A, forming a light spot on the receiving surface, and is converted into grayscale value-pixel array data by the image sensor A, thereby obtaining the light intensity distribution data; the other part of the beam continues to propagate through the beam splitter and reaches the image sensor B of the middle partition, forming a light spot on the receiving surface, and is converted into grayscale value-pixel array data by the image sensor B, thereby obtaining the light intensity distribution data; the optical path difference between the two groups of light beams after the splitting is the distance difference between the receiving surfaces of the two groups of image sensors at the intersection of the perpendicular bisectors of the receiving surfaces. The beam divergence angle can be calculated based on the two groups of light intensity distribution data and the optical path difference.

9. The test method of the semiconductor laser beam divergence angle test device according to claim 8, characterized in that: The laser beam under test enters the test device through the incident opening. After reaching the beam splitter, 50% of the intensity of the beam is reflected to the image sensor A, forming a light spot No. 1 on the receiving surface, and is converted by the image sensor A into the gray value-pixel array data of the light spot No. 1, thereby obtaining the light intensity distribution data; the other 50% of the intensity beam continues to propagate through the beam splitter, reaches the image sensor B of the middle partition, forms a light spot No. 2 on the receiving surface, and is converted by the image sensor B into the gray value-pixel array data of the light spot No. 2, thereby obtaining the light intensity distribution data; Assume that there is a virtual image sensor, which is located behind the beam splitter, and the receiving surface of the virtual image sensor is mirror-symmetrical with the receiving surface of the image sensor A along the reflecting surface of the beam splitter. According to the principle of symmetry, after the measured light beam passes through the beam splitter, the virtual light spot formed on the receiving surface of the virtual image sensor should have the same size and the same light intensity distribution as the light spot No. 1 on the image sensor A; therefore, the light intensity distribution data of the light spots No. 1 and No. 2 can be regarded as the light intensity distribution data of the measured light beam with 50% intensity reaching the virtual image sensor and the image sensor B, and the distance between the virtual image sensor and the image sensor B is exactly the known fixed value d=d2-d1; The vertical divergence angle θ of the measured light beam is divided into two parts θ1 and θ2 by the horizontal line. The light spot of the light beam on the image sensor B has a maximum light intensity of 50% at the upper end A and a lower end B. The center point of the receiving surface is the origin of the coordinates. The vertical coordinates of A and B on the receiving surface are y1 and y2 respectively. Since the receiving surface of the virtual image sensor is mirror-symmetrical with the receiving surface of the image sensor A along the reflective surface of the beam splitter, the upper end of the 50% boundary of the maximum light intensity of the virtual light spot behind the reflective surface of the beam splitter is A', and the lower end is B', and the virtual vertical coordinates on the receiving surface should also be y1 and y2; the light spot of the light beam on the image sensor B has a maximum light intensity of 50% at the upper end C and the lower end D, and the center point of the receiving surface is the origin of the coordinates. The vertical coordinates of C and D on the receiving surface are y3 and y4 respectively; Since the intersection of the perpendicular bisectors of the receiving surfaces of the two groups of image sensors is located exactly on the reflection surface of the beam splitter, the perpendicular bisectors of the receiving surfaces of the virtual image sensor and the middle partition image sensor B completely coincide, and the distance between the two surfaces is exactly d; therefore, the vertical height difference of the four points A', B', C, and D in the device is directly calculated using their respective vertical coordinates, and then the vertical divergence angle of the light beam is calculated:

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