Junction length measuring method for light-emitting junction of semiconductor laser

Abstract

The invention relates to the technical field of small-size measurement, and provides a junction length measurement method for a light-emitting junction of a semiconductor laser. The luminous junction is placed at the focal position of the collimating lens; driving the luminous junction to generate laser so as to form a light spot on one side, far away from the luminous junction, of the collimating lens; and obtaining the junction length d of the luminous junction according to the focal length f of the collimating lens, the image height D of the light spot and the image distance L between the light spot and the collimating lens. Wherein the luminous junction located at the focus position generates laser, the laser is collimated by the collimating lens to form a large-size light spot, the junction length d of the luminous junction is obtained by measuring the image height D of the light spot and substituting the image height D into a formula d = (D * f) / L, f is the focal length of the collimating lens, L is the image distance between the light spot and the collimating lens, and the collimating lens is adopted to replace a scanning electron microscope. The technical problem that the junction length measurement cost of an existing luminous junction is high is solved, the operation is simple, and the cost is low.

Description

Technical Field

[0001] The present invention relates to the technical field of microscopic measurement, and particularly to a method for measuring the junction length of a light-emitting junction of a semiconductor laser. Background Art

[0002] With the progress of autonomous driving technology, vehicle-mounted lidar has become increasingly popular, and MEMS (Micro-Electro-Mechanical System) lidar, as one of its applications, has also been more widely used. A semiconductor laser is one of the key components of a MEMS lidar, and its performance directly affects the performance of the lidar. Since the EEL (Edge-Emitting Laser) semiconductor laser has a large spontaneous divergence angle, collimation processing is required when it is applied to a lidar. Before manufacturing an optical module, a large amount of simulation work needs to be carried out, and the accuracy of the LD (Lidar) model will directly affect the design of the collimation optical path, thus affecting the performance of the lidar.

[0003] The junction length of the light-emitting junction is an important parameter in the LD optical modeling process. However, since the size of the LD light-emitting junction is at the micron level, it cannot be measured using a conventional optical microscope, and a scanning electron microscope with a higher magnification must be used. However, the scanning electron microscope is expensive, resulting in a high cost for measuring the junction length of the light-emitting junction. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for measuring the junction length of a light-emitting junction of a semiconductor laser, aiming to solve the technical problem of the high cost of measuring the junction length of the existing light-emitting junction.

[0005] The present application provides a method for measuring the junction length of a light-emitting junction of a semiconductor laser, and the method includes the following steps:

[0006] Place the light-emitting junction at the focal position of the collimating lens;

[0007] Drive the light-emitting junction to generate laser light to form a light spot on the side of the collimating lens away from the light-emitting junction;

[0008] Obtain the junction length d of the light-emitting junction according to the focal length f of the collimating lens, the image height D of the light spot, and the image distance L of the light spot from the collimating lens.

[0009] In one embodiment, the method further includes the following steps:

[0010] Place a coordinate paper on the side of the collimating lens away from the light-emitting junction so that the light spot falls on the coordinate paper.

[0011] In one embodiment, the step of placing the coordinate paper on the side of the collimating lens away from the light-emitting junction specifically includes:

[0012] Move the coordinate paper along the normal line perpendicular to the coordinate paper so that the light spot covers the central origin of the coordinate paper.

[0013] In one embodiment, the step of obtaining the junction length of the light-emitting junction according to the focal length of the collimating lens, the image height of the light spot, and the distance between the light spot and the collimating lens specifically includes:

[0014] Use a camera to collect an image of the coordinate paper;

[0015] Identify the image of the coordinate paper to obtain the image height D of the light spot in the image;

[0016] According to d = (D * f) / L, calculate the junction length d of the light-emitting junction.

[0017] In one embodiment, the step of identifying the image of the coordinate paper to obtain the image height D of the light spot in the image specifically includes:

[0018] Rotate the image to obtain the cumulative light intensity of the light spots in multiple groups of the image in a preset direction;

[0019] Select the maximum value among the multiple groups of cumulative light intensities, and the rotation angle of the image corresponding to this maximum value is the length direction of the light-emitting junction;

[0020] Determine the image height D of the light spot according to the length direction of the light-emitting junction.

[0021] In one embodiment, before the step of using the camera to collect an image of the coordinate paper, the following steps are further included:

[0022] Place the camera and the light-emitting junction on the same side of the collimating lens, and the camera is located directly behind the collimating lens;

[0023] Adjust the pixel side of the camera to be parallel to the scale line of the coordinate paper;

[0024] Adjust the vertical distance between the camera and the optical axis of the collimating lens to be greater than 0 and less than or equal to 5 cm.

[0025] In one embodiment, the step of calculating the junction length d of the light-emitting junction specifically includes:

[0026] Electrically connect the computer to the camera to receive the image collected by the camera;

[0027] Identify the light spot in the image and the scale lines of the coordinate paper, and obtain the image height D of the light spot in the image;

[0028] Input the focal length f of the collimating lens and the image distance L from the light spot to the collimating lens, and obtain the junction length d of the light-emitting junction.

[0029] In one embodiment, the method further includes the following steps:

[0030] Use a rangefinder to obtain the image distance L.

[0031] In one embodiment, the number of the light-emitting junctions is more than two, the more than two light-emitting junctions are arranged in parallel, the interval between adjacent two light-emitting junctions is less than or equal to 5 mm, and at least one light-emitting junction is located at the focal position of the collimating lens.

[0032] In one embodiment, the value range of the image distance L is 3 m to 10 m, and the value range of the focal length f is 6 mm to 10 mm.

[0033] The beneficial effect of the method for measuring the junction length of the light-emitting junction of the semiconductor laser provided by the present invention is that the light-emitting junction located at the focal position generates laser light, and the laser light is collimated by the collimating lens to form a large-sized light spot. By measuring the image height D of the light spot and substituting it into the formula d = (D * f) / L, where f is the focal length of the collimating lens and L is the image distance from the light spot to the collimating lens, the junction length d of the light-emitting junction is obtained. The collimating lens is used instead of the scanning electron microscope, which solves the technical problem of the high cost of measuring the junction length of the existing light-emitting junction, and the operation is simple. Description of the Drawings

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0035] Figure 1 It is a schematic flow chart of the method for measuring the junction length of the light-emitting junction of the semiconductor laser provided by the embodiment of the present invention;

[0036] Figure 2 It is a schematic diagram for measuring the junction length of the light-emitting junction in this embodiment;

[0037] Figure 3 It is a schematic diagram of the device for measuring the junction length of the light-emitting junction in this embodiment;

[0038] Figure 4 It is a schematic diagram of the installation of multiple light-emitting junctions.

[0039] Among them, the reference numerals in the figures are as follows:

[0040] 10, light-emitting junction; 20, collimating lens; 30, light spot; 40, camera; 50, coordinate paper; 60, wall surface; 70, computer; 81, substrate; 82, positioning groove; 83, cover plate. Detailed implementation manners

[0041] The embodiments of the present invention will be described in detail below. The examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present invention, and should not be construed as a limitation to the present invention.

[0042] Referring throughout the specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present application. Thus, the phrases "in one embodiment" or "in some embodiments" appearing throughout the specification do not necessarily refer to the same embodiment. Additionally, in one or more embodiments, the particular features, structures, or characteristics may be combined in any suitable manner.

[0043] In the description of the present invention, it should be understood that the orientation or positional relationships indicated by the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present invention.

[0044] Furthermore, the terms "first" and "second" are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features.

[0045] In the present invention, unless otherwise clearly defined and limited, the terms "mounted", "connected", "connected to", "fixed", etc. should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the internal communication of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0046] SeeFigure 1 and Figure 2 , a method for measuring the junction length of a light-emitting junction 10 provided by the present application includes the following steps:

[0047] S100: Place the light-emitting junction 10 at the focal position of the collimating lens 20.

[0048] S200: Drive the light-emitting junction 10 to generate laser light to form a light spot 30 on the side of the collimating lens 20 away from the light-emitting junction 10.

[0049] S300: Obtain the junction length d of the light-emitting junction 10 according to the focal length f of the collimating lens 20, the image height D of the light spot 30, and the image distance L of the light spot 30 from the collimating lens 20.

[0050] Among them, the light-emitting junction 10 located at the focal position generates laser light, and the laser light is collimated by the collimating lens 20 to form a large-sized light spot 30. By measuring the image height D of the light spot 30 and substituting it into the formula d=(D*f) / L, where f is the focal length of the collimating lens 20 and L is the image distance of the light spot 30 from the collimating lens 20, the junction length d of the light-emitting junction 10 is obtained. The collimating lens 20 is used to replace the expensive and non-universal scanning electron microscope, solving the technical problem of the relatively high cost of measuring the junction length of the existing light-emitting junction 10, and the operation is simple.

[0051] In some embodiments, combined with Figure 2 , the value range of the image distance L is 3m to 10m. In this way, the value of the image distance L is greater than or equal to 3m, so that after the laser light generated by the light-emitting junction 10 is collimated by the collimating lens 20, the size of the light spot 30 will be larger, greatly reducing the measurement difficulty of the image height D of the light spot 30. At the same time, due to the relatively large image distance L, combined with d=(D*f) / L, the error of the focal length f of the collimating lens 20 and the assembly error of the light-emitting junction 10 are weakened, greatly reducing the setting accuracy requirements of the light-emitting junction 10 at the focal position and greatly reducing the manufacturing accuracy requirements of the collimating lens 20, improving the measurement accuracy of the junction length.

[0052] In addition, please also combine Figure 3 , the value of the image distance L is less than or equal to 10m, which can reduce the space requirements of the test site and the installation and adjustment difficulty of the on-site device.

[0053] Optionally, the value of the image distance L is 3m, 4m, 5m, 6m, 7m, 8m, 9m or 10m.

[0054] In some embodiments, combined with Figure 2, the value range of the focal length f is 6 mm to 10 mm. In this way, the value of the focal length f is greater than or equal to 6 mm, avoiding the distance between the light-emitting junction 10 and the collimating lens 20 being too close, which increases the operation difficulty of on-site alignment. At the same time, the value of the focal length f is less than or equal to 10 mm. Combining with d = (D * f) / L, on the one hand, it weakens the error of the focal length f of the collimating lens 20 and the assembly error of the light-emitting junction 10, greatly reducing the requirement for the setting accuracy of the light-emitting junction 10 at the focal position and greatly reducing the manufacturing accuracy requirement of the collimating lens 20, and improving the measurement accuracy of the junction length; on the other hand, it can increase the magnification of the light spot 30, which is beneficial to the measurement of the image height D of the light spot 30.

[0055] Optionally, the value of the focal length f is 6 mm, 7 mm, 8 mm, 9 mm or 10 mm.

[0056] In some embodiments, the method further includes the following steps:

[0057] S400: Use a rangefinder to obtain the image distance L. In this way, the image distance L is measured by the rangefinder. The error of the rangefinder itself is 0.0007%, and the distance measurement error is 0.17%. Overall, the error of the image distance L is extremely small, improving the measurement accuracy of the junction length d of the light-emitting junction 10.

[0058] In addition, the rangefinder can provide fast and real-time measurement results, which is beneficial to improving the measurement automation and measurement efficiency of the junction length d, saving time and human resources, and at the same time reducing the measurement error caused by human operation errors. Compared with manual measurement, which may be affected by individual differences and misjudgments of operators, the rangefinder can accurately measure through laser or other technologies during the ranging process, reducing the interference of these factors.

[0059] In some embodiments, the method further includes the following steps:

[0060] S500: Place a coordinate paper 50 on the side of the collimating lens 20 away from the light-emitting junction 10 so that the light spot 30 falls on the coordinate paper 50. In this way, the image height D of the light spot 30 can be directly measured using the scale lines on the coordinate paper 50. The cost is low, and the image height D of the light spot 30 can be obtained conveniently and quickly, and the measurement error introduced by additional operations or image processing is reduced. In addition, by projecting the light spot 30 onto the coordinate paper 50, the position and shape of the light spot 30 can be observed in real time. This is of great significance for adjusting experiments or parameters because the situation of the light spot 30 before and after modification can be directly observed and compared, helping to optimize the system settings and experimental results.

[0061] Optionally, the coordinate paper 50 is pasted on the wall 60.

[0062] In one of the embodiments, step S500 specifically includes:

[0063] S510: Move the coordinate paper 50 along the normal line perpendicular to the coordinate paper 50 so that the light spot 30 covers the central origin of the coordinate paper 50. In this way, the light spot 30 falls on the central origin of the coordinate paper 50, and the image height D of the light spot 30 can be accurately measured directly using the scale lines on the coordinate paper 50, which can minimize the measurement error caused by the offset of the light spot 30 from the center.

[0064] In some embodiments, step S300 specifically includes:

[0065] S310: Use the camera 40 to collect an image of the coordinate paper 50.

[0066] S320: Identify the image of the coordinate paper 50 and obtain the image height D of the light spot 30 in the image.

[0067] S330: Calculate the junction length d of the light-emitting junction 10 according to d = (D * f) / L.

[0068] In this way, this method uses the camera 40 to collect the light spot 30 on the coordinate paper 50 and performs coordinate system conversion to obtain the image height D of the light spot 30, which can provide more accurate image collection, can obtain more accurate data of the image height D of the light spot 30, improve the measurement accuracy. At the same time, it can identify the image of the coordinate paper 50, automatically extract the position and size information of the light spot 30, reduce manual intervention, and improve the measurement efficiency and consistency. The camera 40 can adapt to light spots 30 with different shapes, sizes and positions, provide a more flexible measurement scheme, and expand the test scenario.

[0069] In one of the embodiments, step S320 specifically includes:

[0070] S321: Rotate the image to obtain the cumulative light intensity of the light spot 30 in a preset direction for multiple groups of images.

[0071] S322: Select the maximum value from the multiple groups of cumulative light intensities, and the rotation angle of the image corresponding to this maximum value is the length direction of the light-emitting junction 10.

[0072] S323: Determine the image height D of the light spot 30 according to the length direction of the light-emitting junction 10.

[0073] The pixel side of the camera 40 is placed parallel to the length direction of the light-emitting junction 10, or the scale lines of the coordinate paper 50 are placed parallel to the length direction of the light-emitting junction 10. However, due to assembly errors, there may be an angle with the length direction of the light-emitting junction 10. Since the light intensity in the length direction of the light-emitting junction 10 follows a Gaussian distribution, it is beneficial to calculate the cumulative light intensity in the preset direction (i.e., the assumed length direction of the light-emitting junction 10). Rotate the image until the cumulative light intensity reaches the maximum value. At this time, the X-axis of the light spot 30 in the image is parallel to the length direction of the light-emitting junction 10, determining the actual length direction of the light-emitting junction 10. According to this length direction, calculate the Y-axis size of the light spot 30 at this time, which is the image height D of the light spot 30.

[0074] Specifically, in addition to using an algorithm to calculate the cumulative light intensity, during debugging, to accurately obtain the cumulative light intensity, the fiber optic array arranged in a straight line can be fixed to the coordinate paper 50 and placed on a six-axis adjustment platform. Adjust each dimension of the end of the fiber optic array close to the collimating lens 20, and place a peak power meter at the other end of the fiber optic array to monitor the output optical power in real time. When the monitored output optical power is the maximum, the arrangement direction of the fiber optic array is parallel to the length direction of the light-emitting junction 10, which is used as the X-axis of the coordinate paper 50, and the position of the coordinate paper 50 is fixed.

[0075] In one embodiment, before step S310, the method further includes the following steps:

[0076] S340: Place the camera 40 and the light-emitting junction 10 on the same side of the collimating lens 20, and the camera 40 is located directly behind the collimating lens 20. At this time, the distortion of the light spot 30 captured at the position where the camera 40 is located is small, the shape of the light spot 30 is accurate, and the measurement accuracy of the image height D of the light spot 30 is improved.

[0077] S350: Adjust the pixel side of the camera 40 to be parallel to the scale lines of the coordinate paper 50. Specifically, make the pixel grid of the camera 40 aligned and parallel to the scale lines to achieve the parallel setting of the two.

[0078] S360: Adjust the vertical distance between the camera 40 and the optical axis of the collimating lens 20 to be greater than 0 and less than or equal to 5 cm.

[0079] In this way, the camera 40 is generally located directly behind the light-emitting junction 10 but is not blocked by the light-emitting junction 10. By keeping the optical axes aligned, it can be ensured that the camera 40 can accurately capture the light spot 30 generated by the light-emitting junction 10, making the imaging position of the light spot 30 after passing through the collimating lens 20 closer to the ideal state, minimizing the distortion of the light spot 30, collecting a more real and accurate image, and thus improving the measurement accuracy.

[0080] In one embodiment, step S330 specifically includes:

[0081] S331: Electrically connect the computer 70 to the camera 40 to receive the images collected by the camera 40.

[0082] S332: Identify the light spot 30 and the scale lines of the coordinate paper 50 in the image, and obtain the image height D of the light spot 30 in the image.

[0083] S333: Input the focal length f of the collimating lens 20 and the image distance L from the light spot 30 to the collimating lens 20 to obtain the junction length d of the light-emitting junction 10.

[0084] Combined with Figure 3 , the computer 70 is used to achieve automatic measurement, greatly improving the measurement efficiency and consistency. With the processing power and algorithms of the computer 70, the measurement error can be reduced and the accuracy of the measurement results can be improved.

[0085] In summary, the laser generated by the light-emitting junction 10 is collimated by the collimating lens 20, and a clear image of the light spot 30 appears after collimation. The camera 40 is located directly behind the light-emitting junction 10 and is approximately coaxial with the light-emitting junction 10. The scale lines of the coordinate paper 50 are parallel to the pixels of the camera 40, and the light spot 30 falls on the center of the coordinate paper 50. The image of the coordinate paper 50 is collected to realize the conversion between the coordinate system of the camera 40 and the world coordinate system. The image of the light spot 30 and the background image are collected, the size of the light spot 30 in the world coordinate system is calculated, and the size of the junction length is calculated.

[0086] In this way, the effective measurement of the junction length of the light-emitting junction 10 can be realized by using the present invention, and the cost is relatively low. It only requires an industrial camera 40 and a collimating lens 20 to achieve. The main sources of error in the present invention are lens processing error, ranging error, and light spot 30 size calculation error. The lens focal length processing error is 1%. For the distance measurement error, the distance is obtained by testing with a rangefinder, and its error includes the error of the rangefinder itself and the distance measurement error. The error of the rangefinder itself is 0.0007%, and the distance measurement error is 0.17%. The maximum light spot 30 test error is 2%. After error synthesis, it is 2.24%. That is to say, the test error using the present invention can be controlled within 3%.

[0087] In some embodiments, combined with Figure 3 and Figure 4 , the number of the light-emitting junctions 10 is more than two, and the more than two light-emitting junctions 10 are arranged in parallel. The interval between two adjacent light-emitting junctions 10 is less than or equal to 5 mm, and at least one light-emitting junction 10 is located at the focal position of the collimating lens 20. In this way, the present method can measure the junction lengths of multiple groups of light-emitting junctions 10 at one time and improve the measurement accuracy of the junction length by taking the average value. At the same time, the interval between the light-emitting junctions 10 is small, and the corresponding light spots 30 have high consistency, reducing the error.

[0088] In some embodiments, combined with Figure 3 and Figure 4, the interval deviation between any two adjacent light-emitting junctions 10 is 1 μm to 5 μm. There is only an interval of the order of micrometers between the light-emitting junctions 10, greatly reducing the interval between the light-emitting junctions 10, which is beneficial to reducing the image height difference of the light spots 30 of different light-emitting junctions 10 and can generally improve the measurement accuracy.

[0089] In one embodiment, in combination with Figure 3 and Figure 4 , more than two light-emitting junctions 10 are arranged on the substrate 81. The substrate 81 has a plurality of positioning grooves 82. The light-emitting junctions 10 are positioned by the two side surfaces of the positioning grooves 82, and each light-emitting junction 10 is fixed in a positioning groove 82. The arrangement of the positioning grooves 82 can accurately control the interval between adjacent light-emitting junctions 10, so that the interval arrangement of the light-emitting junctions 10 is accurately controllable, simplifying the assembly of the light-emitting junctions 10.

[0090] Specifically, a light-transmitting cover plate 83 is fixedly arranged on the side of the light-emitting junction 10 facing away from the positioning groove 82 to fix the light-emitting junction 10 in the positioning groove 82. In this way, the upper and lower sides of the light-emitting junction 10 are limited between the substrate 81 and the cover plate 83, so that the position of the light-emitting junction 10 is fixed. And compared with connection methods such as welding, clamping, and hot-melt connection, the light-emitting junction 10 is fixed between the substrate 81 and the cover plate 83, and the assembly process is simple and reliable.

[0091] Optionally, the material of the substrate 81 is glass. The material of the cover plate 83 is glass.

[0092] Optionally, the light-emitting junction 10 is fixedly bonded in the positioning groove 82 by dispensing. Compared with welding, clamping, and hot-melt connection, the glue has fluidity and can adapt to the gap between the light-emitting junction 10 and the positioning groove 82 to bond and fix the light-emitting junction 10, without the need to accurately control the dispensing position, dispensing thickness, dispensing area, etc., and is suitable for connecting the light-emitting junctions 10 on a micro scale, greatly simplifying the fixing method of the light-emitting junctions 10.

[0093] Specifically, the positioning groove 82 is etched on one side surface of the substrate 81. The substrate 81 is made into the positioning groove 82 by an etching process. Compared with other processing methods (such as machining), the etching process is easier to control the dimensional accuracy and shape of the positioning groove 82, can machine the positioning groove 82 on the micrometer and nanometer scales, and control the interval between the positioning grooves 82 at the micrometer level.

[0094] In some embodiments, step S100 specifically includes:

[0095] S110: Adjust the position of the light-emitting junction 10 until the light spot 30 on the coordinate paper 50 is the clearest. In this way, the light-emitting junction 10 is placed at the focal position. First, place the light-emitting junction 10 at the focal length position of the collimating lens 20, and then fine-tune to make the light spot 30 the clearest.

[0096] Specifically, it can be determined clearly by the intensity of the light spot 30.

[0097] In one embodiment, step S110 is specifically as follows:

[0098] S111: Repeatedly adjust the position of the light-emitting junction 10 in the first direction, the second direction, and the third direction that are perpendicular to each other in pairs until the intensity decreases when continuing to adjust the position of the light-emitting junction 10 in any one of the first direction, the second direction, and the third direction. In other words, when the light-emitting junction 10 is adjusted to a certain position, no matter whether it is moved in the first direction, the second direction, or the third direction, the intensity of the light spot 30 will become smaller, indicating that the position adjustment of the light-emitting junction 10 is completed at this time, which is beneficial to quickly complete the alignment operation.

[0099] The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for measuring the junction length of a semiconductor laser emitting junction, characterized in that, The method includes the following steps: Place the light-emitting junction at the focal position of the collimating lens; Drive the light-emitting junction to generate laser light, so as to form a light spot on the side of the collimating lens away from the light-emitting junction; Obtain the junction length d of the light-emitting junction according to the focal length f of the collimating lens, the image height D of the light spot, and the image distance L of the light spot from the collimating lens.

2. The method for measuring the junction length of the light-emitting junction of a semiconductor laser according to claim 1, characterized in that, The method further includes the following steps: Place a coordinate paper on the side of the collimating lens away from the light-emitting junction, so that the light spot falls on the coordinate paper.

3. The method for measuring the junction length of the light-emitting junction of a semiconductor laser according to claim 2, wherein: The step of placing the coordinate paper on the side of the collimating lens away from the light-emitting junction specifically includes: Move the coordinate paper along the normal line perpendicular to the coordinate paper, so that the light spot covers the central origin of the coordinate paper.

4. The method for measuring the junction length of the light-emitting junction of a semiconductor laser according to claim 2, wherein The step of obtaining the junction length of the light-emitting junction according to the focal length of the collimating lens, the image height of the light spot, and the distance of the light spot from the collimating lens specifically includes: Use a camera to collect an image of the coordinate paper; Identify the image of the coordinate paper, and obtain the image height D of the light spot in the image; Calculate the junction length d of the light-emitting junction according to d = (D * f) / L.

5. The method for measuring the junction length of the light-emitting junction of a semiconductor laser according to claim 4, characterized in that, The step of identifying the image of the coordinate paper and obtaining the image height D of the light spot in the image specifically includes: Rotate the image to obtain the cumulative light intensity of the light spots of multiple groups of the images in a preset direction; Select the maximum value from multiple groups of the cumulative light intensities, and the rotation angle of the image corresponding to this maximum value is the length direction of the light-emitting junction; Determine the image height D of the light spot according to the length direction of the light-emitting junction.

6. The method for measuring the junction length of the light-emitting junction of a semiconductor laser according to claim 4, characterized in that: Before the step of using the camera to collect an image of the coordinate paper, the following steps are further included: Place the camera and the light-emitting junction on the same side of the collimating lens, and the camera is located directly behind the collimating lens; Adjust the pixel side of the camera to be parallel to the scale line of the coordinate paper; Adjust the vertical distance between the camera and the optical axis of the collimating lens to be greater than 0 and less than or equal to 5 cm.

7. The method for measuring the junction length of the light-emitting junction of a semiconductor laser according to claim 5, characterized in that, The step of calculating the junction length d of the light-emitting junction specifically includes: Electrically connect a computer to the camera to receive the image collected by the camera; Identify the light spot and the scale line of the coordinate paper in the image, and obtain the image height D of the light spot in the image; Input the focal length f of the collimating lens and the image distance L of the light spot from the collimating lens to obtain the junction length d of the light-emitting junction.

8. The method for measuring the junction length of the light-emitting junction of a semiconductor laser according to claim 1, characterized in that, The method further includes the following steps: Use a rangefinder to obtain the image distance L.

9. The method for measuring the junction length of the light-emitting junction of a semiconductor laser according to claim 1, characterized in that: The number of the light-emitting junctions is two or more, two or more of the light-emitting junctions are arranged in parallel, the interval between adjacent two of the light-emitting junctions is less than or equal to 5 mm, and at least one of the light-emitting junctions is located at the focal position of the collimating lens.

10. The method for measuring the junction length of the light-emitting junction of a semiconductor laser according to any one of claims 1 to 9, characterized in that: The value range of the image distance L is 3 m to 10 m, and the value range of the focal length f is 6 mm to 10 mm.

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