A laser receiving lens focal plane adjusting device and method

Abstract

This invention proposes a focal plane adjustment device and method for a laser receiving lens, relating to the field of laser ranging and illumination technology. The focal plane adjustment device has a cylindrical main body with an optical path along its axis. One end of the optical path extends to a predetermined distance from the end face of the cylindrical main body, and the other end penetrates the cylindrical main body. A central hole is formed at the center of the end face of the cylindrical main body, communicating with the optical path. The focal plane adjustment method includes the following steps: inserting the focal plane adjustment device into a detector mounting base; adjusting the focal plane position using a focus meter to ensure a clear image of the focal plane within the central hole; translating the detector mounting base to align the center of the focal plane image with the center of the central hole; and replacing the focal plane adjustment device with an APD avalanche photodetector. This invention effectively avoids the impact of an excessively large front-end aperture on adjustment accuracy, maximizes the detection capability of the optical signal, improves the laser ranging and illumination receiving capability, and has versatility.

Description

Technical Field

[0001] This invention relates to the field of laser rangefinder technology, and in particular to a laser receiving lens focal plane adjustment device and method. Background Technology

[0002] Laser ranging technology is a method that uses a laser beam to illuminate a target and receives the reflected laser beam to calculate the target's distance. In laser ranging, the receiving system is a crucial component. When the laser beam illuminates the target, the target reflects the laser beam into the receiving system. The receiving system's optical lens group receives the returned laser beam, focuses it, and then passes it through an APD (Avalanche Photodetector) to convert the optical signal into an electrical signal. The time interval between the laser's emission and the return of the received signal is calculated to determine the target's distance.

[0003] In related technologies, a receiver optical assembly is connected to a detector mounting base, which houses the detector. The receiver optical assembly focuses the received parallel light at a focal point. The detector mounting base is installed between the focusing optical paths, and the detector is assembled at the focal point of the receiver optical assembly. The detector mounting base is designed with an aperture, which is typically large (approximately φ2mm in diameter) to meet light transmission requirements. After receiving and focusing the returned light beam, the receiver optical assembly illuminates the photosensitive surface of the APD avalanche photodetector. Focal plane adjustment is achieved by adjusting the thickness of the gasket between the receiver optical assembly and the detector mounting base, thereby maximizing detection capability.

[0004] The usual debugging method is as follows: First, use a focus meter to adjust the focal plane, and adjust the thickness of the adjusting shims so that the image on the focal plane (usually a crosshair) is clear 1.4mm ± 0.1mm above the aperture (the optimal position determined by experiments); then, move the detector mounting base to center the image on the focal plane in the aperture. However, there are some problems in the above debugging process.

[0005] First, because the aperture is relatively large, it is difficult to determine whether the focal plane image is centered in the aperture when observed with the naked eye. This results in vertical and horizontal offset. When the beam is focused and illuminates the photosensitive surface of the APD avalanche photodetector, there is an offset phenomenon or the focal point shifts out of the photosensitive surface. This causes a significant reduction in the light signal received by the APD avalanche photodetector, affecting the photoelectric conversion efficiency, reducing the detection capability, and decreasing the ranging capability. Summary of the Invention

[0006] To overcome the shortcomings of the above-mentioned adjustment methods and devices, the present invention provides a laser receiving lens focal plane adjustment device and method to ensure that the laser beam is accurately focused on the APD avalanche photodetector, thereby improving detection capability and ranging accuracy.

[0007] Regarding the focal plane adjustment device for a laser receiving lens, the present invention provides a focal plane adjustment device for a laser receiving lens to solve the aforementioned technical problem, comprising:

[0008] The laser receiving lens focal plane adjustment device is used to simulate the APD avalanche photodetector.

[0009] The laser receiving lens focal plane adjustment device includes a cylindrical body, and the cylindrical body includes a mounting section that is connected to and cooperates with the detector mounting base;

[0010] A light path is provided at the center of the cylindrical body. One end of the light path extends to a set distance from the end face of the cylindrical body near the mounting section, and the other end passes through the cylindrical body.

[0011] A central hole is provided at the center of the end face of the cylindrical body near the mounting section, and the central hole is connected to the optical path.

[0012] As an improvement to the focal plane adjustment device of the laser receiving lens, the diameter of the central small hole gradually decreases from the end face of the cylindrical body near the mounting section to the bottom surface of the optical path, forming a conical structure.

[0013] As an improvement to the focal plane adjustment device of the laser receiving lens, the included angle formed by the axial section of the central small hole is 118 degrees.

[0014] As an improvement to the focal plane adjustment device of the laser receiving lens, the shape and size of the end of the central aperture near the bottom surface of the optical path are consistent with the shape and size of the photosensitive surface of the detector.

[0015] As an improvement to the focal plane adjustment device of the laser receiving lens, the diameter of the end of the central aperture near the bottom of the optical path is 0.2 mm.

[0016] As an improvement to the focal plane adjustment device for the laser receiving lens, one end of the optical path extends to an end face 1.4 mm away from the end of the cylindrical body near the mounting section.

[0017] As an improvement to the focal plane adjustment device of the laser receiving lens, the width of the optical path is greater than the maximum diameter of the central aperture.

[0018] As an improvement to the focal plane adjustment device of the laser receiving lens, the mounting section is inserted into the detector mounting base for contact.

[0019] As an improvement to the focal plane adjustment device of the laser receiving lens, the mounting section includes a limiting structure for limiting the focal plane adjustment device of the laser receiving lens during the insertion of the mounting section into the detector mounting base.

[0020] Regarding the method for adjusting the focal plane of a laser receiving lens, the present invention, in order to solve the aforementioned technical problem, employs the aforementioned laser receiving lens focal plane adjustment device to adjust the focal plane of the laser receiving lens, comprising the following steps:

[0021] Insert the laser receiving lens focal plane adjustment device into the detector mounting base to simulate the APD avalanche photodetector.

[0022] Use a focus meter to adjust the position of the focal plane so that the image of the focal plane is clearly formed within the central aperture;

[0023] The detector mounting base is translated to adjust the center of the focal plane image to coincide with the center of the central hole;

[0024] Replace the laser receiving lens focal plane adjustment device with the APD avalanche photodetector.

[0025] Compared with related technologies, the receiver focus adjustment device and method of the present invention, which simulates the APD avalanche photodetector for receiver focus adjustment, can effectively avoid the impact of excessively large front aperture on adjustment accuracy, ensure that the focus of the receiving system falls on the photosensitive surface of the detector, maximize the detection capability of the light signal, thereby improving the laser ranging and illumination receiving capability, and has good versatility. Attached Figure Description

[0026] Figure 1 This is a structural diagram of a receiving system according to an embodiment of the present invention;

[0027] Figure 2 This is a perspective view of an APD avalanche photodetector according to an embodiment of the present invention;

[0028] Figure 3 This is a cross-sectional view of an APD avalanche photodetector according to an embodiment of the present invention;

[0029] Figure 4 This is a perspective view of a laser receiving lens focal plane adjustment device according to an embodiment of the present invention;

[0030] Figure 5 This is a cross-sectional view of a laser receiving lens focal plane adjustment device according to an embodiment of the present invention;

[0031] Figure 6 This is a flowchart of a laser receiving lens focal plane adjustment method according to an embodiment of the present invention;

[0032] Figure 7 This is a rendering of a focal plane image according to an embodiment of the present invention.

[0033] Figure label:

[0034] Receiver optical lens group 1; detector mounting base 2; detector photosensitive surface 3; aperture 4; cylindrical body 5; mounting section 51; optical path 6; central aperture 7; limiting structure 8. Detailed Implementation

[0035] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the present invention will be described in detail below with reference to the accompanying drawings and preferred embodiments.

[0036] The steps described in the specification and the flowcharts in the accompanying drawings of this invention are not necessarily to be strictly followed according to the step numbers; the execution order of the steps can be changed. Furthermore, certain steps can be omitted, multiple steps can be combined into one step, and / or one step can be broken down into multiple steps.

[0037] Please see Figure 1 ,like Figure 1 As shown, the receiving mirror optical assembly 1 is connected to the detector mounting base 2, and the detector is mounted on the detector mounting base 2. The receiving mirror optical assembly 1 focuses the received parallel light at the focal point. The detector mounting base 2 is installed between the focusing optical paths. The detector is assembled at the focal point of the receiving mirror optical assembly 1. The detector mounting base 2 is designed with an aperture 4. In order to meet the light transmission requirements, the aperture 4 is usually large, with a diameter of about φ2mm.

[0038] Please see Figure 2-3 ,like Figure 2-3 As shown, the APD avalanche photodetector includes a metal casing with a glass window. The photosensitive surface 3 of the APD avalanche photodetector is encapsulated inside the detector, with a diameter of approximately φ0.2mm. The distance between the photosensitive surface 3 and the glass window is D = 1.6±0.1mm. The thickness of the glass window is 0.8±0.02mm, and the refractive index n = 1.47. Based on the refractive index calculation of the laser wavelength, the distance should be reduced by 0.2mm, resulting in a distance of D = 1.4mm±0.1mm after refraction.

[0039] Please see Figure 4-5 ,like Figure 4-5As shown, to solve the above-mentioned technical problems, the present invention proposes a laser receiving lens focal plane adjustment device to simulate an APD avalanche photodetector. This laser receiving lens focal plane adjustment device includes a cylindrical body 5, which includes a mounting section 51 that mates with and connects to a detector mounting base 2. The outer diameter of the mounting section 51 is inserted into the detector mounting base 2. The mounting section 51 includes a limiting structure 8 for limiting its position during insertion into the detector mounting base 2. An optical path 6 is formed along the axis of the cylindrical body 5. One end of the optical path 6 extends to a predetermined distance from the end face of the cylindrical body 5 near the mounting section 51, and the other end penetrates the cylindrical body 5. The cylindrical body 5 is located near... A central aperture 7 is provided at the center of the end face of one end of the mounting section 51. The central aperture 7 is connected to the optical path 6. The diameter of the central aperture 7 gradually decreases from the end face of the cylindrical body 5 near the mounting section 51 to the bottom surface of the optical path 6, forming a conical structure. This allows the laser beam to be focused when passing through the central aperture 7, improving the quality of the beam. The included angle formed by the axial section of the central aperture 7 is 118 degrees. This angle setting allows the laser beam to be scattered at a certain angle after passing through the central aperture 7, making it easier for the APD avalanche photodetector to receive and convert it into an electrical signal. The shape and position dimensions of the end of the central aperture 7 near the bottom surface of the optical path 6 are consistent with the shape and position dimensions of the photosensitive surface of the detector.

[0040] In the specific implementation process, considering the packaging size and technical requirements of the APD avalanche photodetector, a laser receiving lens focal plane adjustment device was designed to simulate the debugging of the APD avalanche photodetector. To ensure concentricity, the outer diameter of the laser receiving lens focal plane adjustment device must match the mounting base of the APD avalanche photodetector, using a mating method. The refractive index of the glass window mirror of the APD avalanche photodetector for a specific wavelength is calculated, and the distance from the central aperture 7 to the end face is 1.4mm. The diameter of the end of the central aperture 7 near the bottom surface of the optical path 6 is the same as the size of the photosensitive surface of the detector, which is φ0.2mm. The relative position of the end of the central aperture 7 near the bottom surface of the optical path 6 in the cylindrical body 5 is consistent with the relative position of the photosensitive surface of the detector within the APD avalanche photodetector. This laser receiving lens focal plane adjustment device simulates the APD avalanche photodetector, improving the accuracy of laser ranging and detection.

[0041] Please see Figure 6 ,like Figure 6 As shown, to solve the above-mentioned technical problems, the present invention uses the aforementioned laser receiving lens focal plane adjustment device for focal plane adjustment, including the following steps:

[0042] S100: Insert the laser receiving lens focal plane adjustment device into the detector mounting base to simulate the APD avalanche photodetector.

[0043] By inserting the laser receiving lens focal plane adjustment device into the detector mounting base 2, the position and function of the APD avalanche photodetector are simulated, providing a reference for subsequent focal plane adjustment.

[0044] The S200 uses a focus meter to adjust the position of the focal plane so that the image of the focal plane is clearly formed within the central pinhole.

[0045] Please see Figure 7 ,like Figure 7 As shown, the focal plane image is usually a cross shape. By adjusting the focus meter, the focal plane image is made clear within the central aperture 7, that is, the cross-shaped focal plane image can be clearly observed, ensuring that the laser beam can be accurately focused.

[0046] S300, translation detector mounting base, adjusts the center of the focal plane image to coincide with the center of the central aperture.

[0047] By translating the detector mounting base 2, the intersection center of the cross-shaped focal plane image is adjusted to coincide with the center of the central aperture 7. This step can be easily determined by visual observation to ensure that the focal plane image is in the center position, effectively preventing offset and ensuring that the laser beam can be accurately focused on the photosensitive surface of the APD avalanche photodetector, thereby improving the accuracy of detection and ranging.

[0048] The S400 replaces the laser receiver lens focal plane adjustment device with an APD avalanche photodetector.

[0049] After replacing the laser receiver lens focal plane adjustment device with an APD avalanche photodetector, the receiving system can be put into use for actual laser ranging and detection tasks.

[0050] Compared with related technologies, using the receiver focus adjustment device of this invention to simulate the APD avalanche photodetector for receiver focus adjustment can effectively avoid the front aperture 4 being too large and affecting the adjustment accuracy. It can ensure that the focus of the receiving system falls on the φ0.2mm photosensitive surface of the detector, thereby maximizing the detection capability of the light signal and improving the laser ranging and illumination receiving capability.

[0051] Currently, in the field of laser ranging and illumination, APD avalanche photodetectors are used for laser wavelengths of 800–1800 nm. Whether it is an imported device such as the C30659 series or a domestic device such as the GD6510Y, the package size of the device is basically the same. Therefore, the receiving mirror focus adjustment device and method of the present invention have good versatility.

[0052] According to experimental data, the focal plane adjustment device of the present invention was used to adjust the focal plane of 50 receiving systems and to verify the performance on a laser ranging device, with a pass rate of 100%.

[0053] Through the description of specific embodiments, a more in-depth and specific understanding should be gained of the technical means and effects adopted by the present invention to achieve the intended purpose. However, the accompanying drawings are only provided for reference and illustration and are not intended to limit the present invention.

Claims

1. A laser receiving lens focal plane adjustment device, characterized in that, The laser receiving lens focal plane adjustment device is used to simulate the APD avalanche photodetector. The laser receiving lens focal plane adjustment device includes a cylindrical body, the cylindrical body including a mounting section that is connected to and cooperates with the detector mounting base; the mounting section is inserted into the detector mounting base; the mounting section includes a limiting structure for limiting the laser receiving lens focal plane adjustment device during the insertion of the mounting section into the detector mounting base; A light path is provided at the center of the cylindrical body. One end of the light path extends to a set distance from the end face of the cylindrical body near the mounting section, and the other end passes through the cylindrical body. A central hole is provided at the center of the end face of the cylindrical body near the mounting section, and the central hole is connected to the optical path; The diameter of the central hole gradually decreases from the end face of the cylindrical body near the mounting section to the bottom surface of the light path, forming a conical structure; The dimensions of the central aperture near the bottom of the optical path are consistent with the dimensions of the detector's photosensitive surface.

2. The laser receiving lens focal plane adjustment device according to claim 1, characterized in that, The included angle formed by the axial section of the central hole is 118 degrees.

3. The laser receiving lens focal plane adjustment device according to claim 1, characterized in that, The diameter of the central aperture near the bottom of the optical path is 0.2 mm.

4. The laser receiving lens focal plane adjustment device according to claim 1, characterized in that, One end of the light path extends to an end face 1.4 mm away from the end of the cylindrical body near the mounting section.

5. The laser receiving lens focal plane adjustment device according to any one of claims 1-4, characterized in that, The width of the light path is greater than the maximum diameter of the central aperture.

6. A method for adjusting the focal plane of a laser receiving lens, characterized in that, Adjusting the focal plane of a laser receiving lens using the laser receiving lens focal plane adjustment device as described in any one of claims 1-5 includes the following steps: Insert the laser receiving lens focal plane adjustment device into the detector mounting base to simulate the APD avalanche photodetector. Use a focus meter to adjust the position of the focal plane so that the image of the focal plane is clearly formed within the central aperture; The detector mounting base is translated to adjust the center of the focal plane image to coincide with the center of the central hole; Replace the laser receiving lens focal plane adjustment device with the APD avalanche photodetector.

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