LiDAR uses a photoelectric conversion and beam combining device that receives multiple echo signals of the same type.

Abstract

This invention relates to a photoelectric conversion and beam combining device for multiple-channel reception of the same echo optical signal in lidar. The device includes: a sealed box, a single-photon detector, and multiple echo signal receiving lines. The multiple echo signal receiving lines receive the same echo optical signal, process the echo signal, and then transmit the processed optical signal to the single-photon detector. All echo signal lines are housed in the sealed box. Each echo signal receiving line includes: an echo signal fiber, a collimating and focusing lens group, and a narrowband filter. The echo signal fiber receives the echo optical signal. The collimating and focusing lens group includes a collimating lens and a focusing lens. The collimating lens shapes the optical signal into parallel light. The focusing lens focuses the parallel light. The narrowband filter filters out stray light and atmospheric background light from the optical signal. This invention simplifies the optical receiving system components of lidar, reduces system cost, and minimizes signal errors.

Description

Technical Field

[0001] This invention relates to the field of lidar detection technology, and more particularly to an optical receiving device, specifically a photoelectric conversion and beam combining device for lidar to receive multiple echo light signals of the same type. Background Technology

[0002] 1. Atmospheric sounding lidar, due to the high brightness and high collimation of lasers, possesses high spatiotemporal resolution and can detect various atmospheric components. Atmospheric sounding lidar mainly consists of a laser emitting system, an optical receiving and detection system, and a signal acquisition and analysis system. The core equipment of the laser emitting system is various types of lasers or combinations of multiple lasers used to generate atmospheric sounding lasers. The core equipment of the optical receiving and detection system is a telescope system; the telescope can have different designs and apertures that vary depending on requirements, used to receive echo light signals. The core equipment of the signal acquisition and analysis system is a photoelectric conversion control device and a photon counting and acquisition device, used to convert the extremely weak echo photon signals received by the optical receiving and detection system into electrical signals, and to perform high-speed single-photon signal counting, acquisition, and storage.

[0003] 2. Early lidar optical receiving telescopes, if using a single telescope to receive multiple signal lights, employed optical beam splitting in their back-mirror systems. This involved using beam splitters to separate light of different wavelengths before they entered their respective photoelectric conversion systems. With the development of fiber optic technology, receiving telescopes began using optical fibers to receive echo signals. When dealing with multiple echo signals, placing the fiber at the telescope's focal point and utilizing fiber optic focal plane array beam splitting technology allows each wavelength of light to be collected separately and fed into its respective fiber, then into its respective back-mirror system. This avoids the losses caused by the echo signal passing through beam splitters multiple times, significantly simplifies the optical path of the receiving system, and reduces the amount of adjustment required.

[0004] 3. No reports have been found regarding multiple receiving telescopes receiving the same echo signal. A possible approach is to use a single telescope receiving one signal, where the received signal undergoes preliminary signal processing before being fed into a single-photon detector and finally collected and stored. However, this system requires multiple receiving telescopes and a dedicated receiving system, resulting in numerous hardware components and expensive single-photon detectors, leading to high overall costs. Furthermore, since the echo signals are collected and stored by separate single-photon counters, data analysis requires retrieving data from each individual telescope for inversion calculations, complicating the process. Additionally, the performance of each single-photon detector is not guaranteed to be completely consistent due to factors such as spectral responsivity, linearity, pulse stacking error, dark current noise, and quantum efficiency. This can affect the signal-to-noise ratio and introduce errors into data analysis. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems in the prior art where each receiving telescope requires a separate back-mirror receiving system, resulting in numerous hardware devices, high total cost, complex data analysis process, and large detection signal errors. This invention proposes a back-mirror optical path receiving device that allows multiple receiving telescope systems to receive the same signal, specifically a photoelectric conversion and beam combining device for laser radar that receives the same echo light signal from multiple sources.

[0006] This invention proposes a photoelectric conversion and beam combining device for lidar that receives multiple echo light signals of the same type. The device includes a single-photon detector 7 and multiple echo signal receiving lines. The multiple echo signal receiving lines receive the same echo light signal, process the received echo light signal, and then transmit the processed signal to the single-photon detector 7.

[0007] As one of the improvements to the above technical solution, the echo signal receiving line includes: an echo signal optical fiber 1, a collimating focusing lens group 6, and a narrowband filter 5;

[0008] The echo signal fiber 1 is used to receive the echo optical signal;

[0009] The collimating and focusing lens group 6 includes a collimating lens and a focusing lens; the collimating lens is used to shape the optical signal in the echo signal fiber 1 into parallel light; the focusing lens is used to focus the parallel light.

[0010] The narrowband filter 5 is used to filter out stray light and atmospheric background light in the optical signal.

[0011] As an improvement to the above technical solution, the beam combining device further includes a sealed box 8; the plurality of echo signal receiving lines are all disposed in the sealed box 8.

[0012] As one of the improvements to the above technical solution, the sealed box 8 is in the shape of a frustum; the shape of the frustum is: a frustum of a cylinder or a frustum of a prism.

[0013] As one of the improvements to the above technical solution, the sealed box 8 includes an optical fiber input end panel, a photomultiplier tube receiving end panel, and a side panel.

[0014] The fiber optic input end panel has multiple small holes for the echo signal fiber 1 to extend into the sealed box 8; each small hole is provided with a telescopic sealing ring to wrap around the interface between the echo signal fiber 1 and the small hole to ensure the sealing of the sealed box 8.

[0015] The photomultiplier tube receiver panel has a small hole with threads on the inner wall of the hole; the single-photon detector 7 is threaded onto the photomultiplier tube receiver panel of the sealed box 8; a telescopic sealing ring is provided on the outside of the small hole to wrap around the interface between the single-photon detector 7 and the small hole to ensure the sealing of the sealed box 8.

[0016] As an improvement to the above technical solution, both the inner and outer surfaces of the sealed box 8 are treated with frosted black oxidation to prevent stray light from being reflected onto the detection end face of the single-photon detector.

[0017] As an improvement to the above technical solution, the sealed box 8 is provided with a lens barrel 3 inside. The lens barrel 3 has threads inside for installing and fixing the narrow band filter 5 and the collimating focusing lens group 6. One end of the lens barrel 3 is provided with an optical fiber interface, which is connected to the echo signal optical fiber 1 that extends into the sealed box 8. The other end is a through hole, which allows the processed optical signal to pass through.

[0018] As an improvement to the above technical solution, the narrowband filter 5 is disposed between or outside the collimating lens and the focusing lens of the collimating and focusing lens group 6.

[0019] As an improvement to the above technical solution, a three-dimensional direction adjustment bracket 2 is provided on the inner wall of the side panel of the sealed box 8, and a lens barrel fixing bracket 4 is provided on the three-dimensional direction adjustment bracket 2; the lens barrel fixing bracket 4 is used to install and fix the lens barrel 3; the three-dimensional direction adjustment bracket 2 is used to adjust the direction of the lens barrel 3.

[0020] As an improvement to the above technical solution, when adjusting the direction of the lens barrel 3, the three-dimensional direction adjustment bracket 2 uses the generatrix of the fixed point sealed box as a reference to adjust the lens barrel 3 up and down along the generatrix direction, adjust the tilt angle relative to the generatrix direction, and / or adjust the tilt angle relative to the height line direction of the sealed box 8; the fixed point is the connection point between the three-dimensional direction adjustment bracket 2 and the sealed box 8.

[0021] This invention proposes a back-mirror optical path receiving device for receiving the same signal using multiple receiving telescope systems; the advantages of this invention compared to existing technologies are:

[0022] 1. It simplifies the optical receiving system components of lidar, reducing system costs;

[0023] 2. It reduces signal errors caused by using multiple detectors. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the photoelectric conversion and beam combining device for multiple-channel reception of the same echo light signal for lidar proposed in this invention.

[0025] Figure 2 This is a schematic diagram of the beam combining device for photoelectric conversion of four-channel receiving signals in a calcium atom lidar, along with its experimental debugging components.

[0026] Attached Figure Labels

[0027] 1. Echo signal fiber optic cable; 2. Three-dimensional orientation adjustment bracket; 3. Lens tube.

[0028] 4. Lens barrel holder; 5. Narrow band filter; 6. Collimating and focusing lens group.

[0029] 7. Single-photon detector; 8. Sealed box; 9. Optical receiving telescope

[0030] 10. Fiber optic coupler; 11. Calcium atom laser emission system; 12. High-power laser reflector.

[0031] 13. Laser beam emission system; 14. Data acquisition and analysis system Detailed Implementation

[0032] The technical solutions provided by the present invention will be further illustrated below with reference to the embodiments.

[0033] This invention provides a photoelectric conversion and beam combining device for multiple-channel reception of the same echo optical signal for lidar, which can be used in a receiving device that receives at least one echo signal. The lidar system includes a laser emitting system, an optical receiving system, and a data acquisition and processing system.

[0034] like Figure 1The diagram shows a schematic of the photoelectric conversion and beam combining device for receiving multiple echo signals of the same type in lidar, as proposed in this invention. This device is a component of the lidar optical receiving system and mainly includes: an echo signal fiber 1, and an echo signal receiving fiber 1 for the telescope (not all of which are shown in the diagram; ellipses indicate echo signal fibers 1 not fully displayed), a three-dimensional orientation adjustment bracket 2, a lens barrel 3, a lens barrel fixing frame 4, a narrowband filter 5, a collimating and focusing lens group 6, a single-photon detector 7, and a sealed box 8. The telescope receives echo signals via an optical fiber 1, which passes through a frustum-shaped sealed box 8 and is installed at one end of the telescope tube 3. This fiber is used to send the optical signal received by the lidar optical receiving system into the collimating and focusing lens group 6 inside the telescope tube 3. The telescope tube mounting bracket 4 mounts the telescope tube 3 onto a three-dimensional direction adjustment bracket 2 to adjust the direction of the focused beam. The collimating and focusing lens group 6 is placed inside the telescope tube 3. The collimating lens shapes the light output from the optical fiber into parallel light, and the focusing lens focuses this parallel light. A narrowband filter 5 is placed inside the collimating and focusing lens group to filter out stray light and atmospheric background light in the signal light received by the optical fiber. A single-photon detector 7 is used to receive the optical signal passing through the telescope tube 3. The frustum-shaped sealed box 8 serves to seal the area, prevent stray light, and protect the detection end face of the single-photon detector 7.

[0035] The components of the device proposed in this invention have the following functions or processes:

[0036] 1. The inside and outside of the sealed box 8 are treated with frosted black oxidation;

[0037] 2. The sealed box 8 is not a single piece; the upper and lower panels can be disassembled. The upper panel has multiple small holes, and the outside of the small holes has a telescopic sealing ring. The lower panel has one small hole, the inner wall of which has threads, and the outside of which has a telescopic sealing ring.

[0038] 3. One end of the echo signal fiber 1 is connected to the telescope in the lidar receiving system and placed at the focal point of the telescope; the other end extends into the box through a small hole on the sealed box 8.

[0039] 4. The three-dimensional direction adjustment bracket 2 is fixed on the sealed box 8, which can finely adjust the direction of the lens tube 3. With the generatrix of the fixed point sealed box 8 as the reference, it can be adjusted up and down along the generatrix direction, the tilt angle relative to the generatrix direction, and the tilt angle relative to the height line direction of the sealed box 8.

[0040] 5. The lens barrel 3 is connected and fixed to the three-dimensional direction adjustment bracket 2 via the lens barrel fixing bracket 4;

[0041] 6. One end of the lens tube 3 is equipped with an optical fiber interface, which is connected to the echo signal optical fiber 1 that extends into the circular hole on the sealed box 8; the other end is a through hole, which allows light to pass through.

[0042] 7. The lens barrel 3 has internal threads, which can be used to fix the lens with a retaining ring;

[0043] 8. The collimating and focusing lens group 6 is installed inside the lens barrel 3 and fixed with a retaining ring;

[0044] 9. The narrow-band filter 5 is installed inside the lens barrel 3, placed between or outside the two collimating focusing lenses, and fixed with a retaining ring;

[0045] 10. The single-photon detector 7 is installed on the photomultiplier tube receiving end panel of the sealed box 8 and is fixed to the photomultiplier tube receiving end panel by threads;

[0046] like Figure 2 The diagram shown is a schematic of the connection between the present invention and the telescope receiving system in an embodiment. Specifically, it is a schematic diagram of the beam combining device for receiving echo light signals from four channels in a calcium atom lidar, and its experimental debugging components. The specific implementation method is as follows:

[0047] 1. The calcium atom lidar system comprises a laser emitting system, an optical receiving system, and a data acquisition and analysis system. The beam combining device (in this invention) that receives four echo signals is part of the optical receiving system.

[0048] 2. The calcium atom lidar system includes: 1. 4 echo signal optical fibers; 2. 4 three-dimensional direction adjustment brackets; 3. 4 lens tubes; 4. 4 lens tube fixing brackets; 4. 4 narrowband filters; 5. 4 collimating and focusing lens groups; 6. single photon detector; 7. frustum-shaped sealed box; 8. 4 optical receiving telescopes; 9. 4 fiber optic couplers; 10. calcium atom laser emission system; 11. high-power laser reflector; 12. and data acquisition and analysis system; 14.

[0049] 3. The laser emission system of the calcium atom lidar outputs a laser beam with a wavelength of 422.7nm, which is emitted into the sky through the high-power laser reflector 12. The propagation path of the emitted laser beam 13 is shown in the figure.

[0050] 4. Four optical receiving telescopes 9 receive the resonant echo photons from the calcium atom metal layer;

[0051] 5. Four optical receiving telescopes 9 are coaxial with the transmitting laser beam 13;

[0052] 6. Four fiber optic couplers 10 are respectively installed at the focal points of four optical receiving telescopes 9 to fix the four echo signal fiber optic cables 1 at the corresponding telescope focal points.

[0053] 7. The echo photons received by the four optical receiving telescopes 9 are respectively fed into the four echo signal optical fibers 1;

[0054] 8. The 4-channel echo signal fiber optic cable 1 extends into the box through the round hole on the frustum-shaped sealed box 8 and connects to the lens tube 3.

[0055] 9. The collimating and focusing lens group 6 and the narrow band filter 5 are installed inside the lens barrel 3 and fixed with retaining rings;

[0056] 10. The single-photon detector 7 is installed on the lower panel of the frustum-shaped sealed box 8;

[0057] 11. The data signal line of the single-photon detector 7 is connected to the data acquisition and analysis system 14;

[0058] 12. After all hardware conditions are connected, begin debugging the beam combiner for receiving 4-channel echo optical signals;

[0059] 13. During debugging, each of the four channels should be debugged separately. You can first unplug the fiber from one of the fiber couplers 10, and then shine a weak beam of light into the fiber. By adjusting the knob of the three-dimensional direction adjustment bracket 2, the collimated and focused light signal can be completely incident on the receiving end face of the single-photon detector 7. Note that the single-photon detector 7 does not need to be turned on at this time. After debugging, install this fiber into the fiber coupler 10 of the receiving telescope 9.

[0060] 14. Similarly, debug the beam combiner for the remaining 3 channels of receiving echo optical signals;

[0061] 15. This completes the debugging of the beam combining device for the four-channel echo signal receiver of the calcium atom lidar, and the lidar equipment can be turned on to detect calcium atom metal layers.

[0062] As can be seen from the above detailed description of the present invention, the device proposed by the present invention solves the problem of how to build the back optical path system of multiple receiving telescopes. In particular, for the same received signal, the device is simple and feasible, reduces the system cost, and eliminates the error introduced by correcting the characteristic parameters of multiple photomultiplier tubes. With this device, it is only necessary to correct the characteristic parameter error of one receiving phototube.

[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to the embodiments, those skilled in the art should understand that modifications or equivalent substitutions to the technical solutions of the present invention do not depart from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. An optoelectronic conversion and beam combination device for receiving multiple channels of the same returned optical signal in a lidar, characterized in that, The device includes: a single-photon detector (7) and multiple echo signal receiving lines; the multiple echo signal receiving lines receive the same echo light signal, process the received echo light signal, and then transmit the processed signal to the single-photon detector (7); The echo signal receiving line includes an echo signal optical fiber (1) for receiving echo optical signals; The beam combining device also includes a sealed box (8); the multiple echo signal receiving lines are all set in the sealed box (8); one end of the echo signal optical fiber is connected to the telescope in the lidar receiving system and placed at the focal point of the telescope, and the other end extends into the sealed box. The sealed box (8) is in the shape of a frustum, which is either a frustum or a pyramid, and has a large base and a small base. The sealed box (8) includes an optical fiber input end panel, a photomultiplier tube receiving end panel and a side panel; the optical fiber input end panel is located at the large bottom surface, and the photomultiplier tube receiving end panel is located at the small bottom surface; The sealed box (8) is equipped with multiple mirror tubes (3) corresponding to the multiple echo signal receiving lines. Each mirror tube (3) has an optical fiber interface at one end, which is connected to the echo signal optical fiber (1) that extends into the sealed box (8); the other end is a through hole, which allows the processed optical signal to pass through and be incident on the receiving end face of the single photon detector. The inner wall of the side panel of the sealed box (8) is provided with a three-dimensional direction adjustment bracket (2), and a lens barrel fixing bracket (4) is provided on the three-dimensional direction adjustment bracket (2); the lens barrel fixing bracket (4) is used to install and fix the lens barrel (3); the three-dimensional direction adjustment bracket (2) is used to adjust the direction of the lens barrel (3); When adjusting the direction of the lens barrel (3), the three-dimensional direction adjustment bracket (2) uses the generatrix of the fixed point sealed box as a reference to adjust the lens barrel (3) up and down along the generatrix direction, adjust the tilt angle relative to the generatrix direction, and / or adjust the tilt angle relative to the height line direction of the sealed box (8); the fixed point is the connection point between the three-dimensional direction adjustment bracket (2) and the sealed box (8); The photomultiplier tube receiver panel has a small hole with threads on the inner wall of the hole; the single photon detector (7) is installed on the photomultiplier tube receiver panel of the sealed box (8) by the threads. The fiber optic input end panel has multiple small holes for the echo signal fiber (1) to extend into the sealed box (8); each small hole is provided with a flexible sealing ring to wrap around the interface between the echo signal fiber (1) and the small hole, so as to ensure the sealing of the sealed box (8). The inner and outer surfaces of the sealed box (8) are treated with frosted black oxidation.

2. The photoelectric conversion and beam combination device for receiving multiple same echo light signals in a laser radar according to claim 1, characterized in that, The echo signal receiving line also includes: a collimating focusing lens group (6) and a narrowband filter (5); The collimating and focusing lens group (6) includes a collimating lens and a focusing lens; the collimating lens is used to... The optical signal in the echo signal fiber (1) is shaped into parallel light; the focusing lens is used to focus the parallel light; The narrowband filter (5) is used to filter out stray light and atmospheric background light in the optical signal.

3. The photoelectric conversion and beam combination device for receiving multiple echo light signals of the same kind in a laser radar according to claim 2, characterized by, The lens barrel (3) has internal threads for mounting and fixing the narrow band filter (5) and the collimating focusing lens group (6).

4. The photoelectric conversion and beam combining device for multiple-channel reception of the same echo light signal for lidar according to claim 3, characterized in that, The narrowband filter (5) is disposed between or outside the collimating lens and the focusing lens of the collimating and focusing lens group (6).

Images