Light acquisition circuit, optical time domain reflectometer and laser radar
By introducing a filter module and a current limiting module into the light acquisition circuit, the problem of signal linearity deterioration and signal-to-noise ratio reduction in optical time domain reflectors and lidars is solved, and a higher signal linearity and signal-to-noise ratio are achieved.
Patent Information
- Application Number
- CN202323598341.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-27
- Publication Date
- 2025-03-04
- Estimated Expiration
- 2033-12-27
AI Technical Summary
The existing optical time-domain reflectors and lidars have deteriorated linearity and reduced signal-to-noise ratio during signal acquisition.
An optical acquisition circuit is designed, including a power supply module, a filter module, a current limiting module and a acquisition module. High-frequency noise is filtered out through the filter module, and the current limiting module protects the acquisition module to improve the linearity and signal-to-noise ratio of the signal.
It effectively improves the gain flatness of the light acquisition circuit, improves the linearity of the signal and noise ratio, and solves the problem of signal deterioration and signal-to-noise ratio reduction.
Smart Images
Figure CN222561130U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of light detection, in particular to a light collection circuit, an optical time domain reflectometer and a laser radar. Background Art
[0002] Currently, pulsed light is generally used for measurement and detection in optical time domain reflectometers and lidar products. Since the reflected signal of pulsed light is very weak, the front-end design generally uses APD to receive the optical signal. For existing APD application scenarios, traditional resistor current limiting will cause changes in the APD bias voltage, that is, the APD gain will change, resulting in poor linearity and reducing the signal-to-noise ratio.
[0003] Therefore, it is very important for those skilled in the art to design a light collection circuit, an optical time domain reflectometer and a lidar with high linearity and high signal-to-noise ratio. Utility Model Content
[0004] The technical problem to be solved by the embodiments of the utility model is to provide a light collection circuit, an optical time domain reflectometer and a laser radar with high linearity and high signal-to-noise ratio, so as to solve the problems of poor signal linearity and reduced signal-to-noise ratio in the prior art.
[0005] The utility model discloses a light collection circuit, which is used for collecting and converting light signals. The scheme of the utility model is that the circuit comprises: a power supply module, a filtering module, a current limiting module and a collection module; the power supply module is used for providing a bias voltage, the voltage input end of the filtering module is connected with the voltage output end of the power supply module to filter the bias voltage, the voltage input end of the current limiting module is connected with the voltage output end of the filtering module to receive the filtered bias voltage and limit the current; the voltage input end of the collection module is connected with the voltage output end of the current limiting module to convert photoelectric signals and to amplify the converted electrical signals according to the bias voltage.
[0006] Optionally, the filtering module includes an inductor and a capacitor, the input end of the inductor is connected to the power supply module, the output end of the inductor is connected to the current limiting module, one end of the capacitor is connected to the output end of the inductor, and the other end of the capacitor is grounded.
[0007] Optionally, the current limiting module includes a switch and a sampling resistor, the input end of the switch is connected to the output end of the filtering module, the output end of the switch is connected to one end of the sampling resistor, and the other end of the sampling resistor is connected to the acquisition module.
[0008] Optionally, the current limiting module further includes an operational amplifier, an input end of the operational amplifier is connected to two ends of the sampling resistor, and an output end of the operational amplifier is connected to the switch.
[0009] Optionally, the acquisition module includes a photodiode and a transimpedance amplifier, the cathode of the photodiode is connected to the voltage output end of the current limiting module, and the anode of the photodiode is connected to the transimpedance amplifier.
[0010] Optionally, the optical signal is a pulsed optical signal.
[0011] The utility model also provides an optical time domain reflectometer, which includes the light collection circuit as described above, and also includes a first light transmitter, a first light receiver and a first main controller, wherein the control ends of the first light transmitter and the first light receiver are connected to the first main controller, and the output end of the first light receiver is connected to the light collection circuit.
[0012] Optionally, it also includes a first clock circuit, which is connected to the first main controller.
[0013] The utility model also provides a laser radar, which includes the light collection circuit as described above, and also includes a second light transmitter, a second light receiver, a scanner and a second main controller, the control ends of the second light transmitter, the second light receiver and the scanner are all connected to the second main controller, and the output end of the second light receiver is connected to the light collection circuit.
[0014] Optionally, a second clock circuit is further included, and the second clock circuit is connected to the second main controller.
[0015] Compared with the prior art, the beneficial effect of the light collection circuit provided by the embodiment of the utility model is that: by adding a filtering module and a current limiting module to the light collection circuit, and setting the filtering module at the voltage input end of the current limiting module, the current limiting module can be used to protect the collection module while the filtering module can be used to filter out high-frequency noise. This not only avoids the problem of easy damage to the collection module when the input end is high-power light, but also can effectively improve the gain flatness of the light collection circuit, improve the linearity of the collected signal, and improve the signal-to-noise ratio of the collected signal. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] The technical solution of the utility model will be further described in detail below with reference to the accompanying drawings and embodiments, in which:
[0017] Figure 1 It is a structural schematic diagram of a light collection circuit provided by an embodiment of the utility model;
[0018] Figure 2is a circuit diagram of a light collection circuit provided by an embodiment of the utility model;
[0019] Figure 3 It is a schematic diagram of the structure of the optical time domain reflectometer provided by the embodiment of the utility model;
[0020] Figure 4 It is a schematic diagram of the structure of the laser radar provided in an embodiment of the utility model. DETAILED DESCRIPTION
[0021] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. Now, in conjunction with the accompanying drawings, a preferred embodiment of the present utility model is described in detail.
[0022] like Figure 1 As shown, the utility model provides a specific embodiment of a light collection circuit.
[0023] A light collection circuit for collecting and converting light signals, referring to Figure 1 The light collection circuit includes: a power supply module 11, a filter module 12, a current limiting module 13 and a collection module 14; the voltage input end of the filter module 12 is connected to the voltage output end of the power supply module 11, the voltage input end of the current limiting module 13 is connected to the voltage output end of the filter module 12, and the voltage input end of the collection module 14 is connected to the voltage output end of the current limiting module 13.
[0024] Specifically, refer to Figure 1 The optical acquisition circuit is mainly used for the acquisition and signal conversion of optical signals. The optical signal is an optical pulse signal. In a system that uses pulsed light for measurement and detection, since the reflected signal of the pulsed light signal is very weak, it is necessary to use APD to receive the optical signal in the front-end design of the system. In the APD application scenario, the traditional method is to use a current limiting resistor to limit the current. The current limiting resistor in this method will bring changes to the bias voltage of the APD, that is, the gain of the APD will change, which is easy to cause the linearity to deteriorate, and at the same time will reduce the signal-to-noise ratio of the signal. The optical acquisition circuit in this embodiment can effectively solve these problems.
[0025] The optical collection circuit includes a power module 11, which is mainly used to provide a bias voltage for the collection module 14 to increase the gain of the collection module 14; the bias voltage refers to a constant voltage applied in an electronic device or circuit to enable it to work normally, so that the operating point of the electronic device or circuit is set within a suitable working range to ensure its normal operation and performance. In this embodiment, the bias voltage is provided by the power module 11, so that the collection module 14 can be in a suitable working area to achieve the required amplification, switching K and detection functions, as well as to ensure the performance indicators such as gain, linearity, power consumption and noise during the period.
[0026] The light collection circuit also includes a filter module 12, the voltage input end of the filter module 12 is connected to the power module 11, and the filter module 12 is mainly used to reduce the ripple of the bias voltage provided by the power module 11; wherein, the filter includes a low-pass filter and a high-pass filter, the low-pass filter allows low-frequency signals below the cut-off frequency to pass through, and blocks high-frequency signals above the cut-off frequency, while the high-pass filter allows high-frequency signals above the cut-off frequency to pass through, and blocks low-frequency signals below the cut-off frequency; in this embodiment, the filter module 12 is a low-pass filter, which is used to filter out high-frequency noise to improve the signal-to-noise ratio of the signal.
[0027] The light collection circuit also includes a current limiting module 13, a voltage input end of the current limiting module 13 is connected to a voltage output end of the filter module 12, and a voltage output end of the current limiting module 13 is connected to a voltage input end of the collection circuit, so as to detect the current and take measures to limit the current when the current exceeds a set threshold, thereby protecting the collection module 14 to prevent the electronic components in the collection module 14 from being damaged by excessive current.
[0028] The light collection circuit also includes a collection module 14, the voltage input end of the collection module 14 is connected to the voltage output end of the current limiting module 13, and the collection module 14 is mainly used to receive light signals, convert the light signals into electrical signals, and amplify the converted electrical signals to a desired size and output them.
[0029] In this embodiment, by adding a filtering module and a current limiting module to the light collection circuit, and setting the filtering module at the voltage input end of the current limiting module, the current limiting module can be used to protect the collection module while the filtering module can be used to filter out high-frequency noise. This not only avoids the problem of easy damage to the collection module when the input end is high-power light, but also effectively improves the gain flatness of the light collection circuit, improves the linearity of the collected signal, and improves the signal-to-noise ratio of the collected signal.
[0030] In one embodiment, reference Figure 2 The filtering module 12 includes an inductor L and a capacitor C, the input end of the inductor L is connected to the power module 11, the output end of the inductor L is connected to the current limiting module 13, one end of the capacitor C is connected to the output end of the inductor L, and the other end of the capacitor C is grounded.
[0031] Specifically, refer to Figure 2 The filter module 12 is a low-pass filter module 12, the inductor L provides impedance to high-frequency signals, and the capacitor C provides a path for low-frequency signals, wherein the cut-off frequency can be controlled by adjusting the value of the inductor L and the value of the capacitor C, thereby selecting the frequency range from passing to blocking; the specific values of the inductor L and the capacitor C are set according to actual needs.
[0032] In one embodiment, reference Figure 2 The current limiting module 13 includes a switch K and a sampling resistor R, the input end of the switch K is connected to the output end of the filtering module 12 , the output end of the switch K is connected to one end of the sampling resistor R, and the other end of the sampling resistor R is connected to the acquisition module 14 .
[0033] Specifically, refer to Figure 2 The current limiting module 13 also includes an operational amplifier U, the input end of the operational amplifier U is connected to the two ends of the sampling resistor R, and the output end of the operational amplifier U is connected to the switch K; the current limiting module 13 is mainly used to set the magnitude of the current flowing through the acquisition module 14. By setting the amplification factor of the operational amplifier U and the resistance value of the sampling resistor R, the closing of the switch K can be controlled under corresponding conditions, thereby achieving the purpose of protecting the acquisition module 14.
[0034] In one embodiment, reference Figure 2 The acquisition module 14 includes a photodiode APD and a transimpedance amplifier TIA. The cathode of the photodiode APD is connected to the voltage output end of the current limiting module 13, and the anode of the photodiode APD is connected to the transimpedance amplifier TIA.
[0035] Specifically, refer to Figure 2 The photodiode APD works based on the principle of the photoelectric effect. When light shines on the photodiode APD, the generated photons will excite the electrons of the semiconductor, thereby generating current to realize the conversion of light energy into electrical energy; the transimpedance amplifier TIA is mainly used to convert weak current signals into measurable voltage signals and provide control of the amplification factor; the acquisition module 14 can convert the received weak light signal into an electrical signal, and the electrical signal can be amplified to the actual required size.
[0036] like Figure 3 As shown, the utility model also provides a specific embodiment of an optical time domain reflectometer.
[0037] An optical time domain reflectometer, reference Figure 3 The optical time domain reflectometer includes the above-mentioned light collection circuit 40, and also includes a first light transmitter 10, a first light receiver 20 and a first main controller 30. The control ends of the first light transmitter 10 and the first light receiver 20 are connected to the first main controller 30, and the output end of the first light receiver 20 is connected to the light collection circuit 40.
[0038] Specifically, refer to Figure 3 ,Optical Time Domain Reflectometer is an instrument used to measure the reflection and attenuation characteristics of optical fiber transmission links. It analyzes the reflection, attenuation and fault location in the optical fiber by sending a pulsed light signal into the optical fiber and measuring the time and intensity changes of the light signal propagating in the optical fiber.
[0039] Furthermore, the first optical transmitter 10 is mainly used to send pulsed light signals, that is, to generate pulsed light signals through a light source and inject them into the optical fiber to be tested; the first optical receiver 20 is mainly used to receive reflected signals. When the pulsed light signal propagates in the optical fiber, it will be reflected by the reflection points in the optical fiber (such as connectors, attenuators or fault points, etc.). The first optical receiver 20 can receive these reflected signals. The optical collection circuit 40 is mainly used to convert the reflected light signal received by the first optical receiver 20 into an electrical signal, and amplify the weak electrical signal to the actual required size.
[0040] In one embodiment, reference Figure 3 , also includes a first clock circuit 50, and the first clock circuit 50 is connected to the first main controller 30.
[0041] Specifically, the first clock circuit 50 is mainly used to generate a stable timing signal for synchronizing and controlling various functional modules in the optical time domain reflectometer.
[0042] like Figure 4 As shown, the utility model also provides a specific embodiment of a laser radar.
[0043] A laser radar, reference Figure 4 The laser radar includes the above-mentioned light collection circuit 40, and also includes a second light transmitter 60, a second light receiver 70, a scanner 80 and a second main controller 90. The control ends of the second light transmitter 60, the second light receiver 70 and the scanner 80 are all connected to the second main controller 90, and the output end of the second light receiver 70 is connected to the light collection circuit.
[0044] Specifically, refer to Figure 4 LiDAR is a technology that uses laser beams for long-distance ranging and three-dimensional space perception. The second light transmitter 60 is used to emit a laser beam, specifically a short-pulse laser beam. The wavelength of the laser beam is usually in the infrared or near-infrared range so that it can propagate farther in the atmosphere; the scanner 80 is mainly used to scan the target object so that the emitted laser beam scans the target object; the second light receiver 70 is mainly used to receive the reflected signal. When the emitted laser beam is irradiated on the target object, a part of it will be reflected back by the target object and received by the second light receiver 70; the light collection circuit is mainly used to convert and amplify the received reflected light signal.
[0045] In one embodiment, reference Figure 4 , also includes a second clock circuit 100, and the second clock circuit 100 is connected to the second main controller 90.
[0046] Specifically, refer to Figure 4The second clock circuit 100 is mainly used to generate a stable timing signal for synchronizing and controlling various functional modules in the laser radar.
[0047] It should be understood that the above embodiments are only used to illustrate the technical solutions of the present utility model rather than to limit it. For those skilled in the art, the technical solutions described in the above embodiments can be modified, or some of the technical features therein can be replaced by equivalents; and all these modifications and replacements should fall within the scope of protection of the claims attached to the present utility model.
Claims
1. A light collection circuit for collecting and converting light signals, characterized in that: include: Power module, filter module, current limiting module and acquisition module; The power module is used to provide a bias voltage, the voltage input end of the filter module is connected to the voltage output end of the power module to filter the bias voltage, and the voltage input end of the current limiting module is connected to the voltage output end of the filter module to receive the filtered bias voltage and limit the current; The voltage input end of the acquisition module is connected to the voltage output end of the current limiting module for photoelectric signal conversion and for amplifying the converted electrical signal according to the bias voltage.
2. The light collection circuit according to claim 1, characterized in that: The filtering module includes an inductor and a capacitor, the input end of the inductor is connected to the power module, the output end of the inductor is connected to the current limiting module, one end of the capacitor is connected to the output end of the inductor, and the other end of the capacitor is grounded.
3. The light collection circuit according to claim 1, characterized in that: The current limiting module includes a switch and a sampling resistor, the input end of the switch is connected to the output end of the filtering module, the output end of the switch is connected to one end of the sampling resistor, and the other end of the sampling resistor is connected to the acquisition module.
4. The light collection circuit according to claim 3, characterized in that: The current limiting module further includes an operational amplifier, an input end of the operational amplifier is connected to two ends of the sampling resistor, and an output end of the operational amplifier is connected to the switch.
5. The light collection circuit according to claim 1, characterized in that: The acquisition module includes a photodiode and a transimpedance amplifier, the cathode of the photodiode is connected to the voltage output end of the current limiting module, and the anode of the photodiode is connected to the transimpedance amplifier.
6. The light collection circuit according to claim 1, characterized in that: The optical signal is a pulsed optical signal.
7. An optical time domain reflectometer, characterized in that: It includes the light collection circuit as described in any one of claims 1-6, and also includes a first light transmitter, a first light receiver and a first main controller, the control ends of the first light transmitter and the first light receiver are connected to the first main controller, and the output end of the first light receiver is connected to the light collection circuit.
8. The optical time domain reflectometer according to claim 7, characterized in that: It also includes a first clock circuit, which is connected to the first main controller.
9. A laser radar, characterized in that: It includes the light collection circuit as described in any one of claims 1-6, and also includes a second light transmitter, a second light receiver, a scanner and a second main controller, the control ends of the second light transmitter, the second light receiver and the scanner are all connected to the second main controller, and the output end of the second light receiver is connected to the light collection circuit.
10. The laser radar according to claim 9, characterized in that: It also includes a second clock circuit, which is connected to the second main controller.