A method and system for improving the near-range detection capability of a laser range finder

Abstract

The application discloses a method and system for improving the close-range detection capability of a laser range finder, and comprises the following steps: a laser range finder emits a measuring laser to a target, receives a returned light signal, and acquires a first signal energy; it is judged whether the first signal energy is greater than a preset threshold; if yes, the next step is executed; the sensitivity of a photoelectric detection component is reduced, so that the photoelectric detection component is in a low sensitivity state, and the target is measured; it is judged whether the returned light signal is a valid signal; if yes, the sensitivity of the photoelectric detection component is improved. The application actively reduces the sensitivity of the photoelectric detection component by intelligently judging a close-range strong signal scene, suppresses a stray echo from a source of signal generation, and makes the energy of the stray echo lower than a detection threshold, so that false signal generation is fundamentally avoided; after the stray light is suppressed, a secondary energy judgment is performed, the valid target signal is ensured not to be excessively suppressed, the adaptive closed-loop adjustment of the sensitivity is realized, and the requirements of suppressing interference and keeping signal detection capability are met.

Description

Technical Field

[0001] This invention belongs to the field of laser ranging technology, specifically relating to a method and system for improving the short-range detection capability of laser rangefinders. Background Technology

[0002] Military laser rangefinders often employ the time-of-flight method, calculating the distance L between the laser rangefinder and the object by precisely measuring the time interval between the emitted and received laser signals. Figure 1 As shown: in, , These represent the times of laser signal transmission and reception, respectively. It is the speed of light.

[0003] To improve ranging capabilities, high-sensitivity photoelectric detection components such as APDs, SPADs, or electron multiplier tubes are typically selected to convert the weak returned light signal into an electrical signal. This signal is then amplified through multiple stages to extract the effective electrical signal. Figure 2 As shown.

[0004] Laser rangefinders also need to detect close-range targets. The energy of the received return light signal is inversely proportional to the square of the target distance. For example, if the return light energy of a target at 1 km is E, then the return light energy of a target at 1 m is 10. 6 E, dynamic range reaches 60dB. When measuring close-range targets, the returned light energy is relatively strong, the current is relatively large, which easily causes signal oscillation, and the oscillation duration is relatively long, reaching the microsecond level, affecting the ranging resolution of the rangefinder. Therefore, laser rangefinder receiving circuits often employ multi-channel receiving signal identification circuits, with low-amplification circuits responsible for close-range target identification. Figure 2 The signal recognition circuit 2 in the middle), the high amplification circuit is responsible for long-distance recognition ( Figure 2 In the signal recognition circuit 1), the dynamic range of the returned optical signal handled by each part of the circuit will decrease proportionally: ① When measuring a close-range target, the returned light energy is strong. When signal oscillation occurs in signal recognition circuit 1, the signal is amplified normally in signal recognition circuit 2. ② When measuring distant targets, the returned light energy is weak, and the returned signal in the signal recognition circuit 2 is relatively small and cannot be recognized. However, due to the large amplification factor, the signal recognition circuit 1 detects the returned light signal and there is no signal oscillation.

[0005] This approach effectively balances both long-range and short-range signal detection, enhancing short-range ranging capabilities.

[0006] However, the above solution has a risk of failure in long-range laser rangefinders. To increase the detection range, long-range laser rangefinders have larger receiving lens apertures, resulting in greater received echo energy, including scattered echoes. These scattered echoes can also cause the photoelectric detection components to generate effective outputs. The signal recognition circuit 2 then receives not only the target signal but also the scattered echo signal, which is a false signal. This can lead to target ranging failure or reduced accuracy, requiring further measures to reduce the impact of scattered echoes. Summary of the Invention

[0007] To address the problems in the prior art, the present invention aims to provide a method and system for improving the short-range detection capability of laser rangefinders.

[0008] To achieve the above objectives and technical effects, the technical solution adopted by this invention is as follows: A method for improving the short-range detection capability of a laser rangefinder includes the following steps: (1) The laser rangefinder emits a measuring laser towards the target, receives the returned light signal, and obtains the first signal energy. ; (2) Judgment ,in The minimum energy value at which the scattered echo signal can be mistakenly identified as a valid returned optical signal: if yes, then proceed to step (3); otherwise, maintain the current working state. (3) Reduce the sensitivity of the photoelectric detection component, so that < ; (4) When the photoelectric detection component is in a low-sensitivity state, the target is ranged and the energy of the second signal is recorded. ; (5) Judgment If yes, then increase the sensitivity of the photoelectric detection component; if no, then maintain the photoelectric detection component in a low-sensitivity state. (6) Repeat the above steps.

[0009] Furthermore, in step (1), the first signal energy The pulse width of the electrical signal generated after the return optical signal is converted by photoelectric conversion is used to characterize the signal. The larger the pulse width, the greater the signal energy value.

[0010] Furthermore, in step (1), the first signal energy Obtained through a low amplification circuit.

[0011] Furthermore, the sensitivity of the photodetector can be reduced or increased by adjusting the operating bias voltage of the photodetector.

[0012] Furthermore, in step (3), the photoelectric detection component is an APD, and the reverse bias voltage of the APD is changed from high voltage. Reduced to low pressure To reduce sensitivity.

[0013] Furthermore, in step (5), the reverse bias of the APD is changed from low voltage. Restore to high voltage To improve sensitivity.

[0014] This invention also discloses a system for improving the short-range detection capability of a laser rangefinder, employing a method described above for improving the short-range detection capability of a laser rangefinder, including: The laser emitting module is used to emit detection lasers; A photoelectric detection component, used to receive returned optical signals and convert them into electrical signals; The signal processing module includes at least a low amplification circuit for processing electrical signals to obtain signal energy values. A sensitivity control module, connected to the photoelectric detection component, is used to adjust the sensitivity of the photoelectric detection component according to the output of the signal processing module; The sensitivity control module is configured as follows: when Furthermore, when the target distance is close, the photoelectric detection component is controlled to reduce its sensitivity; After performing ranging under low sensitivity conditions, if Then, the sensitivity of the photoelectric detection component is increased.

[0015] Furthermore, the photoelectric detection module includes an APD, and the sensitivity control module changes the sensitivity by adjusting the reverse bias voltage applied to the APD.

[0016] Furthermore, by changing the reverse bias of the APD from high voltage... Reduced to low pressure To reduce sensitivity.

[0017] Furthermore, by changing the reverse bias of the APD from low voltage... Restore to high voltage To improve sensitivity.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: 1) Precise suppression of stray light: This invention does not simply perform gain switching, but actively reduces the response sensitivity of the photoelectric detection component by intelligently judging the strong signal scene at close range, suppressing stray echoes from the source of signal generation, so that their energy is lower than the detection threshold, and fundamentally avoiding the generation of false signals; 2) Adaptive sensitivity adjustment: After suppressing stray light, secondary energy judgment is used to ensure that the effective target signal is not over-suppressed, thus realizing adaptive closed-loop adjustment of sensitivity, which takes into account both the need to suppress interference and maintain signal detection capability. 3) Strong compatibility: This invention can be seamlessly integrated into existing laser rangefinders that use multi-channel recognition circuits as an enhancement function. Without changing the operation of the original long-range detection channel (high magnification circuit), it specifically optimizes the short-range detection performance, resulting in good system compatibility. 4) Improved reliability: It effectively solves the inherent defects of large-aperture long-range laser rangefinders in close-range detection, significantly reduces the probability of ranging errors caused by stray light, and improves the overall combat effectiveness and reliability of the equipment in complex environments. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of an existing laser rangefinder. Figure 2 This is a circuit connection block diagram of an existing laser rangefinder; Figure 3 This is a flowchart of the present invention. Detailed Implementation

[0020] The present invention will now be described in detail so that its advantages and features can be more easily understood by those skilled in the art, thereby providing a clearer and more explicit definition of the scope of protection of the present invention.

[0021] The following provides a brief overview of one or more aspects to offer a basic understanding of them. This overview is not an exhaustive summary of all conceived aspects, nor is it intended to identify key or decisive elements of all aspects, nor to define the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form to prepare for the more detailed descriptions that follow.

[0022] like Figure 3 As shown, this invention discloses a method to improve the short-range detection capability of a laser rangefinder. This method suppresses short-range scattered echo signals, reduces the probability of false signals at close range, and improves short-range ranging accuracy without compromising long-range ranging capability. The method first determines whether measures to suppress stray light are needed by judging the strength of the returned light signal and the effective distance value. If so, the sensitivity of the photoelectric conversion component is reduced to suppress stray light influence and improve ranging accuracy. If the returned signal is weak, the sensitivity of the photoelectric conversion component is increased.

[0023] This invention discloses a method for improving the short-range detection capability of a laser rangefinder, comprising the following steps: (1) The laser rangefinder emits a measuring laser towards the target, receives the returned light signal, and obtains the first signal energy from a low amplification circuit such as the signal recognition circuit 2. It is characterized by the pulse width of the electrical signal generated after the return optical signal is converted by photoelectric conversion. The larger the pulse width, the greater the signal energy value represented. (2) Judgment ,in The minimum energy value at which a scattered echo signal can be misidentified as a valid returned optical signal: If > If the signal is strong, it indicates that the target is at close range and may contain strong scattered echoes, which may generate false signals. Measures need to be taken to suppress stray light at close range and step (3) should be executed. Otherwise, the current working state should be maintained. (3) To reduce the sensitivity of photodetectors such as APDs, the sensitivity can be reduced or increased by adjusting the operating bias voltage of the photodetector. For APDs, the reverse bias voltage can be changed from high voltage to low voltage. Reduced to low pressure To reduce sensitivity, thus enabling < Conversely, reverse bias from low voltage. Restore to high voltage Then the sensitivity will increase; (4) When the photoelectric detection component is in a low-sensitivity state, measure the distance to a nearby target and record the energy of the second signal at this time. ; (5) Judgment :like This indicates that the sensitivity of the photodetector is too low to detect the signal. The sensitivity of the photodetector needs to be increased by changing the reverse bias voltage of the APD from low to high. Restore to high voltage ;like This indicates that even with the current low sensitivity, the effective target signal can still be reliably detected, while stray light has been suppressed. Therefore, the reverse bias voltage of the photodetector component should continue to be maintained. This puts it in a low-sensitivity state; (6) Repeat the above steps.

[0024] This invention also discloses a system for improving the short-range detection capability of a laser rangefinder, employing a method described above for improving the short-range detection capability of a laser rangefinder, including: The laser emitting module is used to emit detection lasers; A photoelectric detection component, used to receive returned optical signals and convert them into electrical signals; The signal processing module includes at least a low amplification circuit for processing electrical signals to obtain signal energy values. The sensitivity control module, connected to the photoelectric detection component, is used to adjust the sensitivity of the photoelectric detection component according to the output of the signal processing module. The sensitivity control module is configured as follows: when Furthermore, when the target distance is close, the photoelectric detection component is controlled to reduce its sensitivity; After performing ranging under low sensitivity conditions, if Then, the photoelectric detection component is controlled to improve its sensitivity.

[0025] The photoelectric detection module includes an APD (Active Photodetector). The sensitivity control module changes the sensitivity by adjusting the reverse bias voltage applied to the APD. This is achieved by changing the reverse bias voltage of the APD from high voltage to low voltage. Reduced to low pressure To reduce sensitivity, the reverse bias voltage of the APD is changed from a low voltage. Restore to high voltage To improve sensitivity.

[0026] Any parts or structures not specifically described in this invention can be made using existing technologies or products, and will not be elaborated upon here.

[0027] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for improving the short-range detection capability of a laser rangefinder, characterized in that, Includes the following steps: (1) The laser rangefinder emits a measuring laser towards the target, receives the returned light signal, and obtains the first signal energy. ; (2) Judgment ,in The minimum energy value at which the scattered echo signal can be mistakenly identified as a valid returned optical signal: if yes, then proceed to step (3); otherwise, maintain the current working state. (3) Reduce the sensitivity of the photoelectric detection component, so that < ; (4) When the photoelectric detection component is in a low-sensitivity state, the target is ranged and the energy of the second signal is recorded. ; (5) Judgment If yes, then increase the sensitivity of the photoelectric detection component; if no, then maintain the photoelectric detection component in a low-sensitivity state. (6) Repeat the above steps.

2. The method for improving the short-range detection capability of a laser rangefinder according to claim 1, characterized in that, In step (1), the first signal energy The pulse width of the electrical signal generated after the return optical signal is converted by photoelectric conversion is used to characterize the signal. The larger the pulse width, the greater the signal energy value.

3. The method for improving the short-range detection capability of a laser rangefinder according to claim 1, characterized in that, In step (1), the first signal energy It is obtained through a low amplification circuit.

4. The method for improving the short-range detection capability of a laser rangefinder according to claim 1, characterized in that, The sensitivity of the photodetector can be reduced or increased by adjusting the operating bias voltage of the photodetector.

5. A method for improving the short-range detection capability of a laser rangefinder according to claim 4, characterized in that, In step (3), the photoelectric detection component is an APD, and the reverse bias voltage of the APD is changed from high voltage. Reduced to low pressure To reduce sensitivity.

6. A method for improving the short-range detection capability of a laser rangefinder according to claim 4, characterized in that, In step (5), the reverse bias of the APD is changed from low voltage. Restore to high voltage To improve sensitivity.

7. A system for improving the short-range detection capability of a laser rangefinder, characterized in that, The method for improving the short-range detection capability of a laser rangefinder, as described in any one of claims 1-6, includes: The laser emitting module is used to emit detection lasers; A photoelectric detection component, used to receive returned optical signals and convert them into electrical signals; The signal processing module includes at least a low amplification circuit for processing electrical signals to obtain signal energy values. A sensitivity control module, connected to the photoelectric detection component, is used to adjust the sensitivity of the photoelectric detection component according to the output of the signal processing module; The sensitivity control module is configured as follows: when Furthermore, when the target distance is close, the photoelectric detection component is controlled to reduce its sensitivity; After performing ranging under low sensitivity conditions, if Then, the sensitivity of the photoelectric detection component is increased.

8. The system for improving the short-range detection capability of a laser rangefinder according to claim 7, characterized in that, The photoelectric detection module includes an APD, and the sensitivity control module changes the sensitivity by adjusting the reverse bias voltage applied to the APD.

9. A system for improving the short-range detection capability of a laser rangefinder according to claim 8, characterized in that, By changing the reverse bias of the APD from high voltage Reduced to low pressure To reduce sensitivity.

10. A system for improving the short-range detection capability of a laser rangefinder according to claim 8, characterized in that, By changing the reverse bias of the APD from low voltage Restore to high voltage To improve sensitivity.

Images