Laser range finder and range finding system
By using a light source in the medium and long-wave infrared band to emit infrared pulses in the laser rangefinder, and combining it with high-sensitivity detectors and signal processing technology, the problem that existing laser rangefinders are easily detected is solved, and covert ranging and Reduce the false alarm rate.
Patent Information
- Application Number
- CN202310843969.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-07-11
- Publication Date
- 2025-01-14
AI Technical Summary
Existing laser rangefinders are easily detected by distancefinder targets when working, resulting in alarm triggering and lack of concealment.
A light source with an emission wavelength in the mid- to long-wave infrared band is used to emit infrared pulses to the object being measured. The infrared pulses in this band can be well hidden in the background light and are not easily detected by the object being measured. It is coupled with high-sensitivity detectors and signal processing. technology to achieve covert ranging.
Through infrared pulses hidden in the background light, the laser rangefinder can complete covert ranging, avoid being detected by ranging targets, and reduce the false alarm rate.
Smart Images
Figure CN119310578A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of distance measurement, and in particular to a laser distance meter and a distance measurement system. Background Art
[0002] Laser rangefinders are widely used due to their high precision and ease of use. Currently, laser rangefinders can be basically divided into two categories: indoor ranging and outdoor ranging. Indoor ranging usually does not exceed 200m at most and is not affected by the background light of the sun. For the sake of eye safety, red and green lasers visible to the human eye are often used. Outdoor ranging is basically more than 500m, and 905nm near-infrared lasers are often used, which are greatly affected by the background light of the sun. However, these laser rangefinders currently do not consider the issue of concealment, and are easily detected directly or indirectly by the ranging target when working, thereby triggering an alarm.
[0003] Therefore, how to provide a solution to the above technical problems is a problem that those skilled in the art need to solve at present. Summary of the invention
[0004] The purpose of the present application is to provide a laser rangefinder and a ranging system, which use a light source with an emission wavelength in the medium and long-wave infrared band to emit infrared pulses to the object to be measured. The infrared pulses in this band can be well hidden in the background light and are not easily detected by the object to be measured, thereby completing covert ranging.
[0005] In order to solve the above technical problems, the present application provides a laser rangefinder, comprising:
[0006] The light source whose current emission wavelength is in the mid- and long-wave infrared band is used to emit infrared pulses to the object under test;
[0007] A detection component, used for detecting an echo signal returned based on the infrared pulse;
[0008] A processing component is used to process the echo signal to obtain a valid echo signal, and obtain the distance information of the measured object based on the valid echo signal.
[0009] Optionally, the light source is used to send infrared pulses with a repetition frequency greater than a first preset value to the object under test;
[0010] The processing component is used to superimpose the received echo signals, extract effective echo signals using the superimposed echo signals, and obtain the distance information of the measured object based on the effective echo signals.
[0011] Optionally, the light source is used to send infrared pulses with a repetition frequency greater than a first preset value and a power less than a second preset value to the object under test.
[0012] Optionally, the light source is further used to determine environmental information of a current location, and adjust the wavelength based on the environmental information.
[0013] Optionally, the process of determining environmental information of the current location and adjusting the wavelength based on the environmental information includes:
[0014] When it is determined that the environmental information of the current location is the first environmental information, the current emission wavelength is adjusted to the first wavelength; the first environmental information includes that the number of suspended particles is greater than a third preset value and / or the visibility is lower than a fourth preset value;
[0015] and / or,
[0016] When it is determined that the environmental information of the current location is the second environmental information, the current emission wavelength is adjusted to the second wavelength; the second wavelength is smaller than the first wavelength; the second environmental information includes that the intensity of the long-wave absorption ability is greater than the preset intensity.
[0017] Optionally, the detection component includes:
[0018] A receiving unit, used for receiving an echo signal returned based on the infrared pulse;
[0019] A filtering unit is used to filter the echo signal.
[0020] Optionally, the filtering unit includes filters corresponding to each preset wavelength.
[0021] Optionally, the processing component is further used to determine a current emission wavelength of the light source, and switch the filter of the filtering unit based on the current emission wavelength, so as to filter the echo signal through the filter corresponding to the current emission wavelength.
[0022] Optionally, the light source comprises a quantum cascade laser.
[0023] Optionally, the detection assembly includes a cooled large-photosensitive-surface Type II SLS superlattice detector or an MCT mercury cadmium telluride detector.
[0024] To solve the above technical problems, the present application also provides a distance measurement system, including a laser rangefinder as described in any one of the above.
[0025] The present application provides a laser rangefinder, wherein the transmitting end of the laser rangefinder uses a light source with a wavelength in the medium and long-wave infrared band to transmit infrared pulses to the measured object, and the receiving end extracts effective information from the echo signal returned based on the infrared pulse, and obtains the distance information of the measured object based on the effective echo signal. The infrared pulse in this band can be well hidden in the background light and is not easily detected by the measured object, so that concealed distance measurement can be completed. The present application also provides a distance measurement system, which has the same beneficial effects as the above-mentioned laser rangefinder. BRIEF DESCRIPTION OF THE DRAWINGS
[0026] In order to more clearly illustrate the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.
[0027] Figure 1 A schematic diagram of the structure of a laser rangefinder provided in this application;
[0028] Figure 2 A schematic diagram of a solar radiation spectrum provided in this application;
[0029] Figure 3 A schematic diagram of a blackbody radiation spectrum at 300K provided in this application;
[0030] Figure 4 This is a schematic diagram of the structure of another laser rangefinder provided in this application. DETAILED DESCRIPTION
[0031] The core of this application is to provide a laser rangefinder and ranging system, which uses a light source with an emission wavelength in the medium and long-wave infrared band to emit infrared pulses to the object to be measured. The infrared pulses in this band can be well hidden in the background light and are not easily detected by the object to be measured, thereby completing covert ranging.
[0032] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.
[0033] First, please refer to Figure 1 , Figure 1 This is a schematic diagram of the structure of a laser rangefinder provided in this application, the laser rangefinder comprises:
[0034] A light source 1 whose current emission wavelength is in the mid- and long-wave infrared band is used to emit infrared pulses to the object under test;
[0035] A detection component 2, used for detecting an echo signal based on the return of the infrared pulse;
[0036] The processing component 3 is used to process the echo signal to obtain a valid echo signal, and obtain the distance information of the measured object based on the valid echo signal.
[0037] To facilitate understanding of the solution of this application, the background radiation in daily environment is first explained. There are two main types of radiation in daily environment, namely solar radiation and black body radiation. Solar radiation is mainly concentrated in the short-wave near-infrared band of 300nm-2500nm, such as Figure 2 As shown, and it almost does not exist at night, so the laser rangefinder using this band light source 1 is easy to be found when used at night, and the blackbody radiation is mainly concentrated in the medium and long wave infrared bands, and changes with temperature, that is, when the temperature rises, it moves to the short wave as a whole, and when the temperature drops, it moves to the long wave as a whole, as shown in Figure 3 As shown. Considering that objects in the natural environment have radiation characteristics similar to those of a black body, especially non-metallic objects, their radiation ratio relative to a black body, that is, the emissivity, is usually above 0.9 or even 0.95, such as the emissivity of human skin at 32°C is 0.98; and the emissivity of a polished metal plate is usually within 0.1, but the emissivity after surface treatment such as oxidation or severe rust is usually above 0.5. Blackbody radiation is only related to the material of the object and its temperature. As mentioned above, most objects in nature have an emissivity close to that of a black body and have always existed. Based on this, this embodiment uses a light source 1 in the medium and long-wave infrared band as the transmitting end of the laser rangefinder. The infrared pulse beam emitted during ranging can be well hidden in the background light, thereby avoiding detection by the laser warning device of the measured object.
[0038] It can be understood that after the light source 1 sends an infrared pulse to the object to be measured through the collimating lens, an echo signal will be returned through the object to be measured. The detection component 2 detects the echo signal and sends the detected echo signal to the processing component 3. The processing component 3 processes the received echo signal. The processing includes extracting the effective echo signal from the echo signal, and then identifying the distance between itself and the object to be measured based on the effective echo signal.
[0039] It can be seen that in this embodiment, the transmitting end of the laser rangefinder uses a light source with an emission wavelength in the medium and long wave infrared band to transmit infrared pulses to the object to be measured, and the receiving end extracts effective information from the echo signal returned based on the infrared pulse, and obtains the distance information of the object to be measured based on the effective echo signal. The infrared pulses in this band can be well hidden in the background light and are not easily detected by the object to be measured, so that covert ranging can be completed.
[0040] Please refer to Figure 4 , Figure 4 This is a schematic diagram of the structure of another laser rangefinder provided in this application. The laser rangefinder is based on the above embodiment:
[0041] In some embodiments, the light source 1 is used to send infrared pulses with a repetition frequency greater than a first preset value to the object under test;
[0042] The processing component 3 is used to superimpose the received echo signals, extract the effective echo signals using the superimposed echo signals, and obtain the distance information of the measured object based on the effective echo signals.
[0043] In some embodiments, the light source 1 is used to send infrared pulses with a repetition frequency greater than a first preset value and a power less than a second preset value to the object under test.
[0044] In order to further reduce the probability of the laser rangefinder being detected by the object to be measured, the light source 1 in this embodiment can emit low-power, high-repetition-rate infrared pulses to the object to be measured. Since the average power of the infrared pulses emitted by the light source 1 is extremely low, even if they are detected by the alarm device of the object to be measured, they cannot be distinguished from the background noise. Among them, the second preset value is the power value at which the infrared pulse cannot be distinguished from the background noise. It can be understood that each infrared pulse will correspond to an echo signal. Since the infrared pulse power is low, the echo signal is also relatively weak. The first preset value is the number of infrared pulses emitted that can satisfy the extraction of valid echo signals from multiple echo signals.
[0045] It can be understood that since the transmitting end uses ultra-low transmitting power infrared pulses, both the transmitting end and the measured end have strong background noise radiation. In addition, due to the influence of long-distance ranging, the transmitting and echo signals will be completely submerged in the background noise. Processing component 3 needs to perform further signal processing on the received echo signal. Since the transmitting end uses high-repetition-rate infrared pulses, such as 100kHz, a signal accumulation scheme can be used to superimpose several echoes to strengthen the effective signal. When the measured object is fixed and does not move, its reflected echo signal is also fixed. Ideally, the power of N echo signals superimposed is N. 2 times, and there is no correlation between background noises. The noise power after N times of superposition is N times, so the signal-to-noise ratio SNR will be increased N times after N times of superposition. Based on this, the processing component 3 can superimpose all the received echo signals to effectively extract extremely weak echo signals from the strong background noise.
[0046] In some embodiments, the light source 1 is also used to determine environmental information of the current location and adjust the wavelength based on the environmental information.
[0047] In some embodiments, determining environmental information of a current location and adjusting the wavelength based on the environmental information includes:
[0048] When it is determined that the environmental information of the current location is the first environmental information, the current emission wavelength is adjusted to the first wavelength; the first environmental information includes that the number of suspended particles is greater than a third preset value and / or the visibility is lower than a fourth preset value;
[0049] and / or,
[0050] When it is determined that the environmental information of the current location is the second environmental information, the current emission wavelength is adjusted to the second wavelength; the second wavelength is smaller than the first wavelength; the second environmental information includes that the intensity of the long-wave absorption capacity is greater than the preset intensity.
[0051] The wavelength of the light source 1 in this embodiment is adjustable so as to adapt to various environments in which the laser rangefinder is used, thereby improving the universality of the laser rangefinder. The laser rangefinder first determines the environmental information of its current location, and adjusts the wavelength based on the environmental information. Different environmental information corresponds to different wavelengths. The correspondence between different environmental information and wavelengths can be preset so that the current emission wavelength of the light source 1 can be determined directly based on the currently acquired environmental information and the correspondence. When the environmental information changes, the wavelength can be quickly adjusted to adapt to the current use environment and improve efficiency. Environmental information includes but is not limited to the number of suspended particles in the atmosphere, visibility, and the intensity of long-wave absorption capacity. Specifically, when there are many suspended particles in the atmosphere and visibility is low, a longer wavelength can be used, while when the long-wave absorption is relatively large in rainy and foggy weather, a shorter wavelength can be used. Among them, the values of the third preset value, the fourth preset value, and the preset intensity are all set according to actual engineering needs, and this embodiment does not make specific limitations here.
[0052] It can be understood that the adjustment of the wavelength of the light source 1 can be achieved actively or passively. Actively, the light source 1 detects the environmental information of the current location and adjusts its current emission wavelength according to the environmental information. Passively, the processing component 3 in the laser rangefinder obtains the environmental information and then outputs an adjustment instruction based on the environmental information. The light source 1 adjusts its current emission wavelength according to the received adjustment instruction.
[0053] Among them, the lasers with emission wavelengths in the mid- and long-wave infrared band include 10.6um CO2 lasers and QCL (Quantum Cascade Laser), etc. Any of the above lasers can be selected as the light source 1 in this embodiment.
[0054] QCL lasers are different from traditional semiconductor lasers in that they generate lasers by the recombination of conduction band electrons and valence band holes. Instead, they generate lasers in the mid-to-far infrared and even terahertz bands by electrons in semiconductor materials transitioning between sub-bands of the conduction band and phonon resonance-assisted tunneling amplification. Moreover, since its wavelength is determined by the energy difference between the sub-bands, the wavelength can be changed by changing the thickness of the quantum well layer, thereby providing the possibility of changing the wavelength in real time. The power of QCL lasers is relatively low, usually with an average power of mW level and a peak power of W level, but its repetition rate is very high, so it can be used as the light source 1 in this embodiment. It can be understood that the long-wave band of 8-14um has a relatively high transmittance in the atmosphere, and has a relatively strong penetration of suspended particles in the air such as sand and dust, and has good performance in such low visibility conditions, so it can improve the ranging accuracy. Under adverse meteorological conditions such as rain and fog, it can be selected to adjust the wavelength to a medium-wave band of about 5um to reduce the absorption of the outgoing light by rain and fog, so that better ranging results can be achieved even in bad weather.
[0055] In some embodiments, the detection assembly 2 includes:
[0056] A receiving unit, used for receiving an echo signal returned based on the infrared pulse;
[0057] The filtering unit 21 is used to filter the echo signal.
[0058] In this embodiment, the detection component 2 includes a receiving unit and a filtering unit 21. The receiving unit includes a receiving lens 221 and a detector 222. Considering that a cooling function is usually required to achieve better performance, a large-area single-pixel device can be selected to receive the echo signal, such as a photosensitive surface with a diameter of 2mm. Its equivalent noise power under cooling conditions can be as low as 1E-15W.Hz-0.5, which basically reaches the detection level of the photon level. The filtering unit 21 is used to filter out background stray light in other bands to reduce the impact of noise.
[0059] The detector 222 includes but is not limited to a type II superlattice SLS detector and a mercury cadmium telluride MCT detector.
[0060] In some embodiments, the filtering unit 21 includes filters corresponding to various preset wavelengths.
[0061] The filtering unit 21 may include multiple narrowband filters, each narrowband filter corresponds to a preset wavelength, and the preset wavelength can be determined according to the emitting wavelength of the light source 1. In this embodiment, the filter can be replaced according to the current emission wavelength of the light source 1. Specifically, the filter is detachably arranged on the surface of the laser rangefinder so that the user can install the corresponding narrowband filter according to the current actual use environment, so as to filter corresponding to different emission wavelengths through the currently installed narrowband filter.
[0062] In other embodiments, the processing component 3 is further used to determine the current emission wavelength of the light source 1, and switch the filter of the filtering unit 21 based on the current emission wavelength, so as to filter the echo signal through the filter corresponding to the current emission wavelength.
[0063] A plurality of narrowband filters corresponding to different preset wavelengths can be pre-configured in the laser rangefinder, and the processing component 3 switches each narrowband filter based on the current emission wavelength of the light source 1, thereby improving the switching efficiency and better adapting to the changes in the use environment of the laser rangefinder and improving the ranging accuracy.
[0064] It can be understood that the variable wavelength can reduce or eliminate the possibility of the laser warning device of the measured object using a filter to improve the warning performance, further reducing the possibility of being perceived during ranging.
[0065] In summary, the laser rangefinder in the present application uses the long-wave infrared band (8-14um) and the medium-wave infrared of about 5um widely existing in the natural environment and radiated by various natural objects as the light source 1, and emits a high-repetition-rate, low-power pulse light beam that is completely submerged in the broad-spectrum background light existing in all time periods for ranging. The receiving end uses a highly sensitive detector such as a mercury cadmium telluride detector to receive the echo signal. Due to the high-repetition-rate transmission, a large number of echo signals can be accumulated to strengthen the actual signal. At the same time, a denoising algorithm is used to further improve the signal-to-noise ratio (SNR) of the system, so as to smoothly extract the echo signal and obtain the required distance information at a low false alarm rate, while being unnoticed or difficult to be detected by the target, thereby achieving covert ranging.
[0066] In a second aspect, the present application also provides a ranging system, comprising a laser rangefinder as described in any one of the above embodiments.
[0067] For an introduction to a distance measurement system provided in this embodiment, please refer to the above embodiment, and this application will not go into details here.
[0068] The distance measuring system provided in the present application has the same beneficial effects as the above-mentioned laser distance measuring device.
[0069] It should also be noted that, in this specification, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprises", "comprising" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the statement "comprising a ..." does not exclude the presence of other identical elements in the process, method, article or device including the element.
[0070] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.
Claims
1. A laser rangefinder, characterized in that: include: The light source whose current emission wavelength is in the mid- and long-wave infrared band is used to emit infrared pulses to the object under test; A detection component, used for detecting an echo signal returned based on the infrared pulse; A processing component is used to process the echo signal to obtain a valid echo signal, and obtain the distance information of the measured object based on the valid echo signal.
2. The laser rangefinder according to claim 1, characterized in that: The light source is used to send infrared pulses with a repetition frequency greater than a first preset value to the object under test; The processing component is used to superimpose the received echo signals, extract effective echo signals using the superimposed echo signals, and obtain the distance information of the measured object based on the effective echo signals.
3. The laser rangefinder according to claim 2, characterized in that: The light source is used to send infrared pulses with a repetition frequency greater than a first preset value and a power less than a second preset value to the object under test.
4. The laser rangefinder according to claim 1, characterized in that: The light source is also used to determine environmental information of a current location and adjust the wavelength based on the environmental information.
5. The laser rangefinder according to claim 4, characterized in that: The process of determining the environmental information of the current location and adjusting the wavelength based on the environmental information includes: When it is determined that the environmental information of the current location is the first environmental information, the current emission wavelength is adjusted to the first wavelength; the first environmental information includes that the number of suspended particles is greater than a third preset value and / or the visibility is lower than a fourth preset value; and / or, When it is determined that the environmental information of the current location is the second environmental information, the current emission wavelength is adjusted to the second wavelength; the second wavelength is smaller than the first wavelength; the second environmental information includes that the intensity of the long-wave absorption ability is greater than the preset intensity.
6. The laser rangefinder according to claim 1, characterized in that: The detection component comprises: A receiving unit, used for receiving an echo signal returned based on the infrared pulse; A filtering unit is used to filter the echo signal.
7. The laser rangefinder according to claim 6, characterized in that: The filtering unit includes filters corresponding to various preset wavelengths.
8. The laser rangefinder according to claim 7, characterized in that: The processing component is also used to determine a current emission wavelength of the light source, and switch the filter of the filtering unit based on the current emission wavelength, so as to filter the echo signal through the filter corresponding to the current emission wavelength.
9. The laser rangefinder according to any one of claims 1 to 8, characterized in that: The light source comprises a quantum cascade laser.
10. The laser rangefinder according to any one of claims 1 to 8, characterized in that: The detection component includes a cooling type large photosensitive surface type II SLS superlattice detector or an MCT mercury cadmium telluride detector.
11. A distance measurement system, characterized in that: Comprising a laser rangefinder as described in any one of claims 1-10.