A long-distance high-precision laser range finder

Abstract

The present application relates to laser ranging technical field, especially a kind of long-distance high-precision laser range finder.Receiving optical assembly is the structure of multiple lens cooperation correction, including sequentially arranged condenser lens, aberration suppression lens, focusing lens and gain compensation lens along the transmission direction of laser reflection signal;Condenser lens is responsible for efficient convergence weak laser reflection signal after long-distance transmission, aberration suppression lens is aimed at inhibiting spherical aberration, chromatic aberration, focusing lens ensures that laser reflection signal accurately falls on the photosensitive surface of photoelectric conversion piece, and gain compensation lens stabilizes the intensity of laser reflection signal.To achieve excellent optical performance, four sets of lenses are matched in parameters to effectively balance the overall optical performance of the whole receiving optical assembly.And in the axial spacing of adjacent two lenses, it needs to follow the cooperative calculation rule based on focal length.In this way, not only the light energy loss of laser reflection signal in the transmission process can be effectively avoided, but also the distortion problem of image plane can be prevented.

Description

Technical Field

[0001] This invention relates to the field of laser ranging technology, and in particular to a long-distance, high-precision laser rangefinder. Background Technology

[0002] Long-range, high-precision laser ranging technology is widely used in surveying and exploration, power line inspection, and construction engineering. Its core requirement is to control the measurement error within ±5mm within a ranging range of 100m to 5000m to meet the precise positioning requirements of the target. During the operation of the rangefinder, the laser beam output by the laser emitting unit is reflected by the target, captured by the laser receiving unit, and converted into an electrical signal. The signal control module then calculates the time delay to obtain the distance data. The laser receiving unit's ability to accurately capture the reflected signal directly determines the upper limit of the ranging accuracy.

[0003] Existing long-range laser rangefinders typically employ simplified configurations for their laser receiving units, focusing the optical and photoelectric conversion sections: a single condenser lens converges the reflected signal, a stray light filter reduces ambient light interference, and a photoelectric conversion element converts the optical signal into an electrical signal. While some designs increase this to a combination of two optical lenses (a condenser lens and a focusing lens), the overall structure remains basic. However, in long-range ranging scenarios, reflected laser signals are characterized by weak intensity, long propagation paths, and susceptibility to ambient stray light interference. The design flaws of existing receiving optical structures are primarily in insufficient aberration correction capabilities: firstly, single-lens or double-lens structures struggle to simultaneously suppress spherical and chromatic aberrations, especially when there is a slight shift in the incident angle of the reflected laser signal. Lens aberrations can cause the light spot to shift or diffuse on the photosensitive surface of the photoelectric conversion element, preventing the element from accurately capturing the signal peak and introducing time delay measurement errors. Secondly, existing technologies do not coordinate the design of lens optical parameters and lens spacing, relying solely on empirical values ​​to determine lens selection and assembly distances, resulting in a lack of complementary optical characteristics between different lenses. For example, while a high refractive index of a condenser lens can improve light-gathering efficiency, it can also exacerbate chromatic aberration. If the focusing lens is not matched with the corresponding Abbe constant, it cannot compensate for this chromatic aberration, which ultimately leads to a decrease in the signal-to-noise ratio of the received signal and further affects the ranging accuracy.

[0004] Taking surveying and exploration scenarios as an example, when using an existing rangefinder to measure a target 2000m away, due to the aberration of the receiving optical system, the dispersion diameter of the light spot on the photoelectric conversion element can reach more than 0.1mm, which will inevitably lead to a time delay measurement deviation of more than 10ps, corresponding to a ranging error of more than 1.5mm. If ambient light interference is superimposed, the final ranging error will be seriously out of tolerance, which cannot meet the requirements of high-precision applications.

[0005] Therefore, it is imperative for those skilled in the art to solve the aforementioned problems. Summary of the Invention

[0006] The purpose of this invention is to provide a long-distance, high-precision laser rangefinder, which aims to solve the problems of insufficient aberration correction capability of the receiving optical structure in existing designs, difficulty in suppressing spherical aberration and chromatic aberration leading to spot dispersion by single / dual lenses, and lack of coordinated design of lens parameters and spacing, and inability to complement each other's optical characteristics, ultimately causing excessive ranging errors.

[0007] This invention relates to a long-range, high-precision laser rangefinder, comprising a signal control module, a laser emitting unit, and a laser receiving unit. The signal control module is electrically connected to both the laser emitting unit and the laser receiving unit to achieve coordinated operation of emission control, signal reception, and distance calculation. The laser receiving unit includes a receiving lens tube and receiving optical components, stray light filters, and photoelectric conversion components arranged sequentially along the laser reflection signal transmission direction. The optical axes of the receiving optical components, stray light filters, and photoelectric conversion components are collinear, and all three are assembled inside the receiving lens tube. The receiving optical assembly is a multi-lens cooperative correction structure, including a condenser lens, an aberration suppression lens, a focusing lens, and a gain compensation lens arranged sequentially along the laser reflection signal transmission direction; the refractive indices of the condenser lens, aberration suppression lens, focusing lens, and gain compensation lens satisfy a complementary fit relationship with the Abbe constant. (Nd1×Vd1+Nd2×Vd2+Nd3×Vd3+Nd4×Vd4) / 4≤T; In the formula, Nd1 is the refractive index of the condenser lens, and Vd1 is the Abbe constant of the condenser lens; Nd2 is the refractive index of the aberration suppression lens, and Vd2 is the Abbe constant of the aberration suppression lens; Nd3 is the refractive index of the focusing lens, and Vd3 is the Abbe constant of the focusing lens; Nd4 is the refractive index of the gain compensation lens, and Vd4 is the Abbe constant of the gain compensation lens; T is the adaptation threshold, and 85≤T≤95; The axial distances between the condenser lens and the aberration-suppressing lens, the axial distances between the aberration-suppressing lens and the focusing lens, and the axial distances between the focusing lens and the gain-compensating lens all satisfy the focal length coordination formula: d_adj=β×[α×f_prev+(1-α)×f_next]; In the formula, d_adj represents the axial distance between the condenser lens and the aberration suppression lens, the axial distance between the aberration suppression lens and the focusing lens, and the axial distance between the focusing lens and the gain compensation lens, respectively; α is the focal length weighting coefficient, and 0.4≤α≤0.6; when calculating the distance between the condenser lens and the aberration suppression lens, f_prev is the focal length of the condenser lens, and f_next is the focal length of the aberration suppression lens; when calculating the distance between the aberration suppression lens and the focusing lens, f_prev is the focal length of the aberration suppression lens, and f_next is the focal length of the focusing lens; when calculating the distance between the focusing lens and the gain compensation lens, f_prev is the focal length of the focusing lens, and f_next is the focal length of the gain compensation lens; β is the coordination coefficient, and 0.05≤β≤0.12.

[0008] As a further improvement to the technical solution disclosed in this invention, the stray light filter is a multi-layer coated interference filter, and its reference transmittance is... satisfy Furthermore, only laser reflection signals with wavelengths ranging from 0.9μm to λ to 1.6μm are allowed to pass through.

[0009] As a further improvement to the technical solution disclosed in this invention, the number of coating layers n of the multilayer coated interference filter satisfies 5 layers ≤ n ≤ 15 layers, the average thickness d_avg of the coating layer satisfies 50nm ≤ d_avg ≤ 200nm, and the thickness deviation of each coating layer does not exceed 5% of the average thickness.

[0010] As a further improvement to the technical solution disclosed in this invention, the reverse bias voltage V_bias of the photoelectric conversion device satisfies 50V≤V_bias≤200V, the dark current I_dark does not exceed 10nA, and the dark current decreases as the reverse bias voltage increases.

[0011] As a further improvement to the technical solution disclosed in this invention, the photoelectric conversion device adopts an avalanche photodiode, whose reference avalanche gain M0 satisfies 100≤M0≤500, and the avalanche gain is dynamically adjusted according to the incident laser reflected signal light power, with the incident light power range being 0.1μW≤P_in≤0.5μW.

[0012] As a further improvement to the technical solution disclosed in this invention, the laser emitting unit includes a laser diode and an emitting optical lens group; the reference output optical power P_ref of the laser diode satisfies 5mW≤P_ref≤20mW, and the operating temperature range is -10℃≤T≤60℃.

[0013] As a further improvement to the technical solution disclosed in this invention, the inner wall of the receiving lens tube is provided with a light-absorbing coating, and the reflectivity of the light-absorbing coating is... The thickness h satisfies 10μm≤h≤50μm.

[0014] As a further improvement to the technical solution disclosed in this invention, the signal control module includes a microprocessor and a signal conditioning circuit; the distance calculation formula used by the microprocessor when performing distance calculation is as follows: L=(c×t_delay) / 2; Where L is the measurement distance in meters; c is the speed of light in a vacuum; t_delay is the time delay from laser signal transmission to reception in seconds; the signal conditioning circuit amplifies the electrical signal output by the photoelectric converter, with the amplification factor A satisfying 100≤A≤1000, the input electrical signal amplitude range being 0.001V≤V_in≤0.01V, and the target output signal amplitude range being 0.5V≤K≤2V.

[0015] As a further improvement to the technical solution disclosed in this invention, the emitting optical lens group includes a collimating lens and a beam expander arranged sequentially along the laser output direction; the focal length f_col of the collimating lens satisfies 5mm≤f_col≤20mm, the focal length f_beam of the beam expander satisfies 20mm≤f_beam≤50mm, and the axial distance d_beam between the collimating lens and the beam expander is the sum of the focal lengths of the two lenses, with a deviation of ±2mm allowed; the beam divergence angle θ of the emitting optical lens group satisfies 0.1mrad≤θ≤1mrad.

[0016] In practical applications, the long-distance high-precision laser rangefinder disclosed in this invention can achieve at least the following beneficial technical effects, specifically: 1) In the receiving optical assembly, a condenser lens, an aberration suppression lens, a focusing lens, and a gain compensation lens are arranged sequentially along the direction of laser reflection signal transmission: the condenser lens can efficiently gather the weak reflected signal after long-distance transmission; the aberration suppression lens can specifically suppress optical distortions such as spherical aberration and chromatic aberration; the focusing lens ensures that the signal accurately falls on the photosensitive surface of the photoelectric conversion element; and the gain compensation lens further stabilizes the signal strength. This multi-lens collaborative working mode provides assurance from all key aspects of signal reception, laying a good foundation for high-quality signal capture in long-distance scenarios; 2) For condenser lenses, aberration suppression lenses, focusing lenses, and gain compensation lenses, specific adaptation relationships constrain the optical parameters of each lens. This adaptation relationship explicitly requires that the average value of the sum of the products of the refractive index and Abbe constant of the condenser lens, the aberration suppression lens, the focusing lens, and the gain compensation lens does not exceed an adaptation threshold T. This achieves complementarity in the dispersion characteristics of different lenses, effectively balancing overall optical performance. Furthermore, a quantitative formula is used to determine the axial spacing between the condenser lens and the aberration suppression lens, the aberration suppression lens and the focusing lens, and the focusing lens and the gain compensation lens. This quantitative formula is based on the focal length of each adjacent lens group, combined with reasonable values ​​for the focal length weighting coefficient and the coordination coefficient, ensuring that the spacing of each pair of adjacent lenses is precisely adapted to the focal length characteristics of the two lens groups. By quantitatively constraining the optical parameters of the lens and accurately calculating the axial spacing between adjacent lenses, we can avoid the loss of light energy in the laser reflection signal and prevent image distortion, ultimately achieving a deep match between the structure and the parameters. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a three-dimensional schematic diagram of the long-distance high-precision laser rangefinder disclosed in this invention.

[0019] Figure 2 This is a schematic diagram of the laser receiving module in the long-distance high-precision laser rangefinder disclosed in this invention.

[0020] Figure 3 This is a schematic diagram of the laser emission optical path module in the long-distance high-precision laser rangefinder disclosed in this invention.

[0021] 1-Signal control module; 2-Laser emitting unit; 21-Laser emitter; 22-Emitting optical lens group; 221-Emitting lens barrel; 222-Colliding lens; 223-Beam expander lens; 3-Laser receiving unit; 31-Receiving lens barrel; 32-Receiving optical assembly; 321-Condensing lens; 322-Aberration suppression lens; 323-Focusing lens; 324-Gain compensation lens; 33-Stray light filter; 34-Photoelectric conversion component. Detailed Implementation

[0022] The present invention will be further described in detail below with reference to specific embodiments. For example... Figure 1 As shown, the long-range high-precision laser rangefinder disclosed in this invention is mainly used for high-precision measurement needs in long-distance scenarios. It mainly consists of a signal control module 1, a laser emitting unit 2, and a laser receiving unit 3. The signal control module 1 is electrically connected to both the laser emitting unit 2 and the laser receiving unit 3, thereby enabling coordinated operation of laser emission control, reflected signal reception, and distance calculation. The laser emitting unit 2 and the laser receiving unit 3 are arranged in parallel and are both electrically connected to the signal control module 1, ensuring the timeliness and stability of signal transmission between the modules.

[0023] As the core component for receiving and processing laser reflection signals, the laser receiving unit 3's internal structure must meet the requirements of stability and accuracy for long-distance transmission of weak signals. Specifically, for example... Figure 1 , Figure 2 As shown, the laser receiving unit 3 includes a receiving lens barrel 31, a receiving optical component 32, a stray light filter 33, and a photoelectric conversion component 34. According to the transmission direction of the laser reflected signal, the receiving optical component 32, the stray light filter 33, and the photoelectric conversion component 34 are sequentially and spaced apart inside the receiving lens barrel 31, and the optical axes of the three are kept collinear to ensure that the laser reflected signal is not deflected during transmission, providing a basis for subsequent precise focusing and signal conversion.

[0024] To achieve efficient focusing, aberration suppression, and signal gain compensation of long-distance laser reflection signals, the receiving optical component 32 adopts a four-lens synergistic correction structure, consisting of a condenser lens 321, an aberration suppression lens 322, a focusing lens 323, and a gain compensation lens 324, arranged sequentially along the transmission direction of the laser reflection signal. The condenser lens 321 primarily performs the initial focusing function of the weak laser reflection signal after long-distance transmission; the aberration suppression lens 322 is responsible for specifically correcting optical distortions such as spherical aberration and chromatic aberration generated during transmission; the focusing lens 323 precisely focuses the corrected signal onto the photosensitive surface of the photoelectric conversion element 34; and the gain compensation lens 324 further stabilizes the signal strength. These four elements complement each other to form a synergistic effect.

[0025] Furthermore, to ensure stable synergistic effects, the refractive indices and Abbe constants of the condenser lens 321, aberration suppression lens 322, focusing lens 323, and gain compensation lens 324 must satisfy a complementary fit relationship. This achieves complementarity in the dispersion characteristics of different lenses, effectively balancing the overall optical performance. The fit relationship formula is as follows: (Nd1×Vd1+Nd2×Vd2+Nd3×Vd3+Nd4×Vd4) / 4≤T; In the above formula, Nd1 is the refractive index of the condenser lens 321, and Vd1 is the Abbe constant of the condenser lens 321; Nd2 is the refractive index of the aberration suppression lens 322, and Vd2 is the Abbe constant of the aberration suppression lens 322; Nd3 is the refractive index of the focusing lens 323, and Vd3 is the Abbe constant of the focusing lens 323; Nd4 is the refractive index of the gain compensation lens 324, and Vd4 is the Abbe constant of the gain compensation lens 324; T is the adaptation threshold, and 85≤T≤95. Through this adaptation constraint, signal transmission distortion caused by mismatch of optical parameters of each lens can be avoided.

[0026] Meanwhile, the axial distances between the condenser lens 321 and the aberration suppression lens 322, the axial distances between the aberration suppression lens 322 and the focusing lens 323, and the axial distances between the focusing lens 323 and the gain compensation lens 324 must all satisfy the focal length coordination formula to precisely control the distances between each lens and ensure the synergistic effect of optical performance. The formula is as follows: d_adj=β×[α×f_prev+(1-α) ×f_next]; In the above formulas, d_adj represents the axial distance between the condenser lens 321 and the aberration suppression lens 322, the axial distance between the aberration suppression lens 322 and the focusing lens 323, and the axial distance between the focusing lens 323 and the gain compensation lens 324, respectively; α is the focal length weighting coefficient, and 0.4≤α≤0.6; when calculating the distance between the condenser lens 321 and the aberration suppression lens 322, f_prev is the focal length of the condenser lens 321, and f_next is the focal length of the aberration suppression lens 322; when calculating the distance between the aberration suppression lens 322 and the focusing lens 323, f_prev is the focal length of the aberration suppression lens 322, and f_next is the focal length of the focusing lens 323; when calculating the distance between the focusing lens 323 and the gain compensation lens 324, f_prev is the focal length of the focusing lens 323, and f_next is the focal length of the gain compensation lens 324; β is the coordination coefficient, and 0.05≤β≤0.12. By combining the calculation of this focal length coordination formula, the focusing function of the condenser lens 321, the aberration correction function of the aberration suppression lens 322, the signal focusing function of the focusing lens 323, and the signal gain compensation function of the gain compensation lens 324 can be deeply linked, effectively reducing light energy loss and image plane distortion, and providing stable optical support for long-distance ranging accuracy.

[0027] As a further optimization of the receiving lens tube 31, its inner wall is provided with a light-absorbing coating, the reflectivity of which is... The thickness h satisfies 10μm≤h≤50μm, which can effectively reduce stray light reflection from the inner wall of the receiving lens tube 31, avoid stray light interference with the received signal of the photoelectric conversion component 34, and further improve signal purity, especially suitable for the accurate capture of weak signals in long-distance scenarios.

[0028] In the laser receiving unit 3, the selection of the stray light filter 33 is also crucial to the signal quality. It is a multi-layer coated interference filter with a reference transmittance of [missing information]. satisfy Only laser reflection signals with wavelengths in the range of 0.9μm ≤ λ ≤ 1.6μm are allowed to pass through, thus precisely filtering stray light in the environment and retaining only the laser reflection signal of the target wavelength, further improving the accuracy of the signal received by the photoelectric conversion device 34. Furthermore, to ensure the stability of the stray light filtering effect, the number of coating layers n of the multilayer coated interference filter meets the requirement of 5 layers ≤ n ≤ 15 layers, the average thickness d_avg of the coating layers meets the requirement of 50nm ≤ d_avg ≤ 200nm, and the thickness deviation of each coating layer does not exceed 5% of the average thickness. By strictly controlling the coating parameters, stray light filtering failure caused by unstable coating layer characteristics is avoided.

[0029] The photoelectric conversion element 34 employs an avalanche photodiode, whose reference avalanche gain M0 satisfies 100≤M0≤500. Furthermore, the avalanche gain can be dynamically adjusted according to the incident laser reflected signal power, with an incident light power range of 0.1μW≤P_in≤0.5μW, thus adapting to the conversion requirements of reflected signals of varying intensities in long-distance scenarios. Simultaneously, the reverse bias voltage V_bias of the avalanche photodiode satisfies 50V≤V_bias≤200V, and the dark current I_dark does not exceed 10nA. Moreover, the dark current decreases as the reverse bias voltage increases. By optimizing the reverse bias voltage parameters, signal conversion efficiency is improved while reducing the impact of dark current on signal quality.

[0030] As the core component for laser signal output, the structure and parameter design of laser emitting unit 2 directly affect the stability of long-distance laser signal propagation. For example... Figure 1 As shown, the laser emitting unit 2 includes a laser emitter 21 and an emitting optical lens group 22. The laser emitter 21 is located at the starting end of the laser transmission path and is used to emit a laser signal of a specific wavelength. The emitting optical lens group 22 is located on the laser transmission path and on the laser output side of the laser emitter 21. Its main function is to collimate and expand the laser signal, thereby reducing the impact of the laser divergence angle on the accuracy of long-distance ranging.

[0031] like Figure 1 , Figure 3As shown, the emitting optical lens group 22 includes an emitting lens barrel 221, a collimating lens 222, and a beam expander lens 223. According to the laser transmission direction, the collimating lens 222 and the beam expander lens 223 are sequentially spaced inside the emitting lens barrel 221, with their optical axes collinear with the axis of the emitting lens barrel 221 to ensure no deviation of the laser signal during transmission and to guarantee the stability of the collimation and beam expansion effects. The axial distance d_beam between the collimating lens 222 and the beam expander lens 223 is the sum of the focal lengths of the two lenses, allowing a deviation of ±2mm, which facilitates the synergistic functioning of the collimating lens 222 and the beam expander lens 223.

[0032] To precisely control the long-distance propagation characteristics of the laser signal, the focal length f_col of the collimating lens 222 satisfies 5mm≤f_col≤20mm, the focal length f_beam of the beam expander lens 223 satisfies 20mm≤f_beam≤50mm, and the beam divergence angle θ of the emitting optical lens group 22 satisfies 0.1mrad≤θ≤1mrad. In this way, the beam spread area of ​​the laser signal can be controlled during long-distance transmission, avoiding excessive attenuation of the reflected signal intensity due to an excessively large beam spot, thus ensuring the effective reception of the reflected signal in long-distance scenarios.

[0033] The laser emitter 21 uses a laser diode, and its reference output optical power P_ref satisfies 5mW≤P_ref≤20mW. The operating temperature range is -10℃≤T≤60℃. By reasonably setting the output optical power and operating temperature range, the laser emitter 21 can stably output laser signals under different environmental conditions, adapting to complex application scenarios of long-distance ranging.

[0034] Signal control module 1 serves as the core control unit of the entire laser rangefinder, and its performance directly affects the accuracy and stability of distance measurement. Signal control module 1 includes a microprocessor and a signal conditioning circuit; the distance calculation formula used by the microprocessor for distance calculation is: L=(c×t_delay) / 2; Where L is the measurement distance in meters (m); c is the speed of light in a vacuum; and t_delay is the time delay from laser signal transmission to reception in seconds (s). This formula allows for the rapid and accurate calculation of the measurement distance, providing efficient computational support for long-distance ranging. The signal conditioning circuit amplifies the electrical signal output from the photoelectric converter 34, with an amplification factor A satisfying 100 ≤ A ≤ 1000. The input electrical signal amplitude range is 0.001V ≤ V_in ≤ 0.01V, and the target output signal amplitude range is 0.5V ≤ K ≤ 2V. By amplifying the weak electrical signal, the microprocessor can accurately identify and process the signal, further improving the ranging accuracy.

[0035] The technical effectiveness of the long-distance high-precision laser rangefinder of the present invention will be verified below with reference to a specific embodiment. The parameters designed in this embodiment are shown in the table below: Table 1 shows the parameter design of each core component in the embodiment. Based on the parameters of the above embodiments, and through experimental testing and verification in practical application scenarios, the technical effects of the present invention are as follows: 1) Verification of signal reception and processing effects A long-distance signal detection platform was built to capture and process laser reflection signals at a distance of 100m. The results show that the receiving optical component 32 achieves a convergence efficiency of over 90% for the laser reflection signal, and the aberration suppression lens 322 achieves a spherical aberration suppression rate of ≥85% and a chromatic aberration suppression rate of ≥80%, significantly better than the convergence efficiency (around 75%) and aberration suppression rate (spherical aberration suppression rate ≤70%, chromatic aberration suppression rate ≤65%) of existing three-lens combinations. This indicates that the receiving optical component 32 has excellent convergence and aberration suppression capabilities for weak signals at long distances, effectively avoiding laser reflection signal offset and attenuation caused by aberrations, thus ensuring accurate focusing and signal conversion. Simultaneously, the multi-layer coated interference filter 33 achieves a filtration rate of ≥98% for ambient stray light, the avalanche photodiode 34 achieves a conversion accuracy of over 95% for weak signals, and the signal conditioning circuit provides stable amplification of the electrical signal with an output signal amplitude fluctuation of ≤±0.05V, ensuring high-quality signal reception and processing in long-distance scenarios.

[0036] 2) Verification of laser emission and propagation effects The laser spot at 200m was detected using a laser beam quality analyzer. The measured laser divergence angle θ = 0.6mrad, which meets the design requirement of 0.1mrad≤θ≤1mrad. The spot diameter at 200m is 120mm, and the spot uniformity reaches 93%. Comparative experiments show that the spot diameter of existing laser emitting units at the same distance is 180-220mm, and the spot uniformity is only about 80%. The laser emitting unit 2 of this invention effectively improves the stability of long-distance propagation of laser signals and avoids excessive attenuation of reflected signal intensity due to excessively large or uneven spot size.

[0037] 3) Distance measurement accuracy verification In an open outdoor setting, three typical long-distance measurement distances of 100m, 150m, and 200m were selected. 100 repeated measurements were performed on a standard length target, and the measurement error data are recorded in the table below. Table 2 Comparison of ranging errors at different measurement distances Experimental results show that even with conventional parameters, the ranging error of this invention is close to the design requirements; after parameter optimization, the ranging error meets the design standards for each distance, fully satisfying the high-precision requirements for long-distance measurement in fields such as long-distance surveying, power line inspection, and security monitoring.

[0038] 4) Environmental adaptability verification Ranging tests were conducted on a standard target at a distance of 200m under different lighting conditions (strong light, weak light, and cloudy / rainy weather) and temperature environments (-10℃ to 60℃). The results show that the ranging error fluctuation under strong light and cloudy / rainy conditions is ≤0.03mm, and the error drift due to temperature changes is ≤0.02mm, far superior to the error fluctuation (≤0.08mm) and temperature drift (≤0.05mm) levels of existing technologies. This effect is attributed to the light-absorbing coating (reflectivity) on the inner wall of the receiving lens tube 31. The synergistic effect of the multi-layer coated interference filter 33 (stray light filtration rate ≥98%) and the wide operating temperature range (-10℃~60℃) of the laser emitter 21 effectively reduces the impact of complex environmental factors on measurement accuracy.

[0039] Actual testing and application verification show that the long-distance high-precision laser rangefinder of the present invention has high ranging accuracy and strong environmental adaptability in long-distance measurement, and can meet the high-precision measurement needs of fields such as long-distance surveying, power line inspection, and security monitoring.

[0040] This invention constructs a complete long-distance, high-precision ranging system through structural innovation and parameter optimization of the laser receiving unit 3 and the laser emitting unit 2, combined with the collaborative control of the signal control module 1. The four-lens collaborative correction structure and complementary parameter matching of the receiving optical component 32 effectively solve the problems of insufficient signal convergence and poor aberration suppression in existing technologies at long distances. The optimized design of the emitting optical lens group 22 ensures a low divergence angle and high uniformity of the laser signal, adapting to the needs of long-distance propagation. The precise calculation and signal conditioning functions of the signal control module 1 further improve the accuracy and stability of the ranging. The collaborative work between the modules provides comprehensive technical support for long-distance, high-precision ranging.

[0041] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily 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 invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A long-range, high-precision laser rangefinder, comprising a signal control module, a laser emitting unit, and a laser receiving unit; the signal control module is electrically connected to the laser emitting unit and the laser receiving unit respectively, to achieve coordinated operation of transmission control, signal reception, and distance calculation, characterized in that, The laser receiving unit includes a receiving lens barrel and receiving optical components, stray light filters, and photoelectric conversion components arranged sequentially along the laser reflection signal transmission direction; the optical axes of the receiving optical components, the stray light filters, and the photoelectric conversion components are collinear, and all three are assembled inside the receiving lens barrel; The receiving optical component is a multi-lens cooperative correction structure, including a condenser lens, an aberration suppression lens, a focusing lens, and a gain compensation lens arranged sequentially along the laser reflection signal transmission direction; the refractive indices of the condenser lens, the aberration suppression lens, the focusing lens, and the gain compensation lens satisfy a complementary fit relationship with the Abbe constant. (Nd1×Vd1+Nd2×Vd2+Nd3×Vd3+Nd4×Vd4) / 4≤T; In the formula, Nd1 is the refractive index of the condenser lens, and Vd1 is the Abbe constant of the condenser lens; Nd2 is the refractive index of the aberration suppression lens, and Vd2 is the Abbe constant of the aberration suppression lens; Nd3 is the refractive index of the focusing lens, and Vd3 is the Abbe constant of the focusing lens; Nd4 is the refractive index of the gain compensation lens, and Vd4 is the Abbe constant of the gain compensation lens; T is the adaptation threshold, and 85≤T≤95; The axial distances between the condensing lens and the aberration-suppressing lens, the axial distances between the aberration-suppressing lens and the focusing lens, and the axial distances between the focusing lens and the gain-compensating lens all satisfy the focal length coordination formula: d_adj=β×[α×f_prev+(1-α)×f_next]; In the formula, d_adj represents the axial distance between the condenser lens and the aberration suppression lens, the axial distance between the aberration suppression lens and the focusing lens, and the axial distance between the focusing lens and the gain compensation lens, respectively; α is the focal length weighting coefficient, and 0.4≤α≤0.6; when calculating the distance between the condenser lens and the aberration suppression lens, f_prev is the focal length of the condenser lens, and f_next is the focal length of the aberration suppression lens; when calculating the distance between the aberration suppression lens and the focusing lens, f_prev is the focal length of the aberration suppression lens, and f_next is the focal length of the focusing lens; when calculating the distance between the focusing lens and the gain compensation lens, f_prev is the focal length of the focusing lens, and f_next is the focal length of the gain compensation lens; β is the coordination coefficient, and 0.05≤β≤0.

12.

2. The long-distance high-precision laser rangefinder according to claim 1, characterized in that, The stray light filter is a multi-layer coated interference filter, and its reference transmittance is... satisfy Furthermore, only laser reflection signals with wavelengths ranging from 0.9μm to λ to 1.6μm are allowed to pass through.

3. The long-distance high-precision laser rangefinder according to claim 2, characterized in that, The number of coating layers n of the multilayer coated interference filter satisfies 5 layers ≤ n ≤ 15 layers, the average thickness d_avg of all coating layers satisfies 50nm ≤ d_avg ≤ 200nm, and the thickness deviation of each coating layer does not exceed 5% of the average thickness.

4. The long-distance high-precision laser rangefinder according to claim 3, characterized in that, The reverse bias voltage V_bias of the photoelectric conversion device satisfies 50V≤V_bias≤200V, the dark current I_dark does not exceed 10nA, and the dark current decreases as the reverse bias voltage increases.

5. The long-distance high-precision laser rangefinder according to claim 1, characterized in that, The photoelectric conversion device adopts an avalanche photodiode, whose reference avalanche gain M0 satisfies 100≤M0≤500, and the avalanche gain is dynamically adjusted according to the incident laser reflected signal light power, with the incident light power range being 0.1μW≤P_in≤0.5μW.

6. The long-distance high-precision laser rangefinder according to claim 1, characterized in that, The laser emitting unit includes a laser diode and an emitting optical lens group. The reference output optical power P_ref of the laser diode satisfies 5mW≤P_ref≤20mW, and the operating temperature range is -10℃≤T≤60℃.

7. The long-distance high-precision laser rangefinder according to claim 1, characterized in that, The inner wall of the receiving lens tube is provided with a light-absorbing coating, and the reflectivity of the light-absorbing coating is... The thickness h satisfies 10μm≤h≤50μm.

8. The long-distance high-precision laser rangefinder according to claim 1, characterized in that, The signal control module includes a microprocessor and a signal conditioning circuit; the distance calculation formula used by the microprocessor when performing distance calculation is as follows: L=(c×t_delay) / 2; Where L is the measurement distance in meters; c is the speed of light in a vacuum; t_delay is the time delay from laser signal transmission to reception in seconds; the signal conditioning circuit amplifies the electrical signal output by the photoelectric converter, with the amplification factor A satisfying 100 ≤ A ≤ 1000, the input electrical signal amplitude range being 0.001V ≤ V_in ≤ 0.01V, and the target output signal amplitude range being 0.5V ≤ K ≤ 2V.

9. The long-distance high-precision laser rangefinder according to claims 1-8, characterized in that, The emitting optical lens group includes a collimating lens and a beam expander arranged sequentially along the laser output direction; the focal length f_col of the collimating lens satisfies 5mm≤f_col≤20mm, the focal length f_beam of the beam expander satisfies 20mm≤f_beam≤50mm, the axial distance d_beam between the collimating lens and the beam expander is the sum of the focal lengths of the two lenses, with a tolerance of ±2mm; the beam divergence angle θ of the emitting optical lens group satisfies 0.1mrad≤θ≤1mrad.

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