Aberration-optimized optical compensation laser rangefinder

Abstract

The application relates to the technical field of laser ranging, in particular to an aberration-optimized optical compensation laser range finder. A laser receiving module comprises a receiving lens group, a filter and a photoelectric sensor; the receiving lens group, the filter and the photoelectric sensor are arranged in sequence along the transmission direction of a laser reflection signal, and the optical axes are kept collinear. The receiving lens group is composed of a front converging lens, a middle correction lens and a rear focusing lens arranged in sequence along the transmission direction of the laser reflection signal, and the refractive indexes and the Abbe constant of the three are set to a unified numerical range; the axial spacing between the front converging lens and the middle correction lens and the axial spacing between the middle correction lens and the rear focusing lens are reasonably limited, and the comprehensive focal length of the receiving lens group calculated by an optical lens combination formula is matched, so that the light condensing function of the front converging lens, the aberration correction function of the middle correction lens and the signal focusing function of the rear focusing lens are complementary and linked, thereby effectively inhibiting the spherical aberration and chromatic aberration in the optical system.

Description

Technical Field

[0001] This invention relates to the field of laser ranging technology, and in particular to an aberration-optimized optically compensated laser rangefinder. Background Technology

[0002] In fields such as industrial assembly, precision manufacturing, and microelectronics testing, it is often necessary to perform high-precision ranging on short-distance targets within 10m, and the measurement error must be controlled within ±0.1mm to ensure the assembly accuracy of products or the reliability of test results.

[0003] The main optical component of a short-range laser rangefinder is the laser receiving module, and the design of its receiving lens group directly determines the ranging accuracy. Currently, most laser rangefinders on the market use a single lens or a combination of two lenses in their receiving lens group. While a single lens is simple in structure and low in cost, it is limited by its optical characteristics and cannot simultaneously suppress spherical aberration and chromatic aberration. Although a combination of two lenses can optimize aberrations to some extent, it is still difficult to control aberrations within the range required for high-precision ranging due to limitations in parameter matching. In particular, when the refractive index deviation of the receiving lens exceeds 0.005 and the Abbe constant deviates from the 30-50 range, the impact of aberrations on accuracy will be further amplified, causing the ranging error to exceed the standard and failing to meet the needs of industrial precision measurement.

[0004] Furthermore, traditional laser rangefinder distance measurement error analysis often focuses solely on the time measurement error of the signal processing module or the divergence angle error of the laser emission, neglecting the crucial impact of aberrations in the receiving lens group on ranging accuracy. In fact, in short-range scenarios, aberration-induced spot shifts directly lead to deviations in the receiving position of the photoelectric sensor for the laser reflection signal, thus translating into distance measurement error. This has become a core bottleneck restricting the improvement of accuracy in short-range, high-precision laser rangefinders.

[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 an aberration-optimized optically compensated laser rangefinder, which aims to solve the problem that the receiving lens group in the existing design cannot effectively suppress aberrations, and the error analysis ignores the influence of aberrations, resulting in excessive short-distance ranging accuracy and difficulty in meeting the needs of industrial precision measurement.

[0007] This invention relates to an aberration-optimized optically compensated laser rangefinder, comprising a laser receiving module, a signal processing module, and a laser emitting optical path module; the signal processing module is electrically connected to the laser emitting optical path module and the laser receiving module, respectively. The laser receiving module includes a laser receiving lens barrel, a receiving lens group, a filter, and a photoelectric sensor; the receiving lens group, the filter, and the photoelectric sensor are installed sequentially and at intervals inside the laser receiving lens barrel along the transmission direction of the laser reflected signal, and the optical axes of the three are collinear; The receiving lens group consists of a front converging lens, a middle correcting lens, and a rear focusing lens, arranged sequentially along the transmission direction of the laser reflected signal. The refractive index Nd of the front converging lens, the middle correcting lens, and the rear focusing lens all satisfy 1.6≤Nd≤1.8, and the Abbe constant Vd of all satisfy 30≤Vd≤50. The combined focal length F of the receiving lens group rec Satisfies the optical lens combination formula: Where f1 is the focal length of the front converging lens, f2 is the focal length of the center correcting lens, and f3 is the focal length of the rear focusing lens; d 12 d is the axial distance between the front converging lens and the center correcting lens, and its value ranges from 0.8 mm to 1.2 mm; 23 This is the axial distance between the center correction lens and the rear focusing lens, with a value ranging from 0.6 mm to 1.0 mm. The distance measurement error ΔL of the laser rangefinder satisfies the mathematical model: Where C is the speed of laser propagation in vacuum, Δt is the time measurement error of the signal processing module, L is the measurement distance of the laser rangefinder, θ is the laser divergence angle of the laser emitting optical path module, k is the spot offset coefficient, ranging from 0.1 to 0.2, λ is the laser emission wavelength of the laser emitting optical path module, and Δn is the refractive index deviation of the receiving lens group; and when the measurement distance is ≤10m, the distance measurement error is... .

[0008] As a further improvement to the technical solution disclosed in this invention, the front converging lens is a biconvex lens with a radius of curvature r1 satisfying 6mm≤r1≤8mm and a center thickness d1 satisfying 1.2mm≤d1≤1.8mm; the middle correcting lens is a plano-convex lens with the convex surface facing the incident end, a radius of curvature r2 satisfying 10mm≤r2≤14mm and a center thickness d2 satisfying 0.8mm≤d2≤1.2mm; and the rear focusing lens is a plano-concave lens with the concave surface facing the filter, a radius of curvature r3 satisfying -12mm≤r3≤-8mm and a center thickness d3 satisfying 0.6mm≤d3≤1.0mm.

[0009] As a further improvement to the technical solution disclosed in this invention, the laser emission optical path module includes a laser generator and a collimating beam expander group; the laser generator is located at the starting end of the laser transmission path; the collimating beam expander group is located on the laser transmission path and on the laser output side of the laser generator; the collimating beam expander group includes a laser emission tube, an incident lens, a beam expander lens, and an exit lens; the incident lens, beam expander lens, and exit lens are sequentially and spaced apart inside the laser emission tube along the laser transmission direction, and the optical axes of the three are all collinear with the axis of the laser emission tube; and the axial distance d between the incident lens and the beam expander lens is... 45 The axial distance d between the beam expander lens and the exiting lens is 0.5 mm to 0.9 mm. 56 The value ranges from 0.7 mm to 1.1 mm; the laser divergence angle θ of the collimating beam expander group satisfies the formula: θ = 2arctan[D] out / (2f coll )]; where D out f is the effective aperture of the exit lens. coll The combined focal length of the collimating and beam-expanding lens group is θ≤0.5mrad.

[0010] As a further improvement to the technical solution disclosed in this invention, the incident lens is a plano-convex lens with its convex surface facing the laser generator. The refractive index Nd1 satisfies 1.55≤Nd1≤1.75, the Abbe constant Vd1 satisfies 35≤Vd1≤55, the radius of curvature r4 satisfies 5mm≤r4≤7mm, and the center thickness d4 satisfies 1.0mm≤d4≤1.5mm.

[0011] As a further improvement to the technical solution disclosed in this invention, the beam expander lens is a biconcave lens with a refractive index Nd2 satisfying 1.58≤Nd2≤1.78, an Abbe constant Vd2 satisfying 32≤Vd2≤52, a radius of curvature r5 satisfying -9mm≤r5≤-7mm, r6 satisfying -11mm≤r6≤-9mm, and a center thickness d5 satisfying 0.5mm≤d5≤0.9mm; the beam expansion ratio M of the collimating beam expander group satisfies the formula: M=f out / f in , where f out f is the focal length of the exit lens. in Let M be the focal length of the incident lens, and 1.8 ≤ M ≤ 2.5.

[0012] As a further improvement to the technical solution disclosed in this invention, the exit lens is a biconvex lens with a refractive index Nd3 satisfying 1.60≤Nd3≤1.80, an Abbe constant Vd3 satisfying 38≤Vd3≤58, a radius of curvature r7 satisfying 12mm≤r7≤16mm, r8 satisfying -10mm≤r8≤-8mm, and a center thickness d6 satisfying 1.1mm≤d6≤1.6mm.

[0013] As a further improvement to the technical solution disclosed in this invention, the effective focal length f of the collimating and beam-expanding lens group... coll Satisfying 15mm≤f coll ≤20mm, the uniformity of the laser spot after collimation and beam expansion is ≥92%.

[0014] As a further improvement to the technical solution disclosed in this invention, the inner wall of the laser receiving lens barrel is provided with a light-shielding coating; the visible light reflectivity of the light-shielding coating is ≤5%, and the infrared light reflectivity is ≤3%; the aberration correction coefficient δ of the receiving lens group satisfies the formula: Wherein, k1 is the aberration weighting coefficient of the front converging lens, with a value of 0.5 to 0.7; k2 is the aberration weighting coefficient of the center correcting lens, with a value of 0.3 to 0.5; k3 is the aberration weighting coefficient of the rear focusing lens, with a value of 0.4 to 0.6; Δn1, Δn2, and Δn3 are the refractive index deviations of the front converging lens, center correcting lens, and rear focusing lens, respectively, and none of them are greater than 0.005; d1, d2, and d3 are the center thicknesses of the front converging lens, center correcting lens, and rear focusing lens, respectively, and none of them have a thickness deviation greater than 0.01 mm.

[0015] As a further improvement to the technical solution disclosed in this invention, the filter is a narrowband filter, and its center wavelength is consistent with the laser emission wavelength of the laser emission optical path module, with a bandwidth ≤10nm, transmittance ≥90%, and ambient stray light cutoff rate ≥99%.

[0016] In practical applications, the aberration-optimized optically compensated laser rangefinder disclosed in this invention can achieve at least the following beneficial technical effects, specifically: 1) The receiving lens group is arranged sequentially along the transmission direction of the laser reflected signal, in the order of front converging lens, middle correcting lens, and rear focusing lens. The refractive index and Abbe constant of the front converging lens, middle correcting lens, and rear focusing lens are all limited to a uniform range to ensure consistent optical characteristics. Furthermore, reasonable axial spacing is set between the front converging lens and the middle correcting lens, and between the middle correcting lens and the rear focusing lens. Combined with the comprehensive focal length calculated using the optical lens combination formula, the light-gathering function of the front converging lens, the aberration correction function of the middle correcting lens, and the signal focusing function of the rear focusing lens complement each other, effectively suppressing spherical aberration and chromatic aberration, and providing stable optical support for ranging accuracy. 2) The distance measurement error model incorporates the time measurement error of the signal processing module, the laser divergence angle of the laser emitting optical path module, and the refractive index deviation of the receiving lens group into a unified calculation system. That is, the laser emitting optical path module achieves precise control of the laser divergence angle through parameter design, which is linked with the control of the refractive index deviation by the receiving lens group to reduce the deviation in the laser propagation and signal reception process; the signal processing module ensures the accuracy of time measurement, and works together with the aberration optimization effect of the optical module to avoid the impact of fluctuations in a single parameter on the overall accuracy. 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 aberration-optimized optically compensated laser rangefinder disclosed in this invention.

[0019] Figure 2 This is a schematic diagram of the laser receiving module in the aberration-optimized optical compensation laser rangefinder disclosed in this invention.

[0020] Figure 3 This is a schematic diagram of the laser emission optical path module in the aberration-optimized optical compensation laser rangefinder disclosed in this invention.

[0021] 1-Laser receiving module; 11-Laser receiving lens barrel; 12-Receiving lens group; 121-Front converging lens; 122-Center correction lens; 123-Rear focusing lens; 13-Filter; 14-Photoelectric sensor; 2-Signal processing module; 3-Laser emitting optical path module; 31-Laser generator; 32-Collimating and beam expanding lens group; 321-Laser emitting lens barrel; 322-Incident lens; 323-Beam expanding lens; 324-Outgoing lens. Detailed Implementation

[0022] The present invention will be further described in detail below with reference to specific embodiments. For example... Figure 1As shown, the laser rangefinder disclosed in this invention is mainly used for high-precision measurement scenarios within a short distance of 10m. It primarily consists of a laser receiving module 1, a signal processing module 2, and a laser emitting optical path module 3. The signal processing module 2 is electrically connected to both the laser emitting optical path module 3 and the laser receiving module 1, thereby enabling coordinated operation of laser emission timing control, reflected signal reception, and distance calculation. The laser receiving module 1 and the laser emitting optical path module 3 are arranged in parallel and are both electrically connected to the signal processing module 2.

[0023] As the core component for receiving and processing laser reflection signals, laser receiver module 1's internal structure must meet the requirements of signal transmission stability and accuracy. Specifically, for example... Figure 1 , Figure 2 As shown, the laser receiving module 1 includes a laser receiving lens barrel 11, a receiving lens group 12, a filter 13, and a photoelectric sensor 14. According to the transmission direction of the laser reflected signal, the receiving lens group 12, the filter 13, and the photoelectric sensor 14 are installed sequentially and spaced apart inside the laser receiving lens barrel 11, 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 and aberration control of the laser reflection signal, the receiving lens group 12 adopts a three-stage lens combination design, consisting of a front converging lens 121, a middle correcting lens 122, and a rear focusing lens 123, arranged sequentially along the transmission direction of the laser reflection signal. The front converging lens 121 primarily performs the initial focusing function of the laser reflection signal, the middle correcting lens 122 corrects aberrations generated during transmission, and the rear focusing lens 123 precisely focuses the corrected signal onto the photosensitive surface of the photoelectric sensor 14. These three lenses complement each other to form a synergistic effect. Furthermore, to ensure stable performance of this synergistic effect, the refractive index Nd of the front converging lens 121, the middle correcting lens 122, and the rear focusing lens 123 all satisfy 1.6 ≤ Nd ≤ 1.8, and the Abbe constant Vd of all satisfy 30 ≤ Vd ≤ 50. This ensures the compatibility of the optical characteristics of the front converging lens 121, the middle correcting lens 122, and the rear focusing lens 123, avoiding aberration control failure due to parameter differences.

[0025] At the same time, the combined focal length F of the receiving lens group 12 rec A specific optical lens combination formula must be met to precisely control the convergence and focusing effect of the signal. The formula is as follows: In the above formula, f1 is the focal length of the front converging lens 121, f2 is the focal length of the center correcting lens 122, and f3 is the focal length of the rear focusing lens 123; d 12d is the axial distance between the front converging lens 121 and the center correcting lens 122, and its value ranges from 0.8 mm to 1.2 mm; 23 The axial distance between the center correction lens 122 and the rear focusing lens 123 ranges from 0.6 mm to 1.0 mm. By combining the calculation of the comprehensive focal length formula, the light-gathering function of the front converging lens 121, the aberration correction function of the center correction lens 122, and the signal focusing function of the rear focusing lens 123 can be linked together to effectively suppress spherical aberration and chromatic aberration, providing stable optical support for ranging accuracy.

[0026] As a further optimization of the receiving lens group 12, the front converging lens 121 adopts a biconvex lens structure with a radius of curvature r1 satisfying 6mm≤r1≤8mm and a center thickness d1 satisfying 1.2mm≤d1≤1.8mm, which helps to improve the efficiency and uniformity of initial light focusing; the middle correction lens 122 adopts a plano-convex lens structure with the convex surface facing the incident end, a radius of curvature r2 satisfying 10mm≤r2≤14mm, and a center thickness d2 satisfying 0.8mm≤d2≤1.2mm, to maximize its aberration correction capability; the rear focusing lens 123 is a plano-concave lens with the concave surface facing the filter 13, a radius of curvature r3 satisfying -12mm≤r3≤-8mm, and a center thickness d3 satisfying 0.6mm≤d3≤1.0mm, which can ensure that the corrected signal is accurately focused onto the photoelectric sensor 14.

[0027] In addition, the inner wall of the laser receiving lens barrel 11 is provided with a light-shielding coating, and its visible light reflectivity is ≤5% and infrared light reflectivity is ≤3%. This can effectively reduce stray light reflection on the inner wall of the laser receiving lens barrel 11, avoid stray light interference with the signal received by the photoelectric sensor 14, and further improve the signal purity.

[0028] To quantify the aberration control effect of the receiving lens group 12, its aberration correction coefficient δ is defined to satisfy the following formula: In the formula, k1 is the aberration weighting coefficient of the front converging lens 121, with a value of 0.5 to 0.7; k2 is the aberration weighting coefficient of the intermediate correcting lens 122, with a value of 0.3 to 0.5; k3 is the aberration weighting coefficient of the rear focusing lens 123, with a value of 0.4 to 0.6; Δn1, Δn2, and Δn3 are the refractive index deviations of the front converging lens 121, intermediate correcting lens 122, and rear focusing lens 123, respectively, and none of them are greater than 0.005; d1, d2, and d3 are the center thicknesses of the front converging lens 121, intermediate correcting lens 122, and rear focusing lens 123, respectively, and none of them have a thickness deviation greater than 0.01 mm. By calculating and controlling the aberration correction coefficients, the aberration control capability of the receiving lens group 12 can be ensured to remain stable within the preset range, providing a clear basis for mass production and quality inspection.

[0029] In the laser receiving module 1, the selection of filter 13 is also crucial to signal quality. It is a narrowband filter with a center wavelength that is consistent with the laser emission wavelength of the laser emitting optical path module 3. The bandwidth is ≤10nm, the transmittance is ≥90%, and the ambient stray light cutoff rate is ≥99%. In this way, stray light in the environment can be accurately filtered out, allowing only the laser reflection signal of the target wavelength to pass through, further improving the accuracy of the signal received by the photoelectric sensor 14.

[0030] As the core component for laser signal output, the structure and parameter design of the laser emission optical path module 3 directly affect the propagation stability of the laser signal. For example... Figure 1 As shown, the laser emission optical path module 3 includes a laser generator 31 and a collimating beam expander group 32. The laser generator 31 is located at the starting end of the laser transmission path and is used to emit a laser signal of a specific wavelength. The collimating beam expander group 32 is located on the laser transmission path and on the laser output side of the laser generator 31. Its main function is to collimate and expand the laser signal, thereby reducing the impact of the laser divergence angle on the ranging accuracy.

[0031] like Figure 3 As shown, the collimating and beam-expanding lens assembly 32 includes a laser emitting lens tube 321, an incident lens 322, a beam-expanding lens 323, and an exiting lens 324. According to the laser transmission direction, the incident lens 322, beam-expanding lens 323, and exiting lens 324 are sequentially and spaced apart inside the laser emitting lens tube 321, with their optical axes all collinear with the axis of the laser emitting lens tube 321. This ensures that the laser signal does not deviate during transmission, guaranteeing the stability of the collimation and beam-expanding effects. The axial distance d between the incident lens 322 and the beam-expanding lens 323 is... 45 The axial distance d between the beam expander lens 323 and the exit lens 324 is 0.5mm to 0.9mm. 56 The value is 0.7mm to 1.1mm, which is conducive to the coordinated function of the incident lens 322, the beam expander lens 323 and the exit lens 324.

[0032] To precisely control the divergence of the laser signal, the laser divergence angle θ of the collimating beam expander group 32 satisfies the formula: θ = 2arctan[D] out / (2f coll )], where D out For the effective aperture of the exit lens 324, f coll The combined focal length of the collimating beam expander group 32 is set to θ ≤ 0.5 mrad. This ensures that the laser spot diffusion area is controllable within a transmission distance of up to 10 m. For example, calculated with θ = 0.5 mrad, the spot diameter at 10 m is only 5 mm, avoiding a decrease in reflected signal intensity or positional shift due to an excessively large spot. Furthermore, the effective focal length f of the collimating beam expander group 32 is... collSatisfying 15mm≤f coll With a beam size of ≤20mm, the uniformity of the laser spot after collimation and beam expansion is ≥92%, further improving the propagation stability and reflection efficiency of the laser signal.

[0033] Specific designs were made for the parameters of each lens in the collimating and beam-expanding lens group 32: such as Figure 3 As shown, the incident lens 322 is a plano-convex lens with its convex surface facing the laser generator 31. Its refractive index Nd1 satisfies 1.55 ≤ Nd1 ≤ 1.75, its Abbe constant Vd1 satisfies 35 ≤ Vd1 ≤ 55, its radius of curvature r4 satisfies 5 mm ≤ r4 ≤ 7 mm, and its center thickness d4 satisfies 1.0 mm ≤ d4 ≤ 1.5 mm. This facilitates efficient reception of the diverging laser emitted by the laser generator 31 and preliminary collimation. The beam expander lens 323 is a biconcave lens with a refractive index Nd2 satisfying 1.58 ≤ Nd2 ≤ 1.78, its Abbe constant Vd2 satisfying 32 ≤ Vd2 ≤ 52, its radius of curvature r5 (incident side) satisfying -9 mm ≤ r5 ≤ -7 mm, and r6 (emission side) satisfying -11 mm ≤ r6 ≤ -9 mm. Its center thickness d5 satisfies 0.5 mm ≤ d5 ≤ 0.9 mm. The beam expansion ratio M of the collimating beam expander group 32 satisfies the formula: M = f out / f in (where f) out f is the focal length of the exit lens 324. in The focal length of the incident lens 322 is 1.8 ≤ M ≤ 2.5. Through a reasonable beam expansion ratio design, the laser divergence angle can be further compressed. The exit lens 324 is a biconvex lens with a refractive index Nd3 satisfying 1.60 ≤ Nd3 ≤ 1.80, an Abbe constant Vd3 satisfying 38 ≤ Vd3 ≤ 58, a radius of curvature r7 satisfying 12 mm ≤ r7 ≤ 16 mm, r8 satisfying -10 mm ≤ r8 ≤ -8 mm, and a center thickness d6 satisfying 1.1 mm ≤ d6 ≤ 1.6 mm. It is used for final collimation of the expanded laser beam, ensuring that the laser is directed towards the target object with a low divergence angle.

[0034] To ensure the ranging accuracy of the entire laser rangefinder, this invention constructs a scientific mathematical model for distance measurement error. The distance measurement error ΔL of the laser rangefinder satisfies the following formula: In the formula, C is the speed of laser propagation in a vacuum (3 × 10⁻⁶). 8The time measurement error of the signal processing module 2 is Δt (which can be ≤5ps with an industrial-grade high-precision time chip), L is the measurement distance of the laser rangefinder, θ is the laser divergence angle of the laser emitting optical path module 3 (unit: rad), k is the spot offset coefficient (value 0.1~0.2, 0.1 for high-precision sensors), λ is the laser emission wavelength of the laser emitting optical path module 3 (usually 650nm or 905nm), and Δn is the refractive index deviation of the receiving lens group 12. This mathematical model incorporates the time measurement error of the signal processing module 2, the laser divergence angle of the laser emitting optical path module 3, and the refractive index deviation of the receiving lens group 12 into a unified calculation system. Through the precise control of the laser divergence angle by the laser emitting optical path module 3, the control of the refractive index deviation by the receiving lens group 12, and the guarantee of time measurement accuracy by the signal processing module 2, the three work together to avoid the impact of fluctuations in a single parameter on the overall accuracy.

[0035] The technical effectiveness of the aberration-optimized optically compensated 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 optical 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 aberration control effect An aberration detection platform was built, and the spherical aberration and chromatic aberration of the receiving lens group 12 were measured using a Zygo interferometer. The results show that the spherical aberration of the combination of the front converging lens 121, the middle correcting lens 122, and the rear focusing lens 123 is ≤0.02λ (λ=632.8nm), and the chromatic aberration is ≤0.01λ, which is far superior to the existing dual-lens combination level of ≤0.05λ and ≤0.03λ. This indicates that the receiving lens group 12 has excellent suppression capabilities for spherical aberration and chromatic aberration, and can effectively avoid laser reflection signal shift caused by aberrations, thus providing a guarantee for subsequent accurate focusing. 2) Verification of laser divergence angle and spot characteristics The laser spot at 10m was tested using a laser beam quality analyzer. When the beam expansion ratio M of the collimating beam expander group 32 was 2.5, the measured laser divergence angle θ was 0.4mrad, which meets the design requirement of θ≤0.5mrad. The diameter of the spot at 10m was 8mm, and the spot uniformity reached 94%, which is higher than the design standard (≥92%).

[0036] Comparative experiments show that the existing dual-lens beam expander scheme has a spot diameter of 12-15 mm at the same distance, and the spot uniformity is only about 85%. The collimating beam expander group 32 of the present invention effectively improves the propagation stability and reflection efficiency of the laser signal, and avoids the fluctuation of the reflected signal intensity caused by the spot being too large or uneven.

[0037] 3) Distance measurement accuracy verification In an industrial assembly scenario, three typical measurement distances of 5m, 8m, and 10m were selected. Standard length workpieces were repeatedly measured 100 times, and the measurement error data were recorded as shown in the table below. Table 2 Comparison of ranging errors at different measurement distances Experimental results show that even with conventional industrial parameters, the ranging error of this invention is close to the design requirements; after parameter optimization, the ranging error is ≤0.081mm, which fully meets the high-precision requirements for short-distance measurement within 10m in fields such as industrial assembly, precision manufacturing, and microelectronics testing.

[0038] 4) Environmental adaptability verification Distance measurement tests were conducted on a standard workpiece at a distance of 10m under different lighting conditions (strong light, weak light, indoor / outdoor switching) and temperature environments (-10℃ to 45℃). The results show that the distance measurement error fluctuation under strong light conditions is ≤0.01mm, and the error drift caused by temperature changes is ≤0.008mm, which is far superior to the existing technology's error fluctuation of ≤0.03mm and temperature drift of ≤0.02mm.

[0039] This effect is due to the synergistic effect of the light-shielding coating (visible light reflectivity ≤5%, infrared light reflectivity ≤3%) on the inner wall of the laser receiving lens tube and the narrow-band filter (ambient stray light cutoff rate ≥99%), which effectively reduces the impact of ambient stray light and temperature changes on measurement accuracy.

[0040] Actual testing and application verification show that the laser rangefinder of this invention can stably control the ranging error within ±0.1mm in short-distance measurements within 10m, has strong environmental adaptability, and can meet the high-precision measurement needs of fields such as industrial assembly, precision manufacturing, and microelectronics testing.

[0041] This invention constructs a complete high-precision ranging system through structural innovation and parameter optimization of the laser receiving module 1 and the laser emitting optical path module 3, combined with the coordinated control of the signal processing module. The three-level combination design and parameter coordination of the receiving lens group 12 effectively solve the problem of insufficient aberration suppression in the prior art; the optimized design of the collimating beam expander group 32 ensures a low divergence angle and high uniformity of the laser signal; and the three-dimensional error model including aberration errors enables precise control of ranging accuracy.

[0042] 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. An aberration-optimized optically compensated laser rangefinder, comprising a laser receiving module, a signal processing module, and a laser emitting optical path module; wherein the signal processing module is electrically connected to the laser emitting optical path module and the laser receiving module respectively; The laser receiving module includes a laser receiving lens barrel, a receiving lens group, a filter, and a photoelectric sensor; the receiving lens group, the filter, and the photoelectric sensor are sequentially and spaced apart inside the laser receiving lens barrel along the transmission direction of the laser reflected signal, and the optical axes of the three are collinear; The receiving lens group consists of a front converging lens, a middle correcting lens, and a rear focusing lens, and is arranged sequentially along the transmission direction of the laser reflection signal. Its features are: The refractive index Nd of the front converging lens, the middle correcting lens, and the rear focusing lens all satisfy 1.6≤Nd≤1.8, and the Abbe constant Vd of all satisfy 30≤Vd≤50. The combined focal length F of the receiving lens group rec Satisfies the optical lens combination formula: Where f1 is the focal length of the front converging lens, f2 is the focal length of the intermediate correcting lens, and f3 is the focal length of the rear focusing lens; d 12 d is the axial distance between the front converging lens and the center correcting lens, and its value ranges from 0.8 mm to 1.2 mm; 23 The axial distance between the intermediate correction lens and the rear focusing lens ranges from 0.6 mm to 1.0 mm. The distance measurement error ΔL of the laser rangefinder satisfies the following mathematical model: Where C is the speed of laser propagation in vacuum, Δt is the time measurement error of the signal processing module, L is the measurement distance of the laser rangefinder, θ is the laser divergence angle of the laser emitting optical path module, k is the spot offset coefficient, ranging from 0.1 to 0.2, λ is the laser emission wavelength of the laser emitting optical path module, and Δn is the refractive index deviation of the receiving lens group; and when the measurement distance is ≤10m, the distance measurement error is... .

2. The aberration-optimized optically compensated laser rangefinder according to claim 1, characterized in that, The front converging lens is a biconvex lens with a radius of curvature r1 satisfying 6mm≤r1≤8mm and a center thickness d1 satisfying 1.2mm≤d1≤1.8mm; the center correcting lens is a plano-convex lens with the convex surface facing the incident end, a radius of curvature r2 satisfying 10mm≤r2≤14mm and a center thickness d2 satisfying 0.8mm≤d2≤1.2mm; the rear focusing lens is a plano-concave lens with the concave surface facing the filter, a radius of curvature r3 satisfying -12mm≤r3≤-8mm and a center thickness d3 satisfying 0.6mm≤d3≤1.0mm.

3. The aberration-optimized optically compensated laser rangefinder according to claim 1, characterized in that, The laser emission optical path module includes a laser generator and a collimating beam expander assembly. The laser generator is located at the starting end of the laser transmission path. The collimating beam expander assembly is located on the laser transmission path and on the laser output side of the laser generator. The collimating beam expander assembly includes a laser emission tube, an incident lens, a beam expander lens, and an exit lens. The incident lens, the beam expander lens, and the exit lens are sequentially spaced inside the laser emission tube along the laser transmission direction, and their optical axes are all collinear with the axis of the laser emission tube. The axial distance d between the incident lens and the beam expander lens is... 45 The axial distance d between the beam expander lens and the exiting lens is 0.5 mm to 0.9 mm, with a value ranging from 0.5 mm to 0.9 mm. 56 The value ranges from 0.7 mm to 1.1 mm; the laser divergence angle θ of the collimating beam expander group satisfies the formula: θ = 2arctan[D] out / (2f coll )]; where D out f is the effective aperture of the exit lens. coll The combined focal length of the collimating and beam-expanding lens group is θ≤0.5mrad.

4. The aberration-optimized optically compensated laser rangefinder according to claim 3, characterized in that, The incident lens is a plano-convex lens with its convex surface facing the laser generator. The refractive index Nd1 satisfies 1.55≤Nd1≤1.75, the Abbe constant Vd1 satisfies 35≤Vd1≤55, the radius of curvature r4 satisfies 5mm≤r4≤7mm, and the center thickness d4 satisfies 1.0mm≤d4≤1.5mm.

5. The aberration-optimized optically compensated laser rangefinder according to claim 3, characterized in that, The beam expander lens is a biconcave lens with a refractive index Nd2 satisfying 1.58 ≤ Nd2 ≤ 1.78, an Abbe constant Vd2 satisfying 32 ≤ Vd2 ≤ 52, a radius of curvature r5 satisfying -9 mm ≤ r5 ≤ -7 mm, r6 satisfying -11 mm ≤ r6 ≤ -9 mm, and a center thickness d5 satisfying 0.5 mm ≤ d5 ≤ 0.9 mm. The beam expansion ratio M of the collimating beam expander group satisfies the formula: M = f out / f in , where f out f is the focal length of the exit lens. in Let M be the focal length of the incident lens, and 1.8 ≤ M ≤ 2.

5.

6. The aberration-optimized optically compensated laser rangefinder according to claim 3, characterized in that, The exiting lens is a biconvex lens with a refractive index Nd3 satisfying 1.60≤Nd3≤1.80, an Abbe constant Vd3 satisfying 38≤Vd3≤58, a radius of curvature r7 satisfying 12mm≤r7≤16mm, r8 satisfying -10mm≤r8≤-8mm, and a center thickness d6 satisfying 1.1mm≤d6≤1.6mm.

7. The aberration-optimized optically compensated laser rangefinder according to claim 3, characterized in that, The effective focal length f of the collimating and beam-expanding lens group coll Satisfying 15mm≤f coll ≤20mm, the uniformity of the laser spot after collimation and beam expansion is ≥92%.

8. The aberration-optimized optically compensated laser rangefinder according to claim 2, characterized in that, The inner wall of the laser receiving lens tube is provided with a light-shielding coating; the visible light reflectivity of the light-shielding coating is ≤5%, and the infrared light reflectivity is ≤3%; the aberration correction coefficient δ of the receiving lens group satisfies the formula: Wherein, k1 is the aberration weighting coefficient of the front converging lens, with a value of 0.5 to 0.7; k2 is the aberration weighting coefficient of the center correcting lens, with a value of 0.3 to 0.5; k3 is the aberration weighting coefficient of the rear focusing lens, with a value of 0.4 to 0.6; Δn1, Δn2, and Δn3 are the refractive index deviations of the front converging lens, the center correcting lens, and the rear focusing lens, respectively, and none of them are greater than 0.005; d1, d2, and d3 are the center thicknesses of the front converging lens, the center correcting lens, and the rear focusing lens, respectively, and none of them have a thickness deviation greater than 0.01 mm.

9. The aberration-optimized optically compensated laser rangefinder according to claim 1, characterized in that, The filter is a narrowband filter, and its center wavelength is consistent with the laser emission wavelength of the laser emission optical path module. The bandwidth is ≤10nm, the transmittance is ≥90%, and the ambient stray light cutoff rate is ≥99%.

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