A laser scanning lens with large receiving range and high energy receiving efficiency and its application

Abstract

The present invention proposes a laser scanning lens with a large receiving range and high energy receiving efficiency and its application, belonging to the field of optical lenses. It is composed of a telescopic system and a focusing system. The entrance pupil of the lens and the exit pupil of the lens are conjugate. The light receiving surface is located at the position of the entrance pupil of the lens, and the photosensitive surface of the photodetector is located at the position of the exit pupil of the lens. The entrance pupil diameter D1 and the exit pupil diameter D2 of the telescopic system satisfy: 100 < D1 / D2 < 1000 and D ≥ 35 mm. The front group focal length F1 and the entrance pupil diameter D1 of the telescopic system satisfy: 1 < F1 / D1 < 3. The rear group focal length F2 of the telescopic system and the front group focal length F1 satisfy: 10 < F1 / F2 < 100. With the conjugate design of the entrance pupil and the exit pupil, this laser scanning lens can achieve 100% light reception within the non-blocked range of the entrance pupil diameter in the case of coaxial transceiver, greatly ensuring the light energy receiving efficiency in the medium and long distances, and has important application value in large-range and high-precision laser three-dimensional scanning.

Description

Technical Field

[0001] The present invention relates to the field of optical lenses, and specifically to a laser scanning lens with a large receiving range and high energy receiving efficiency and applications thereof. Background Art

[0002] Large-scene high-precision laser 3D scanning technology is a means of efficiently acquiring large-scale 3D spatial point cloud data. It can achieve real, three-dimensional, and high-precision mapping from physical space to digital space. It has been widely used in many important fields such as intelligent construction, smart cities, digital surveying and mapping, and industrial inspection.

[0003] Large-scene high-precision laser 3D scanning technology usually adopts the phase method or pulse method laser ranging principle. The laser is emitted from the transmitting optical system to the target object, collected by the receiving optical system after diffuse reflection, and converted into an electrical signal by the photoelectric detector. Signal processing and solution are then performed to finally obtain the target object ranging result.

[0004] The optical lenses in common laser 3D scanning systems currently usually adopt an object-image conjugate design and structure. Its advantages are low design difficulty and easy implementation, but there is a problem that the image distance changes in real time with the object distance. Since the target object can change randomly from close distance to long distance, and the photodetector is fixed in position after installation, the system can only ensure that the return light energy in a smaller range is 100% received within the entire measurement range. Only part of the energy in other large ranges can be received, resulting in a huge waste of return light energy, which has a very adverse impact on the measurement accuracy and measurement range of the system. Summary of the Invention

[0005] In response to the problem of low light-collecting efficiency of optical lenses in common laser three-dimensional scanning systems, the present invention proposes a laser scanning lens with a large receiving range and high energy receiving efficiency and its application. The laser scanning lens adopts a design structure in which the entrance and exit pupils are conjugated, which improves the energy receiving efficiency and can realize large-range, high-precision laser three-dimensional scanning.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a laser scanning lens with a large receiving range and high energy receiving efficiency, characterized in that the laser scanning lens is composed of a telescopic system and a focusing system, the lens entrance pupil and the lens exit pupil are conjugate, the light-collecting surface is located at the lens entrance pupil position, and the photodetector light-sensing surface is located at the lens exit pupil position;

[0008] The telescopic system described above includes a first aspherical lens, an annular planar mirror, a spherical mirror, a 90° turning prism, and a spherical lens that are sequentially arranged on the optical axis along the object side to the image side. The spherical mirror is fixed on the image side surface of the first aspherical lens, and the annular planar mirror is located between the image side surface of the first aspherical lens and the object side surface of the 90° turning prism. A 45° central occlusion reflecting prism is also fixed at the center of the object side surface of the first aspherical lens.

[0009] The entrance pupil diameter D1 of the telescopic system and the exit pupil diameter D2 of the telescopic system satisfy: 100 < D1 / D2 < 1000 and D1 ≥ 35 mm. The front group focal length F1 of the telescopic system except the spherical lens and the entrance pupil diameter D1 satisfy: 1 < F1 / D1 < 3. The focal length F2 of the spherical lens in the telescopic system and the front group focal length F1 satisfy: 10 < F1 / F2 < 100.

[0010] As a preference of the present invention, the exit pupil diameter D2 of the telescopic system is equal to the entrance pupil diameter of the focusing system, and the exit pupil diameter D3 of the focusing system is equal to the photosensitive surface diameter of the photodetector, and satisfy: 2 < D2 / D3 < 12.

[0011] As a preference of the present invention, the diameter d0 of the 45° central occlusion reflecting prism satisfies: d0 / D1 < 1 / 5.

[0012] As a preference of the present invention, in the telescopic system, the light collected by the first aspherical lens first enters the outer ring reflecting surface of the annular planar mirror after passing through the first aspherical lens, and then is reflected to the spherical mirror, and then passes through the inner ring of the annular planar mirror and enters the 90° turning prism. After deflecting the optical path by 90°, it enters the spherical lens and is focused to the focusing system.

[0013] As a preference of the present invention, the focusing system includes a narrowband filter and a second aspherical lens that are sequentially arranged on the optical axis along the object side to the image side. The air gap between adjacent components satisfies:

[0014] 0.05 ≤ d12 / D1 ≤ 2;

[0015] 0.04 ≤ d23 / D1 ≤ 1.75;

[0016] 0.05 ≤ d34 / D1 ≤ 2;

[0017] 0.01 ≤ d45 / D1 ≤ 1;

[0018] 0.01 ≤ d56 / D1 ≤ 1;

[0019] 0.05 ≤ d67 / D1 ≤ 2;

[0020] Among them, D1 is the entrance pupil diameter of the telescope system, d12 is the air gap between the first aspheric lens and the annular plane reflector, d23 is the air gap between the annular plane reflector and the spherical reflector, d34 is the air gap between the spherical reflector and the 90° folding prism, d45 is the air gap between the 90° folding prism and the spherical lens, d56 is the air gap between the spherical lens and the narrowband filter, and d67 is the air gap between the narrowband filter and the second aspheric lens.

[0021] As a preferred embodiment of the present invention, each element in the telescopic system satisfies the following relationship:

[0022] 0.1≤R1 / D1≤1, R2=∞, 0.5≤R1 / t1≤3, 0.2≤D1 / f1≤1.5;

[0023] R3=∞, 0.2≤d2out / t2≤15, 10≤d2out / d2in≤25;

[0024] 0.2≤R4 / d3≤5, 0.2≤d3 / f2≤2, 1.5≤d3 / t3≤12.5;

[0025] R5=∞, R6=∞, 0.1≤d4 / t4≤2, 0.1≤d5 / t5≤2, 0.5≤d4 / d5≤2;

[0026] 0.1≤R7 / R8≤10, 0.1≤R7 / d6≤10, 0.1≤R8 / d6≤10, 0.1≤d6 / f3≤2;

[0027] Among them, R1, R2, t1 and f1 are respectively the object side curvature radius, image side curvature radius, thickness on the optical axis and effective focal length of the first aspheric lens; R3, t2, d2out and d2in are respectively the reflecting surface curvature radius, thickness on the optical axis, outer diameter and inner diameter of the annular plane reflector; R4, d3, t3 and f2 are respectively the reflecting surface curvature radius, entrance pupil aperture, thickness on the optical axis and effective focal length of the spherical reflector; R5, R6, d4, d5, t4 and t5 are respectively the object side curvature radius, image side curvature radius, entrance pupil aperture, exit pupil aperture, thickness from the incident surface to the reflecting surface on the optical axis and thickness from the reflecting surface to the exit surface on the optical axis of the 90° folding prism; R7, R8, d6 and f3 are respectively the object side curvature radius, image side curvature radius, entrance pupil aperture, thickness on the optical axis and effective focal length of the spherical lens.

[0028] As a preferred embodiment of the present invention, the annular plane reflector and the spherical reflector satisfy the following relationship:

[0029] 0.24≤d2out / t2≤12, 10≤d2out / d2in≤22;

[0030] 0.25 ≤ R4 / d3 ≤ 4.5, 0.25 ≤ d3 / f2 ≤ 1.8, 1.75 ≤ d3 / t3 ≤ 10.5.

[0031] Preferably in the present invention, each element in the focusing system satisfies the following relationships:

[0032] R9 = ∞, R10 = ∞, 1550 - 20 nm ≤ λ ≤ 1550 + 20 nm;

[0033] 0.1 ≤ R11 / d6 ≤ 1, 0.1 ≤ R12 / d6 ≤ 1, 0.5 ≤ d6 / t6 ≤ 10, 0.2 ≤ d6 / f4 ≤ 10.5;

[0034] Wherein, R9, R10 and λ are respectively the object - side curvature radius, image - side curvature radius and wavelength of the narrow - band filter; R11, R12, d6, t6 and f4 are respectively the object - side curvature radius, image - side curvature radius, entrance pupil diameter, thickness on the optical axis and effective focal length f4 of the second aspherical lens.

[0035] Preferably in the present invention, the narrow - band filter in the telescopic system and the focusing system is made of a glass material satisfying the condition of 12 < v1 / nd1 < 20, where v1 and nd1 are respectively the d - line refractive index and Abbe number.

[0036] Preferably in the present invention, the laser emitted by the laser 3D scanner is reflected by the 45° central - obstruction reflection prism in the laser scanning lens and then incident on the surface of the target object, and the reflected light of the target object is collected by the laser scanning lens to the photodetector.

[0037] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0038] The laser scanning lens of the present invention is composed of a telescopic system and a focusing system, satisfying the relationship between the entrance pupil diameter D1 and the exit pupil diameter D2 of the telescopic system: 100 < D1 / D2 < 1000 and D ≥ 35 mm, the relationship between the front - group focal length F1 and the entrance pupil diameter D1 of the telescopic system: 1.0 < F1 / D1 < 3.0, and the relationship between the rear - group focal length F2 and the front - group focal length F1 of the telescopic system: 10.0 < F1 / F2 < 100.0; this lens adopts a design structure with conjugate entrance pupil and exit pupil, the light - receiving surface is located at the entrance pupil position, and the photosensitive surface of the photodetector is located at the exit pupil position, realizing 100% light collection of the non - blocked area within the entrance pupil diameter incident on the photosensitive surface of the photodetector. Compared with the common optical lens with conjugate object and image, when other factors such as the output light power and target reflectivity are the same, the energy reception efficiency is greatly improved, and large - range and high - precision laser 3D scanning can be achieved. Description of the Drawings

[0039] The following is a brief introduction to the drawings of the embodiment of the invention. Reading with reference to it will provide a clearer understanding of the advantages and overall structure of the present invention. Relevant people in this field can also obtain other characteristic parameters related to the present invention based on the drawings.

[0040] Figure 1 This is an overall optical path diagram of a laser scanning lens with a large receiving range and high energy receiving efficiency shown in the present invention.

[0041] Figure 2 It is a structural diagram of the application of laser scanning lens in 3D scanner.

[0042] Figure 3 This is the optical path diagram of the photosensitive surface of the photodetector when the object distance of the laser scanning lens is 100m.

[0043] Figure 4 It is the photosensitive surface of the photodetector when the object distance of the laser scanning lens is 100m.

[0044] Figure 5 This is the optical path diagram of the front end of the photodetector when the object distance of the laser scanning lens is 75m.

[0045] Figure 6 It is the photosensitive surface of the photodetector when the object distance of the laser scanning lens is 75m.

[0046] Figure 7 This is the optical path diagram of the photosensitive surface of the photodetector when the object distance of the laser scanning lens is 50m.

[0047] Figure 8 It is the photosensitive surface of the photodetector when the object distance of the laser scanning lens is 50m.

[0048] Figure 9 This is the optical path diagram of the front end of the photodetector when the object distance of the laser scanning lens is 25m.

[0049] Figure 10 It is the photosensitive surface of the photodetector when the object distance of the laser scanning lens is 25m.

[0050] Figure 11 This is the optical path diagram of the front end of the photodetector when the object distance of the laser scanning lens is 10m.

[0051] Figure 12 It is the photosensitive surface of the photodetector when the object distance of the laser scanning lens is 10m.

[0052] Figure 13 This is the optical path diagram of the front end of the photosensitive surface of the photodetector when the object distance of the laser scanning lens is 5m.

[0053] Figure 14 It is the photosensitive surface of the photodetector when the object distance of the laser scanning lens is 5m.

[0054] Figure 15 This is the optical path diagram of the front end of the photodetector when the object distance of the laser scanning lens is 1m.

[0055] Figure 16 It is the photosensitive surface of the photodetector when the object distance of the laser scanning lens is 1m.

[0056] Figure 17 It is the image plane illumination distribution diagram of the laser scanning lens under a given light source and with an object distance of 100m under occlusion.

[0057] Figure 18 It is the image plane illumination distribution diagram of the laser scanning lens at an object distance of 75m under a given light source and with shading.

[0058] Figure 19 It is the illumination distribution diagram of the laser scanning lens at an object distance of 50m under a given light source and with shading.

[0059] Figure 20 It is the image plane illumination distribution diagram of the laser scanning lens at an object distance of 25m under a given light source and with shading.

[0060] Figure 21 It is the illumination distribution diagram of the laser scanning lens at an object distance of 10m under a given light source and with shading.

[0061] Figure 22 It is the illumination distribution diagram of the laser scanning lens at an object distance of 5m under a given light source and with shading.

[0062] Figure 23 It is the illumination distribution diagram of the laser scanning lens at an object distance of 1m under a given light source and with occlusion. DETAILED DESCRIPTION

[0063] To better illustrate the advantages and features of the present invention, the present invention is described in detail below with reference to the accompanying drawings. The embodiment described is only one embodiment of the present invention, and all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0064] Reference Attachment Figure 1, the present invention provides a laser scanning lens with a large receiving range and high energy receiving efficiency. The scanning lens is an optical system composed of multiple lenses. Specifically, from the object side to the image side along the optical axis, the laser scanning lens includes: a first aspherical lens 2, an annular plane mirror 4, a spherical mirror 3, a 90° folding prism 5, a spherical lens 6, a narrow-band filter 7, and a second aspherical lens 8. In the arrangement of each component, the spherical mirror 3 is fixed on the image side surface of the first aspherical lens 2, and the annular plane mirror 4 is located between the image side surface of the first aspherical lens 2 and the object side surface of the 90° folding prism 5; the light collected by the first aspherical lens 2 first passes through the first aspherical lens 2 and then enters the outer ring reflecting surface of the annular plane mirror 4, is reflected to the spherical mirror 3, and then passes through the inner ring of the annular plane mirror 4 and enters the 90° folding prism 5. After deflecting the optical path by 90°, it enters the spherical lens 6 and is focused to the focusing system. In addition, the lens of the present invention is adapted to central occlusion, so a 45° central occlusion reflecting prism 1 is also fixed at the center of the object side surface of the first aspherical lens 2.

[0065] The entrance pupil diameter D1 of the telescopic system and the exit pupil diameter D2 of the telescopic system need to satisfy: 100 < D1 / D2 < 1000 and D1 ≥ 35 mm; the front group focal length F1 of the telescopic system and the entrance pupil diameter D1 satisfy: 1 < F1 / D1 < 3; the rear group focal length F2 of the telescopic system and the front group focal length F1 satisfy: 10 < F1 / F2 < 100. The exit pupil diameter D2 of the telescopic system is equal to the entrance pupil diameter of the focusing system, and the exit pupil diameter D3 of the focusing system is equal to the photosensitive surface diameter of the photodetector, and satisfies: 2 < D2 / D3 < 12. The diameter d0 of the 45° central occlusion reflecting prism 1 satisfies: d0 / D1 < 1 / 5, so as to ensure that the energy loss due to central occlusion is small enough.

[0066] In the present invention, the first aspherical lens 2 is a plano-convex lens, its first surface is an aspherical surface, and the second surface is a plane; the spherical lens 6 and the second aspherical lens 8 are both biconvex positive lenses, and both the front and rear surfaces are aspherical surfaces.

[0067] The functions and parameters of each component will be introduced separately below.

[0068] The object side curvature radius R1, image side curvature radius R2, entrance pupil diameter D1, thickness t1 on the optical axis, and effective focal length f1 of the aspherical lens 2 satisfy:

[0069] 0.1 ≤ R1 / D1 ≤ 1;

[0070] R2 = ∞;

[0071] 0.5 ≤ R1 / t1 ≤ 3;

[0072] 0.2 ≤ D1 / f1 ≤ 1.5.

[0073] In a preferred embodiment of the present invention, the following conditions are met:

[0074] 0.2≤R1 / D1≤0.85;

[0075] R2=∞;

[0076] 0.6≤R1 / t1≤2.8;

[0077] 0.25≤D1 / f1≤1.35.

[0078] The curvature radius R3, outer diameter d2out, inner diameter d2in, and thickness t2 on the optical axis of the annular plane reflector 4 satisfy the following conditions:

[0079] R3=∞;

[0080] 0.2≤d2out / t2≤15;

[0081] 10≤d2out / d2in≤25.

[0082] In a preferred embodiment of the present invention, the following conditions are met:

[0083] R3=∞;

[0084] 0.24≤d2out / t2≤12;

[0085] 10≤d2out / d2in≤22.

[0086] The curvature radius R4 of the reflecting surface, the entrance pupil diameter d3, the thickness t3 on the optical axis, and the effective focal length f2 of the spherical reflector 3 satisfy the following conditions:

[0087] 0.2≤R4 / d3≤5;

[0088] 0.2≤d3 / f2≤2;

[0089] 1.5≤d3 / t3≤12.5.

[0090] In a preferred embodiment of the present invention, the following conditions are met:

[0091] 0.25≤R4 / d3≤4.5;

[0092] 0.25≤d3 / f2≤1.8;

[0093] 1.75≤d3 / t3≤10.5.

[0094] The object side curvature radius R5, image side curvature radius R6, entrance pupil diameter d4, exit pupil diameter d5, thickness t4 from incident surface to reflection surface on the optical axis, and thickness t5 from reflection surface to exit surface on the optical axis of the 90° folding prism 5 satisfy the following:

[0095] R5=∞;

[0096] R6=∞;

[0097] 0.1≤d4 / t4≤2;

[0098] 0.1≤d5 / t5≤2;

[0099] 0.5≤d4 / d5≤2.

[0100] In a preferred embodiment of the present invention, the following conditions are met:

[0101] R5=∞;

[0102] R6=∞;

[0103] 0.15≤d4 / t4≤1.8;

[0104] 0.2≤d5 / t5≤2;

[0105] 0.65≤d4 / d5≤2.

[0106] The object side curvature radius R7, image side curvature radius R8, optical axis thickness t6, and effective focal length f3 of the spherical lens 6 satisfy the following conditions:

[0107] 0.1≤R7 / R8≤10;

[0108] 0.1≤R7 / d6≤10;

[0109] 0.1≤R8 / d6≤10;

[0110] 0.1≤d6 / f3≤2.

[0111] In a preferred embodiment of the present invention, the following conditions are met:

[0112] 0.15≤R7 / R8≤9;

[0113] 0.15≤R7 / d6≤9;

[0114] 0.15≤R8 / d6≤9;

[0115] 0.15≤d6 / f3≤2.

[0116] The object side curvature radius R9, image side curvature radius R10, and wavelength range λ of the narrowband filter 7 satisfy:

[0117] R9=∞;

[0118] R10=∞;

[0119] 1550-20nm≤λ≤1550+20nm.

[0120] In a preferred embodiment of the present invention, the following conditions are met:

[0121] R9=∞;

[0122] R10=∞;

[0123] 1550-15nm≤λ≤1550+15nm.

[0124] The object side curvature radius R11, image side curvature radius R12, entrance pupil diameter d6, thickness on the optical axis t6, and effective focal length f4 of the second aspheric lens 8 satisfy:

[0125] 0.1≤R11 / d6≤1;

[0126] 0.1≤R12 / d6≤1;

[0127] 0.5≤d6 / t6≤10;

[0128] 0.2≤d6 / f4≤10.5.

[0129] In a preferred embodiment of the present invention, the following conditions are met:

[0130] 0.125≤R11 / d6≤1;

[0131] 0.125≤R12 / d6≤1;

[0132] 0.5≤d6 / t6≤9;

[0133] 0.22≤d6 / f4≤10.

[0134] Between the above-mentioned components, namely, the aspheric lens 2, the spherical reflector 3, the annular plane reflector 4, the 90° folding prism 5, the spherical lens 6, the narrowband filter 7, and the second aspheric lens 8, the air spacing between adjacent components satisfies:

[0135] 0.05≤d12 / D1≤2;

[0136] 0.04≤d23 / D1≤1.75;

[0137] 0.05≤d34 / D1≤2;

[0138] 0.01≤d45 / D1≤1;

[0139] 0.01≤d56 / D1≤1;

[0140] 0.05≤d67 / D1≤2.

[0141] In a preferred embodiment of the present invention, 0.06≤d12 / D1≤1.75 is satisfied;

[0142] 0.06 ≤ d23 / D1 ≤ 1.5;

[0143] 0.05 ≤ d34 / D1 ≤ 1.75;

[0144] 0.02 ≤ d45 / D1 ≤ 1;

[0145] 0.02 ≤ d56 / D1 ≤ 1;

[0146] 0.06 ≤ d67 / D1 ≤ 1.75.

[0147] Wherein, D1 is the entrance pupil diameter of the telescopic system, d12 is the air gap between the aspherical lens 2 and the annular plane mirror 4, d23 is the air gap between the annular plane mirror 4 and the spherical mirror 3, d34 is the air gap between the spherical mirror 3 and the 90° folding prism 5, d45 is the air gap between the 90° folding prism 5 and the spherical lens 6, d56 is the air gap between the spherical lens 6 and the narrowband filter 7, and d67 is the air gap between the narrowband filter 7 and the second aspherical lens 8.

[0148] In the present invention, the entrance pupil D1 and the exit pupil D2 of the telescopic system in the laser scanning lens satisfy: 100 < D1 / D2 < 1000. It is necessary to have a sufficiently large entrance pupil diameter, which is beneficial for receiving energy and thus increasing the measurement distance. When the three-dimensional scanner is working, the target distance may change suddenly in a very short time. Therefore, the optical system is a system without moving parts. So, by adopting the pupil-to-pupil imaging method, when the target changes from near (1 - 100 m) with the position of the detector unchanged, the light energy entering the aperture of the optical system can be received by the detector.

[0149] In this embodiment, except that the second aspherical lens is made of the high refractive index material H-ZF88, all the other lenses are made of the same high-performance and low-cost H-K9L glass material. Define the d-line refractive index of the lens material as nd₁ and the Abbe number as v₁. Since the scanning lens operates in the infrared wavelength region, the glass material used satisfies 12 < v₁ / nd₁ < 20; preferably, it satisfies 14 < v₁ / nd₁ < 16.5. Satisfying this relationship is beneficial for the system to collect light of a specific wavelength, and using the same material is beneficial for improving the feasibility and industrialization of the system.

[0150] The laser scanning lens of the present invention is illustrated below using an example. The focal length, on-axis distance, radius of curvature, and on-axis thickness are expressed in millimeters. Tables 1 and 2 show the design data for the laser scanning lens, respectively listing the object-side and image-side curvature radii R of each lens and reflector, the on-axis thickness of each lens, the distance d between adjacent lenses, and the refractive index nd and Abbe number vd of the lens glass material. It should be noted that in this embodiment, both R and d are expressed in millimeters (mm).

[0151] Table 1

[0152]

[0153] The meanings of the symbols are as follows.

[0154] R: the radius of curvature of each surface in the lens;

[0155] S1~S14: various surfaces of lens elements;

[0156] S0: target object surface;

[0157] S1: object side surface of the first aspheric lens;

[0158] S2: image side surface of the first aspheric lens;

[0159] S3: annular plane reflecting surface;

[0160] S4: spherical reflecting surface;

[0161] S5: 90° folding prism incident surface;

[0162] S6: 90° folding prism exit surface;

[0163] S7: object side of the spherical lens;

[0164] S8: image side of the spherical lens;

[0165] S9: front surface of narrowband filter;

[0166] S10: rear surface of narrowband filter;

[0167] S11: object side surface of the second aspheric lens;

[0168] S12: image side surface of the second aspheric lens;

[0169] S13: object side of the detector glass cover;

[0170] S14: image side of the detector glass cover;

[0171] S1*, S11*, S12* are aspherical surfaces, and the aspherical expressions are:

[0172]

[0173] The corresponding aspheric coefficients are shown in Table 2:

[0174] Table 2

[0175]

[0176] Figure 2 The figure shows a schematic diagram of the structure of the laser scanning lens of the present invention used in a laser 3D scanner. The figure includes the laser scanning lens of the present invention, a photosensitive detector 9, a laser output fiber 10, an emission beam collimating lens 11, a reflector 12, and a rotating reflector 13. The laser light emitted by the laser output fiber 10 passes through the emission beam collimating lens 11 and the reflector 12 before reaching the 45° center-blocking reflective prism 1 of the laser scanning lens. After being reflected by the 45° center-blocking reflective prism 1, the laser light is incident on the surface of the target object. The laser scanning lens collects the reflected light from the target object and transmits it to the photodetector.

[0177] Figure 3 、 Figure 5 、 Figure 7 、 Figure 9 、 Figure 11 、 Figure 13 and Figure 15 The left side of the figure shows the optical path diagram of the photosensitive front end of the laser scanning lens of the present invention after the light with a wavelength of 1550nm passes through the object distance of 100m, 75m, 50m, 25m, 10m, 5m and 1m, respectively, indicating the process of the final focusing of the received light; Figure 4 、 Figure 6 、 Figure 8 、 Figure 10 、 Figure 12 、 Figure 14 and Figure 16 The circle in the right figure represents the photodetector's photosensitive surface, indicating the distribution of received light on that surface. Since the lens' entrance pupil is the object side of the aspheric lens 2, and the exit pupil is the detector's photosensitive surface, it can be seen that all energy entering the entrance pupil reaches the detector's photosensitive surface, resulting in good energy collection within an object distance range of 1-100m.

[0178] Figure 17 、 Figure 18 、 Figure 19 、 Figure 20 、 Figure 21 、 Figure 22 and Figure 23The following diagrams show the image plane illumination distribution of light with a wavelength of 1550nm passing through the laser scanning lens of the present invention at object distances of 100m, 75m, 50m, 25m, 10m, 5m, and 1m, respectively. The largest outer circle represents the photodetector's sensitive area, and the smaller central circle represents the obstruction area of the 45° centrally blocked reflective prism, representing the quantitative distribution of the received light's illumination. The light source in this embodiment is a circular Lambertian radiator with a radius of 5mm, the illumination of the light source is set to 1000 watts / square meter, and the image plane size is set to a circular detector with a diameter of 0.2mm. It can be seen that the lens has excellent light energy collection performance within the range of 1-100m, meeting the requirements of its application in 3D laser scanners.

[0179] The above examples are merely specific embodiments of the present invention. Obviously, the present invention is not limited to the above examples, and many variations are possible. All variations that can be directly derived or imagined by a person skilled in the art from the disclosure of the present invention should be considered to be within the scope of protection of the present invention.

Claims

1. A laser scanning lens with a large receiving range and high energy receiving efficiency, characterized in that: The laser scanning lens consists of a telescopic system and a focusing system. The entrance pupil of the lens and the exit pupil of the lens are conjugate. The light-receiving surface is located at the position of the entrance pupil of the lens, and the photosensitive surface of the photodetector is located at the position of the exit pupil of the lens. The telescopic system includes a first aspheric lens (2), an annular plane mirror (4), a spherical mirror (3), a 90° folding prism (5), and a spherical lens (6) that are sequentially arranged on the optical axis along the direction from the object side to the image side. The spherical mirror (3) is fixed on the image side surface of the first aspheric lens (2), and the annular plane mirror (4) is located between the image side surface of the first aspheric lens (2) and the object side surface of the 90° folding prism (5). An exit laser 45° central occlusion reflecting prism (1) is also fixed at the center of the object side surface of the first aspheric lens (2). The entrance pupil diameter D1 of the telescopic system and the exit pupil diameter D2 of the telescopic system satisfy: 100 < D1 / D2 < 1000 and D1 ≥ 35 mm. The front group focal length F1 of the telescopic system except the spherical lens (6) and the entrance pupil diameter D1 satisfy: 1 < F1 / D1 < 3. The focal length F2 of the spherical lens (6) in the telescopic system and the front group focal length F1 satisfy: 10 < F1 / F2 < 100.

2. The laser scanning lens with a large receiving range and high energy receiving efficiency according to claim 1, characterized in that: The exit pupil diameter D2 of the telescopic system is equal to the entrance pupil diameter of the focusing system, and the exit pupil diameter D3 of the focusing system is equal to the diameter of the photosensitive surface of the photodetector, and satisfy: 2 < D2 / D3 < 12.

3. The laser scanning lens with a large receiving range and high energy receiving efficiency according to claim 1, characterized in that: The diameter d0 of the 45° central occlusion reflecting prism (1) satisfies: d0 / D1 < 1 / 5.

4. The laser scanning lens with a large receiving range and high energy receiving efficiency according to claim 1, characterized in that: In the telescopic system, the light collected by the first aspheric lens (2) passes through the first aspheric lens (2) and first enters the outer ring reflecting surface of the annular plane mirror (4), then is reflected to the spherical mirror (3), and then passes through the inner ring of the annular plane mirror (4) and enters the 90° folding prism (5). After deflecting the optical path by 90°, it enters the spherical lens (6) and is focused to the focusing system.

5. The laser scanning lens with a large receiving range and high energy receiving efficiency according to claim 1, characterized in that: The focusing system includes a narrow-band filter (7) and a second aspheric lens (8) that are sequentially arranged on the optical axis along the direction from the object side to the image side. The air gaps between adjacent components satisfy: 0.05 ≤ d12 / D1 ≤ 2; 0.04 ≤ d23 / D1 ≤ 1.75; 0.05 ≤ d34 / D1 ≤ 2; 0.01 ≤ d45 / D1 ≤ 1; 0.01 ≤ d56 / D1 ≤ 1; 0.05 ≤ d67 / D1 ≤ 2; where, D1 is the entrance pupil diameter of the telescopic system, d12 is the air gap between the first aspheric lens (2) and the annular plane mirror (4), d23 is the air gap between the annular plane mirror (4) and the spherical mirror (3), d34 is the air gap between the spherical mirror (3) and the 90° folding prism (5), d45 is the air gap between the 90° folding prism (5) and the spherical lens (6), d56 is the air gap between the spherical lens (6) and the narrow-band filter (7), and d67 is the air gap between the narrow-band filter (7) and the second aspheric lens (8).

6. The laser scanning lens with a large receiving range and high energy receiving efficiency according to claim 5, characterized in that: Each component in the telescopic system satisfies the following relationships: 0.1 ≤ R1 / D1 ≤ 1, R2 = ∞, 0.5 ≤ R1 / t1 ≤ 3, 0.2 ≤ D1 / f1 ≤ 1.5; R3 = ∞, 0.2 ≤ d2out / t2 ≤ 15, 10 ≤ d2out / d2in ≤ 25; 0.2 ≤ R4 / d3 ≤ 5, 0.2 ≤ d3 / f2 ≤ 2, 1.5 ≤ d3 / t3 ≤ 12.5; R5 = ∞, R6 = ∞, 0.1 ≤ d4 / t4 ≤ 2, 0.1 ≤ d5 / t5 ≤ 2, 0.5 ≤ d4 / d5 ≤ 2; 0.1 ≤ R7 / R8 ≤ 10, 0.1 ≤ R7 / d6 ≤ 10, 0.1 ≤ R8 / d6 ≤ 10, 0.1 ≤ d6 / f3 ≤ 2; Where, R1, R2, t1 and f1 are respectively the object-side curvature radius, image-side curvature radius, thickness on the optical axis, and effective focal length of the first aspherical lens (2); R3, t2, d2out and d2in are respectively the reflection-side curvature radius, thickness on the optical axis, outer diameter, and inner diameter of the annular plane mirror (4); R4, d3, t3 and f2 are respectively the reflection-side curvature radius, entrance pupil diameter, thickness on the optical axis, and effective focal length of the spherical mirror (3); R5, R6, d4, d5, t4 and t5 are respectively the object-side curvature radius, image-side curvature radius, entrance pupil diameter, exit pupil diameter, thickness on the optical axis from the incident surface to the reflection surface, and thickness on the optical axis from the reflection surface to the exit surface of the 90° folding prism (5); R7, R8, d6 and f3 are respectively the object-side curvature radius, image-side curvature radius, entrance pupil diameter, thickness on the optical axis, and effective focal length of the spherical lens (6).

7. The laser scanning lens with a large receiving range and high energy receiving efficiency according to claim 6, characterized in that: The annular plane mirror (4) and the spherical mirror (3) satisfy the following relationship: 0.24 ≤ d2out / t2 ≤ 12, 10 ≤ d2out / d2in ≤ 22; 0.25 ≤ R4 / d3 ≤ 4.5, 0.25 ≤ d3 / f2 ≤ 1.8, 1.75 ≤ d3 / t3 ≤ 10.

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8. The laser scanning lens with a large receiving range and high energy receiving efficiency according to claim 5, characterized in that: Each element in the focusing system satisfies the following relationship: R9 = ∞, R10 = ∞, 1550 - 20 nm ≤ λ ≤ 1550 + 20 nm; 0.1 ≤ R11 / d6 ≤ 1, 0.1 ≤ R12 / d6 ≤ 1, 0.5 ≤ d6 / t6 ≤ 10, 0.2 ≤ d6 / f4 ≤ 10.5; Where, R9, R10 and λ are respectively the object-side curvature radius, image-side curvature radius, and wavelength of the narrowband filter; R11, R12, d6, t6 and f4 are respectively the object-side curvature radius, image-side curvature radius, entrance pupil diameter, thickness on the optical axis, and effective focal length f4 of the second aspherical lens (8).

9. The laser scanning lens with a large receiving range and high energy receiving efficiency according to claim 5, characterized in that: The narrowband filter (7) in the telescopic system and the focusing system is made of a glass material that satisfies the condition 12 < v1 / nd1 < 20, where v1 and ndl are respectively the d-line refractive index and Abbe number.

10. Application of the laser scanning lens according to any one of claims 1 to 9 in a laser 3D scanner, characterized in that: The laser emitted by the laser 3D scanner is reflected by the 45° central obstruction reflection prism (1) of the exit laser in the laser scanning lens and then incident on the surface of the target object, and the reflected light of the target object is collected by the laser scanning lens to the photodetector.

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