Laser scanning lens with large receiving range and high energy receiving efficiency and application thereof

Abstract

The invention provides a laser scanning lens with a large receiving range and high energy receiving efficiency and application thereof, and belongs to the field of optical lenses. A lens entrance pupil and a lens exit pupil are conjugated, a light receiving surface is located at the lens entrance pupil position, and a light sensing surface of a photoelectric detector is located at the lens exit pupil position; the entrance pupil diameter D1 and the exit pupil diameter D2 of the telescopic system meet the following conditions: 100lt; d1 / D2lt; 1000 and D is greater than or equal to 35 mm; the focal length F1 of the front group of the telescopic system and the entrance pupil diameter D1 satisfy 1lt; f1 / D1 < lt >; 3; the focal length F2 of the rear group and the focal length F1 of the front group of the telescopic system satisfy 10lt; f1 / F2lt; 100). According to the laser scanning lens, the entrance pupil and exit pupil conjugate design is adopted for the light-sensitive surface, 100% light receiving within the entrance pupil aperture non-blocking range can be achieved under the condition that receiving and transmitting are coaxial, the light energy receiving efficiency of the middle and long distance is greatly guaranteed, and the laser scanning lens has important application value in large-range high-precision laser three-dimensional scanning.

Description

Technical Field

[0001] The present invention relates to the field of optical lenses, and particularly to a laser scanning lens with a large reception range and high energy reception efficiency and its application. Background Art

[0002] As an efficient means for obtaining large-scale three-dimensional spatial point cloud data, large-scene high-precision laser three-dimensional scanning technology can achieve real, three-dimensional, and high-precision mapping from the physical space to the digital space, and has extensive applications in many important fields such as intelligent construction, smart city, digital mapping, and industrial inspection.

[0003] Large-scene high-precision laser three-dimensional scanning technology usually adopts the principle of laser ranging by the phase method or the pulse method. The laser is emitted from the transmitting optical system to the target object, and after diffuse reflection, it is collected by the receiving optical system and converted into an electrical signal by a photodetector, so as to perform signal processing and calculation, and finally obtain the ranging result of the target object.

[0004] Currently, the optical lenses in common laser three-dimensional scanning systems usually adopt the design and structure of object-image conjugation. Its advantage is that the design difficulty is low and it is easy to implement, but there is a problem that the image distance changes in real time with the object distance. Since the target object can randomly change from a short distance to a long distance, and the position of the photodetector is fixed after installation, it results in that the system can only ensure that the reflected light energy within a small range is received 100% within the entire measurement range, and only part of the energy can be received in other large ranges, causing a great waste of reflected light energy and having a very adverse impact on the measurement accuracy and measurement range of the system. Summary of the Invention

[0005] Aiming at the problem of low light collection efficiency of the optical lenses in common laser three-dimensional scanning systems, the present invention proposes a laser scanning lens with a large reception range and high energy reception efficiency and its application. The laser scanning lens adopts the design structure of entrance pupil and exit pupil conjugation, improves the energy reception efficiency, and can achieve large-range and high-precision laser three-dimensional scanning.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] In the first aspect, the present invention provides a laser scanning lens with a large reception range and high energy reception efficiency, which is characterized in that the laser scanning lens 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 collection 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;

[0008] The telescopic system described above includes a first aspherical lens, an annular planar mirror, a spherical mirror, a 90° folding prism, and a spherical lens, which 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° folding 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 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 (excluding the spherical lens) and the entrance pupil diameter D1 of the telescopic system 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 satisfies: 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 passes through the first aspherical lens and then is incident on the outer ring reflecting surface of the annular planar mirror, then reflected to the spherical mirror, and then passes through the inner ring of the annular planar mirror and is incident on the 90° folding 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, which 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 telescopic system, d12 is the air gap between the first aspherical lens and the annular planar mirror, d23 is the air gap between the annular planar mirror and the spherical mirror, d34 is the air gap between the spherical mirror 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 aspherical lens.

[0021] As a preference of the present invention, each element in the telescopic system satisfies the following relationships:

[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 aspherical lens; 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 planar mirror; 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; 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; 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.

[0028] As a preference of the present invention, the annular planar mirror and the spherical mirror satisfy the following relationships:

[0029] 0.24 ≤ d2 / 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] As a preference of 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 spectral transmittance 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 aspheric lens.

[0035] As a preference of the present invention, the narrow - band filter 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 nd1 are respectively the d - line refractive index and Abbe number.

[0036] As a preference of the present invention, the laser emitted by the laser 3D scanner is reflected by the 45° central - occlusion 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 relationships 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 entrance - pupil and exit - pupil conjugation, 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 common object - image conjugate optical lenses, 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] A brief introduction to the accompanying drawings of the embodiments of the invention is given below. Referring to and reading them will provide a clearer understanding of the advantages and overall structure of the present invention, and those skilled in the art can also obtain other characteristic parameters related to the present invention based on the drawings.

[0040] Figure 1 It is the overall optical path diagram of a laser scanning lens with a large reception range and high energy reception efficiency shown by the present invention.

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

[0042] Figure 3 It 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 100 m.

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

[0044] Figure 5 It 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 75 m.

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

[0046] Figure 7 It 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 50 m.

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

[0048] Figure 9 It 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 25 m.

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

[0050] Figure 11 It 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 10 m.

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

[0052] Figure 13 It 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 5 m.

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

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

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

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

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

[0058] Figure 19 It is the image plane illuminance distribution diagram of the laser scanning lens with an object distance of 50 m under a given light source and with occlusion.

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

[0060] Figure 21 It is the image plane illuminance distribution diagram of the laser scanning lens with an object distance of 10 m under a given light source and with occlusion.

[0061] Figure 22 It is the image plane illuminance distribution diagram of the laser scanning lens with an object distance of 5 m under a given light source and with occlusion.

[0062] Figure 23 It is the image plane illuminance distribution diagram of the laser scanning lens with an object distance of 1 m under a given light source and with occlusion. Detailed implementation manners

[0063] To better illustrate the advantages and characteristics of the present invention, the present invention will be specifically described below with reference to the accompanying drawings. The described embodiments are only one embodiment of the present invention, and all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

[0064] Refer to the attached Figure 1, the present invention provides a laser scanning lens with a large receiving range and high energy receiving efficiency. This 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 sequentially 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 narrowband 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 is incident on the outer ring reflecting surface of the annular plane mirror 4, and then is reflected to the spherical mirror 3, and then passes through the inner ring of the annular plane mirror 4 and is incident on 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 obstruction, so a 45° central obstruction reflection 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 obstruction reflection prism 1 satisfies: d0 / D1 < 1 / 5, so as to ensure that the energy loss due to central obstruction 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 its second surface is a plane; the spherical lens 6 and the second aspherical lens 8 are both double-convex positive lenses, and both the front and rear surfaces are aspherical surfaces.

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

[0068] The object side curvature radius R1, the image side curvature radius R2, the entrance pupil diameter D1, the thickness t1 on the optical axis, and the 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 satisfied:

[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 radius of curvature R3 of the reflecting surface, the outer diameter d2out, the inner diameter d2in, and the thickness t2 on the optical axis of the annular plane mirror 4 satisfy:

[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 satisfied:

[0083] R3 = ∞;

[0084] 0.24 ≤ d2out / t2 ≤ 12;

[0085] 10 ≤ d2out / d2in ≤ 22.

[0086] The radius of curvature 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 mirror 3 satisfy:

[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 satisfied:

[0091] 0.25 ≤ R4 / d3 ≤ 4.5;

[0092] 0.25 ≤ d3 / f2 ≤ 1.8;

[0093] 1.75 ≤ d3 / t3 ≤ 10.5.

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

[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 satisfied:

[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, the image-side curvature radius R8, the thickness t6 on the optical axis, and the 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 satisfied:

[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, the image-side curvature radius R10, and the spectral transmittance range λ of the narrowband filter 7 satisfy the following conditions:

[0117] R9 = ∞;

[0118] R10 = ∞;

[0119] 1550 - 20 nm ≤ λ ≤ 1550 + 20 nm.

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

[0121] R9 = ∞;

[0122] R10 = ∞;

[0123] 1550 - 15 nm ≤ λ ≤ 1550 + 15 nm.

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

[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 satisfied:

[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] Among the above - mentioned components, that is, the aspherical lens 2, the spherical mirror 3, the annular planar mirror 4, the 90° turning prism 5, the spherical lens 6, the narrow - band filter 7, and the second aspherical lens 8, the air gaps between adjacent components satisfy the following:

[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 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.

[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 to receiving energy so as to increase the measurement distance. When the three-dimensional scanner is working, the target distance may mutate in a very short time. Therefore, the optical system is a system without moving parts. So, when the target changes from near (1 - 100 m) with the detector position unchanged in the pupil-to-pupil imaging mode, the light energy entering the aperture of the optical system will be received by the detector.

[0149] In this embodiment, except that the second aspheric lens is made of a 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 to the collection of light rays of a specific wavelength by the system, and using a unified material is beneficial to improving the feasibility and industrialization of the system.

[0150] The laser scanning lens of the present invention will be described below with examples. The units of its focal length, axial distance, radius of curvature, and axial thickness are mm. The design data of the laser scanning lens are shown in Table 1 and Table 2, which list the object-side radius of curvature and image-side radius of curvature R of each lens and mirror of the laser scanning lens, the axial thickness of each lens, the distance d between two adjacent lenses, and the refractive index nd and Abbe number vd of the lens glass material. It should be noted that in this embodiment, the units of R and d are both millimeters (mm).

[0151] Table 1

[0152] Among them, the meanings of each symbol are as follows.

[0153] R: The radius of curvature of each surface in the lens;

[0154] S1~S14: Each surface of the lens element;

[0155] S0: The surface of the target object;

[0156] S1: The object side of the first aspherical lens;

[0157] S2: The image side of the first aspherical lens;

[0158] S3: The annular plane reflecting surface;

[0159] S4: The spherical reflecting surface;

[0160] S5: The incident surface of the 90° folding prism;

[0161] S6: The exit surface of the 90° folding prism;

[0162] S7: The object side of the spherical lens;

[0163] S8: The image side of the spherical lens;

[0164] S9: The front surface of the narrowband filter;

[0165] S10: The rear surface of the narrowband filter;

[0166] S11: The object side of the second aspherical lens;

[0167] S12: The image side of the second aspherical lens;

[0168] S13: The object side of the detector glass cover plate;

[0169] S14: The image side of the detector glass cover plate;

[0170] S1*, S11*, S12* are aspherical surfaces, and the aspherical surface expression is:

[0171]

[0172] The corresponding aspheric coefficients are shown in Table 2 below:

[0173] Table 2

[0174] Figure 2 The following is a schematic structural diagram of applying the laser scanning lens of the present invention in a laser three-dimensional scanner. The figure includes the laser scanning lens of the present invention, a photosensitive detector 9, a laser output optical fiber 10, a transmitting beam collimating lens 11, a reflecting mirror 12, and a rotating reflecting mirror 13. The laser emitted from the laser output optical fiber 10 passes through the transmitting beam collimating lens 11 and the reflecting mirror 12 in sequence and then reaches the 45° central blocking reflecting prism 1 of the laser scanning lens. After being reflected by the outgoing laser 45° central blocking reflecting prism 1, it is incident on the surface of the target object, and the reflected light of the target object is collected by the laser scanning lens and sent to the photodetector.

[0175] Figure 3 , Figure 5 , Figure 7 , Figure 9 , Figure 11 , Figure 13 and Figure 15 The left diagrams of respectively show the front optical path diagrams of the photosensitive surface after the light with a wavelength of 1550 nm passes through the laser scanning lens of the present invention at object distances of 100 m, 75 m, 50 m, 25 m, 10 m, 5 m, and 1 m, 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 In the right diagrams of , the circle represents the photosensitive surface of the photodetector, indicating the distribution of the received light on the photosensitive surface. Since the entrance pupil of the lens is the object side of the aspheric lens 2 and the exit pupil is the photosensitive surface of the detector, it can be seen that the energy entering the entrance pupil can all reach the photosensitive surface of the detector. Therefore, a good energy collection effect can be achieved within the range of object distances from 1 m to 100 m.

[0176] Figure 17 , Figure 18 , Figure 19 , Figure 20 , Figure 21 , Figure 22 and Figure 23The image plane illumination distribution diagrams of light with a wavelength of 1550nm after passing through the laser scanning lens of the present invention at object distances of 100m, 75m, 50m, 25m, 10m, 5m, and 1m are respectively shown. The largest outer circle is the photosensitive area of ​​the photodetector, and the central small circle is the blocking area of ​​the 45° central blocking reflection prism, indicating the quantitative distribution of the illumination of the received light. The light source set in this embodiment is a circular Lambertian radiator with a radius of 5mm, the set light source radiation illumination is 1000 watts / square meter, and the set image plane size is a circular detector with a diameter of 0.2mm. It can be seen that the lens has good light energy collection performance in the range of 1-100m, which can meet the needs of its application in three-dimensional laser scanners.

[0177] The above examples are only 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 associated with the contents disclosed by a person skilled in the art should be considered as the protection scope of the present invention.

Claims

1. A laser scanning lens with a large reception range and high energy reception efficiency, characterized in that, The laser scanning lens is composed of a telescopic system and a focusing system. The entrance pupil and 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) arranged in sequence on the optical axis along 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 outgoing 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 and exit pupil diameter D2 of the telescopic system satisfy: 100 < D1 / D2 < 1000 and D1 ≥ 35 mm. The front group focal length F1 and entrance pupil diameter D1 of the telescopic system except the spherical lens (6) satisfy: 1 < F1 / D1 < 3. The focal length F2 of the spherical lens (6) and the front group focal length F1 in the telescopic system satisfy: 10 < F1 / F2 < 100.

2. The laser scanning lens with a large reception range and high energy reception efficiency according to claim 1, wherein 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 satisfies: 2 < D2 / D3 < 12.

3. The laser scanning lens with a large reception range and high energy reception 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 reception range and high energy reception efficiency according to claim 1, wherein The focusing system includes a narrow-band filter (7) and a second aspheric lens (8) arranged in sequence on the optical axis along the object side to the image side. The air gap between adjacent elements satisfies: 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 reception range and high energy reception efficiency according to claim 5, characterized in that Each element 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; Wherein, 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 - surface 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 - surface 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 relationships: 0.24 ≤ d2 / t2 ≤ 12, 10 ≤ d2out / d2in ≤ 22; 0.25 ≤ R4 / d3 ≤ 4.5, 0.25 ≤ d3 / f2 ≤ 1.8, 1.75 ≤ d3 / t3 ≤ 10.

5.

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 relationships: 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; Wherein, R9, R10 and λ are respectively the object - side curvature radius, image - side curvature radius and spectral transmittance 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 (8).

9. The laser scanning lens with a large reception range and high energy reception efficiency according to claim 5, characterized in that The narrow - band 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 nd1 are respectively the d - line refractive index and Abbe number.

10. Application of the laser scanning lens with a large reception range and high energy reception efficiency according to any one of claims 1-9 in a laser three-dimensional scanner, characterized in that, The laser emitted by the laser 3D scanner is reflected by the 45° central - blocked reflection prism (1) 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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