Optical configuration capable of effectively reducing angular resolution

Abstract

The utility model relates to an optical configuration capable of effectively reducing angular resolution, which comprises a first lens, a second lens, a third lens and a plane mirror which are coaxially arranged, and the lenses form a transmitting antenna of a laser range finder and are sequentially and coaxially arranged along the propagation direction of light beams output by a laser. The plane mirror is adjacent to the third lens, the two faces of the plane mirror are plated with thin films with the gradient transmittance of 1535 nm, edge stray light of laser can be eliminated, the diffraction effect is effectively reduced, the influence on the total length of an optical system is small, and the measurement precision is high. Compared with a conventional method for reducing the angular resolution by compressing the laser emission angle, the method is convenient to install and adjust, the tolerance of an optical system is large, and miniaturization and light weight of products can be achieved easily.

Description

Technical Field

[0001] The utility model relates to the technical field of laser optoelectronics, and particularly relates to an optical configuration capable of effectively reducing the angular resolution. Background Art

[0002] A laser rangefinder is an instrument that accurately measures the distance to a target by modulating a certain parameter of a laser. The transmitting antenna is used to collimate the laser beam emitted by the laser module and project it onto the target to be measured. The divergence angle is the angle at the corresponding point where the beam peak energy is 1 / e 2 , and the beam beyond 1 / e 2 also has a certain ranging ability to a certain extent. The core of improving the angular resolution of the transmitting antenna lies in controlling the beam diameter and energy size outside 1 / e 2 . In the existing optical configurations of laser rangefinders, when selecting a target, there is generally a problem that the angular resolution is much larger than the divergence angle.

[0003] For laser rangefinders, some products have certain requirements for angular resolution. Traditional optical configurations generally reduce the angular resolution by compressing the laser divergence angle. This method will increase the volume of the optical system to a certain extent, which is not conducive to the miniaturization and lightweight of the product. Summary of the Utility Model

[0004] Aiming at the defects of the prior art, the utility model provides an optical configuration capable of effectively reducing the angular resolution.

[0005] To achieve the above object, the technical solution adopted by the utility model is:

[0006] An optical configuration capable of effectively reducing the angular resolution, including a first lens, a second lens, a third lens and a plane mirror arranged coaxially. Each lens forms the transmitting antenna of the laser rangefinder and is arranged coaxially in sequence along the propagation direction of the laser beam output by the laser module, and is used to collimate and expand the laser beam emitted by the laser module and project it onto the target to be measured. The first lens is a double concave lens, the second lens is a plano-concave lens with a plane incident surface and a concave exit surface, the third lens is a plano-convex lens with a plane incident surface and a convex exit surface, and the plane mirror is arranged adjacent to the third lens, and both sides are coated with a gradient transmittance film of 1535 nm.

[0007] Further, the incident surfaces and the exit surfaces of the first lens, the second lens and the third lens are all coated with an antireflection film in the band of 1535 nm ± 5 nm.

[0008] Further, the material of the first lens is H-ZF7LA glass, the material of the second lens is H-QK3L, the material of the third lens is H-ZF7LA, and the material of the plane mirror is H-K9L glass.

[0009] Advantageous Effects:

[0010] The present utility model achieves the purpose of reducing angular resolution only by adding a customized plane mirror. Both sides of the plane mirror are coated with gradient transmittance films, which can eliminate the edge stray light of the laser and effectively reduce the diffraction effect. Taking the divergence angle of 0.7 mrad as an example, the present utility model can reduce the angular resolution of the system from 1.5 mrad to 0.8 mrad, and the total length of the optical system only increases by about 3 mm. Compared with the conventional method of reducing angular resolution by compressing the laser emission angle, it is convenient for alignment and adjustment, has a large tolerance for the optical system, and is conducive to the miniaturization and lightweight of the product. Description of the Drawings

[0011] Figure 1 Structural schematic diagram of the optical configuration of the present utility model;

[0012] Figure 2 Coating curve of the plane mirror.

[0013] Reference numerals: 1, first lens; 2, second lens; 3, third lens; 4, fourth plane mirror. Specific Embodiments

[0014] The following further describes the present utility model in detail with reference to the drawings and specific embodiments.

[0015] As Figure 1 shown, an optical configuration capable of effectively reducing angular resolution, which is used in a laser rangefinder, includes a first lens 1, a second lens 2, a third lens 3, and a plane mirror 4. Each device is arranged in sequence along the propagation direction of the laser beam output by the laser and their central axes coincide. The first lens 1, the second lens 2, the third lens 3, and the plane mirror 4 form the transmitting antenna of the laser rangefinder, collimating and expanding the laser beam emitted by the laser module and then projecting it onto the target to be measured. Among them, the first lens 1 is a double concave lens with both sides being concave surfaces, the second lens 2 is a plano-concave lens with the incident surface being a plane and the exit surface being a concave surface, and the third lens 3 is a plano-convex lens with the incident surface being a plane and the exit surface being a convex surface.

[0016] The plane mirror 4 is arranged adjacent to the third lens 3 and serves as an optical window. Both sides need to be coated with gradient transmittance films of 1535 nm. The coating curve is as Figure 2 shown, which can eliminate the edge stray light of the laser. At the same time, the setting of the plane mirror 4 effectively reduces the diffraction effect and can also improve the wear resistance, dust prevention, and fog prevention capabilities of the optical system.

[0017] Taking the optical configuration with a divergence angle of 0.7 mrad as an example, using this optical configuration, the angular resolution of the system can be reduced from 1.5 mrad to 0.8 mrad, and the stray light angle of this optical configuration can be reduced from 1.5 mrad to 0.8 mrad, effectively avoiding interference with other systems.

[0018] Both sides of the first lens 1, the second lens 2, and the third lens 3 need to be coated with an antireflection film in the wavelength band of 1535nm ± 5nm, which can increase the antenna transmittance.

[0019] The entrance pupil of this optical system is 0.7mm. Compared with the conventional methods of reducing angular resolution, it is convenient for alignment and has a larger tolerance for the optical system.

[0020] The specific parameters of the optical configuration are as follows:

[0021] The outer diameter of the first lens 1 is D = 3mm, the radius of curvature R1 = -4.5mm ± 0.5mm, the radius of curvature R2 = 4.5mm ± 0.5mm, the central thickness d = 2mm ± 0.1mm, and the material is H-ZF7LA.

[0022] The air gap between the first lens 1 and the second lens 2 is 8.5mm.

[0023] The outer diameter of the second lens 2 is D = 7mm, the radius of curvature R1 = ∞, the radius of curvature R2 = 10.6mm ± 0.5mm, the central thickness d = 2.2mm ± 0.1mm, and the material is H-QK3L.

[0024] The air gap between the second lens 2 and the third lens 3 is 5.9mm.

[0025] The outer diameter of the third lens 3 is D = 12mm, the radius of curvature R1 = ∞, the radius of curvature R2 = -19.558mm ± 0.5mm, the central thickness d = 3.2mm ± 0.1mm, and the material is H-ZF7LA.

[0026] The air gap between the third lens 3 and the plane mirror 4 is 0.2 - 1mm.

[0027] The outer diameter of the plane mirror 4 is D = 12mm, the radius of curvature R1 = ∞, the radius of curvature R2 = ∞, the central thickness d = 1mm ± 0.1mm, and the material is H-K9L.

[0028] Using the first lens 1, the second lens 2, the third lens 3, and the plane mirror 4 selected in the present invention to form a transmitting antenna, the laser beam emitted by the laser module is collimated and expanded and then projected onto the measured target, which can effectively reduce the angular resolution of the system. The entrance pupil of this optical configuration antenna is 0.7mm, the divergence angle ≤ 0.7mrad, the effective clear aperture Φ = 12mm, the beam expansion ratio ≥ 16 times. Innovatively, a customized plane mirror is added to the conventional optical antenna to eliminate the edge stray light of the laser. After adding the customized plane mirror, the angular resolution can be reduced from 1.5mrad to 0.8mrad, and the system length only increases by 3mm (the thickness of the plane mirror itself is about 1mm, and there is about 2mm of space reserved in front of the plane mirror and the lens). Compared with the traditional methods of reducing angular resolution, the effect is better.

[0029] The above are only the preferred embodiments of the present utility model, and do not impose any form of limitation on the present utility model. Although the present utility model has been disclosed above with the preferred embodiments, it is not intended to limit the present utility model. Any person skilled in the art can make some changes or modifications to equivalent embodiments by using the above-disclosed technical content within the scope of the technical solution of the present utility model. However, as long as it does not depart from the content of the technical solution of the present utility model, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present utility model still fall within the scope of the technical solution of the present utility model.

Claims

1. An optical configuration capable of effectively reducing angular resolution, characterized in that: The invention comprises a first lens, a second lens, a third lens and a plane mirror which are coaxially arranged, each lens constituting a transmitting antenna of a laser rangefinder, and being coaxially arranged in sequence along the propagation direction of the laser output light beam, and being used for collimating and expanding the laser light beam emitted by the laser module and projecting it onto a measured target, wherein the first lens is a biconcave lens, the second lens is a plano-concave lens, the incident surface is a plane, and the exit surface is a concave surface, the third lens is a plano-convex lens, the incident surface is a plane, and the exit surface is a convex surface, the plane mirror is arranged adjacent to the third lens, and both surfaces are coated with a 1535nm gradient transmittance film.

2. The optical configuration capable of effectively reducing angular resolution according to claim 1, characterized in that: The incident surface and the exit surface of the first lens, the second lens and the third lens all need to be coated with a 1535nm±5nm band anti-reflection film.

3. The optical configuration capable of effectively reducing angular resolution according to claim 1, characterized in that: The material of the first lens is H-ZF7LA glass, the material of the second lens is H-QK3L, the material of the third lens is H-ZF7LA, and the material of the plane mirror is H-K9L glass.

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