Large-aperture high-precision laser beam expanding and collimating system

Abstract

The utility model relates to a laser beam expanding and collimating system, and provides a large-aperture high-precision laser beam expanding and collimating system in order to solve the problems that an existing large-aperture beam expanding system is low in wavefront precision, high in manufacturing cost and the like. The optical system comprises a first lens with negative focal power, a second lens with positive focal power, a third lens with negative focal power and a fourth lens with positive focal power which are sequentially arranged along the propagation direction of incident light, the first lens is a biconcave lens and is used for receiving incident light and primarily diverging the incident light; the second lens is a front-concave rear-convex lens and is used for correcting the divergence angle of emergent light of the first lens; the third lens is a biconcave lens and is used for expanding the beam diameter of emergent light of the second lens and improving the beam quality; the fourth lens is a biconvex lens and is used for shaping and optimizing emergent light of the third lens; the object side surfaces and the image side surfaces of the first lens, the second lens, the third lens and the fourth lens are spherical surfaces.

Description

Technical Field

[0001] The utility model relates to a laser beam expansion and collimation system, in particular to a large-caliber and high-precision laser beam expansion and collimation system. Background Art

[0002] With the rapid development of laser technology, people's high standards for laser system performance have become an industry consensus. In key areas such as automatic transceiver matching of laser radar, high-power laser emitting devices, laser ranging and optical communications, it is particularly urgent to develop laser beam expansion and collimation systems with excellent performance. These systems greatly improve the collimation performance of the beam by adjusting the laser beam, expanding the beam diameter and compressing the spatial divergence angle. The carefully optimized large-aperture laser beam expansion and collimation system is not only the core to ensure the efficient operation of the laser transmission system, but also an indispensable core component of laser radar and other high-end laser instruments and equipment.

[0003] The existing large-aperture beam expansion system has a low wavefront accuracy of only about λ / 4; and most of them use aspheric lenses, which have high manufacturing costs and complex processing; it is difficult to simultaneously meet the requirements of large aperture and high precision for laser beam expansion and collimation systems in the field of precision measurement and control. Utility Model Content

[0004] The purpose of the utility model is to solve the problems of low wavefront accuracy, high manufacturing cost, complex processing and difficulty in simultaneously meeting large aperture and high precision in existing large-aperture beam expansion systems, and to provide a large-aperture high-precision laser beam expansion and collimation system.

[0005] To achieve the above purpose, the technical solution provided by the utility model is:

[0006] A large-aperture, high-precision laser beam expansion and collimation system, which is special in that:

[0007] It comprises a first lens with negative optical focal power, a second lens with positive optical focal power, a third lens with negative optical focal power, and a fourth lens with positive optical focal power, which are sequentially arranged along the propagation direction of the incident light;

[0008] The object side of the first lens, the second lens, the third lens and the fourth lens are defined as the front and the image side is the rear; the first lens is a biconcave lens, used for receiving incident light and preliminarily diverging the incident light; the second lens is a front convex and rear concave lens, used for correcting the divergence angle of the light emitted from the first lens; the third lens is a biconcave lens, used for expanding the beam diameter of the light emitted from the second lens and improving the beam quality; the fourth lens is a biconvex lens, used for shaping and optimizing the light emitted from the third lens to achieve the final required beam diameter; the object side surface and image side surface of the first lens, the second lens, the third lens and the fourth lens are all spherical surfaces.

[0009] Furthermore, the curvature radius R1o of the beam incident surface of the first lens satisfies: -27.5mm≤R1o≤-25.5mm, and the curvature radius R1i of the beam exit surface satisfies: 44.5mm≤R1i≤46.5mm; the curvature radius R2o of the beam incident surface of the second lens satisfies: -145.5mm≤R2o≤-143.7mm, and the curvature radius R2i of the beam exit surface satisfies: -34.5mm≤R2i≤-32 .5mm; the curvature radius R3o of the light beam incident surface of the third lens satisfies: -357mm≤R3o≤-355mm, and the curvature radius R3i of the light beam exit surface satisfies: 62.5mm≤R3i≤64.5mm; the curvature radius R4o of the light beam incident surface of the fourth lens satisfies: 775.2mm≤R4o≤777.2mm, and the curvature radius R4i of the light beam exit surface satisfies: -105.5mm≤R4i≤-104.5mm.

[0010] Furthermore, the first lens and the second lens are both made of optical glass H-ZPK5; the third lens and the fourth lens are both made of optical glass H-FK61B.

[0011] Furthermore, the thickness of the first lens is 1.5 mm to 3.0 mm; the thickness of the second lens is 8.25 mm to 9.25 mm; the thickness of the third lens is 2.5 mm to 4.5 mm; and the thickness of the fourth lens is 15 mm to 17 mm.

[0012] Furthermore, the optical distance between the first lens and the second lens is 26 mm to 28 mm; the optical distance between the second lens and the third lens is 0.8 mm to 1.3 mm; and the optical distance between the third lens and the fourth lens is 86 mm to 88 mm.

[0013] Furthermore, the distance between the object-side surface of the first lens and the image-side surface of the fourth lens is 144 mm to 150 mm.

[0014] Furthermore, the object side surface and image side surface of the first lens, the second lens, the third lens and the fourth lens are coated with a high anti-reflection film.

[0015] Furthermore, the single-side transmittance of each high antireflection film is 0.995.

[0016] Compared with the prior art, the beneficial effects of the utility model are:

[0017] 1. The large-aperture, high-precision laser beam expansion and collimation system provided by the utility model is a non-real focus optical system in which both the incident light and the outgoing light are parallel light. It can be stably applied to high-power laser systems. As a large-aperture optical beam expansion system in full-duplex mode, it is particularly suitable for use in the automatic transceiver system of laser radar.

[0018] 2. The large-aperture, high-precision laser beam expansion and collimation system provided by the utility model has a beam expansion component that can ensure imaging quality while maintaining a high beam expansion multiple; it has a simple structure, is easy to integrate, and is cost-effective.

[0019] 3. The large-aperture, high-precision laser beam expansion and collimation system provided by the utility model has a five-fold beam expansion ratio when the maximum incident parallel light aperture is Φ18mm, the field of view angle is ±0.25°, and the maximum exit parallel light aperture is Φ90mm; when the residual wave aberration RMS is designed to be 0.0154λ (central field of view), the system accuracy after processing and assembly reaches 0.035λ, which can achieve high-quality transmission of the laser beam.

[0020] 4. The large-aperture, high-precision laser beam expansion and collimation system provided by the utility model has a distance of 145.962 mm between the beam incident surface of the first lens and the beam exit surface of the fourth lens. Its compact structural design facilitates integration into various laser systems to meet application requirements with space and weight limitations.

[0021] 5. The large-aperture, high-precision laser beam expansion and collimation system provided by the utility model has no real focus. Under high-power air medium conditions, when a high-energy laser beam passes through the collimation system, it can effectively avoid air breakdown or heating caused by the real focus generated by convergence, thereby causing the phenomenon of beam quality degradation.

[0022] 6. The large-aperture, high-precision laser beam expansion and collimation system provided by the utility model has no center obstruction, reduces obstacles in the beam path, and avoids diffraction effects and energy losses.

[0023] 7. The large-aperture, high-precision laser beam expansion and collimation system provided by the utility model has each lens which is a spherical lens, has low processing difficulty and loose tolerance; it is easy to assemble and adjust, has low cost, has strong engineering feasibility, and is easy to mass produce.

[0024] 8. The large-aperture, high-precision laser beam expansion and collimation system provided by the utility model has a full-duplex mode, allowing simultaneous transmission and reception operations, which significantly improves the communication capability and efficiency of the system and is suitable for application scenarios requiring high-speed data transmission and high-precision synchronization. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the structure of an embodiment of the utility model;

[0026] Figure 2 This is the wavefront diagram of the image plane of the embodiment of the utility model under a 0 degree field of view;

[0027] Figure 3 This is the wavefront diagram of the image plane of the embodiment of the utility model under a 0.1 degree field of view;

[0028] Figure 4 This is the wavefront diagram of the image plane of the embodiment of the utility model under a 0.25 degree field of view;

[0029] Figure 5 A system point diagram of an embodiment of the utility model;

[0030] Figure 6 This is the actual detection wavefront diagram after the installation and adjustment of the embodiment of the utility model is completed;

[0031] Description of reference numerals:

[0032] L1-first lens, L2-second lens, L3-third lens, L4-fourth lens. DETAILED DESCRIPTION

[0033] The utility model is further described below in conjunction with the accompanying drawings and specific embodiments.

[0034] See also Figure 1 A large-aperture high-precision laser beam expansion and collimation system comprises a first lens L1 with negative focal power, a second lens L2 with positive focal power, a third lens L3 with negative focal power, and a fourth lens L4 with positive focal power, which are sequentially arranged along the propagation direction of the incident light; the object side of the first lens L1, the second lens L2, the third lens L3 and the fourth lens L4 are defined as the front side and the image side as the rear side; the first lens L1 is a biconcave lens, which is used to receive the incident light and initially diverge the incident light; the second lens L2 is a front convex and rear concave lens, which is used to correct the divergence angle of the light emitted from the first lens L1; the third lens L3 is a biconcave lens, which is used to expand the beam diameter of the light emitted from the second lens L2 and improve the beam quality; the fourth lens L4 is a biconvex lens, which is used to shape and optimize the light emitted from the third lens L3 to achieve the final required beam diameter; the object side surface and image side surface of the first lens L1, the second lens L2, the third lens L3 and the fourth lens L4 are all spherical surfaces.

[0035] The detailed parameters of the first lens L1, the second lens L2, the third lens L3 and the fourth lens L4 are described below:

[0036] Radius of curvature:

[0037] The object side curvature radius R1o of the first lens satisfies: R1o=-26.2mm, and the image side curvature radius R1i satisfies: R1i=45.59mm; the object side curvature radius R2o of the second lens satisfies: R2o=-144.7mm, and the image side curvature radius R2i satisfies: R2i=-33.27mm; the object side curvature radius R3o of the third lens satisfies: R3o=-356.5mm, and the image side curvature radius R3i satisfies: R3i=63.68mm; the object side curvature radius R4o of the fourth lens satisfies: R4o=776.2mm, and the image side curvature radius R4i satisfies: R4i=-105.11mm.

[0038] Material:

[0039] The first lens L1 and the second lens L2 are both made of optical glass H-ZPK5; the third lens L3 and the fourth lens L4 are both made of optical glass H-FK61B.

[0040] thickness:

[0041] The thickness of the first lens L1 is 2.3 mm;

[0042] The thickness of the second lens L2 is 9.08 mm;

[0043] The thickness of the third lens L3 is 3.5 mm;

[0044] The thickness of the fourth lens L4 is 16.34 mm.

[0045] Optical spacing:

[0046] The optical distance between the first lens L1 and the second lens L2 is 26.113 mm;

[0047] The optical distance between the second lens L2 and the third lens L3 is 1 mm;

[0048] The optical distance between the third lens L3 and the fourth lens L4 is 87.629 mm

[0049] The distance between the object-side surface of the first lens L1 and the image-side surface of the fourth lens L4 is 145.962 mm.

[0050] This embodiment uses a total of four spherical lenses, and the object side and image side of each lens are coated with a high anti-reflection film, and the single-side transmittance of each high anti-reflection film is 0.995; the transmittance of the material H-ZPK5 is 0.996; the transmittance of the material H-FK61B is 0.996; the total transmittance of the lens group is 0.953.

[0051] Below Figure 2 to Figure 6 To explain:

[0052] Figures 2 to 4 is the image wavefront diagram of this embodiment under different fields of view, Figure 2 This is the image wavefront diagram under 0 degree field of view, the RMS value reaches 0.0154λ. Figure 3 This is the image wavefront diagram under 0.1 degree field of view. Figure 4 This is the wavefront diagram of the image plane under a 0.25 degree field of view; Figure 5 : is the system spot diagram corresponding to the present embodiment under three different fields of view, and the radius of the Airy disk is 3.62 μm; Figure 6 This is the actual detection wavefront diagram of the system after the adjustment of this embodiment is completed, and the RMS is better than λ / 20. It can be seen that this embodiment, as a large-aperture optical beam expansion system in full-duplex mode, can be stably applied to actual scenarios such as high-power laser systems, and is particularly suitable for automatic transceiver systems of laser radars; the beam expansion component in this system can ensure imaging quality while maintaining a high beam expansion multiple; in addition, the system has a simple structure, is easy to integrate, and is cost-effective.

Claims

1. A large-aperture, high-precision laser beam expansion and collimation system, characterized by: It comprises a first lens (L1) with negative focal power, a second lens (L2) with positive focal power, a third lens (L3) with negative focal power, and a fourth lens (L4) with positive focal power, which are sequentially arranged along the propagation direction of the incident light; The invention defines that the incident direction of the light beam of the first lens (L1), the second lens (L2), the third lens (L3) and the fourth lens (L4) is forward, and the light beam exit direction is backward; the first lens (L1) is a biconcave lens, used for receiving the incident light and preliminarily diverging the incident light; the second lens (L2) is a front concave and rear convex lens, used for correcting the divergence angle of the light emitted from the first lens (L1); the third lens (L3) is a biconcave lens, used for expanding the light beam diameter of the light emitted from the second lens (L2) and improving the light beam quality; the fourth lens (L4) is a biconvex lens, used for shaping and optimizing the light emitted from the third lens (L3) to achieve the final required light beam diameter; the light beam incident surface and light beam exit surface of the first lens (L1), the second lens (L2), the third lens (L3) and the fourth lens (L4) are all spherical surfaces.

2. A large-aperture, high-precision laser beam expansion and collimation system according to claim 1, characterized in that: The curvature radius R1o of the light beam incident surface of the first lens (L1) satisfies: -27.5mm≤R1o≤-25.5mm, and the curvature radius R1i of the light beam exit surface satisfies: 44.5mm≤R1i≤46.5mm; The curvature radius R2o of the beam incident surface of the second lens (L2) satisfies: -145.5mm≤R2o≤-143.7mm, and the curvature radius R2i of the beam exit surface satisfies: -34.5mm≤R2i≤-32.5mm; The curvature radius R3o of the light beam incident surface of the third lens (L3) satisfies: -357mm≤R3o≤-355mm, and the curvature radius R3i of the light beam exit surface satisfies: 62.5mm≤R3i≤64.5mm; The curvature radius R4o of the light beam incident surface of the fourth lens (L4) satisfies: 775.2mm≤R4o≤777.2mm, and the curvature radius R4i of the light beam exit surface satisfies: -105.5mm≤R4i≤-104.5mm.

3. A large-aperture, high-precision laser beam expansion and collimation system according to claim 2, characterized in that: The first lens (L1) and the second lens (L2) are both made of optical glass H-ZPK5; the third lens (L3) and the fourth lens (L4) are both made of optical glass H-FK61B.

4. A large-aperture high-precision laser beam expansion and collimation system according to claim 3, characterized in that: The thickness of the first lens (L1) is 1.5 mm to 3.0 mm; The thickness of the second lens (L2) is 8.25 mm to 9.25 mm; The thickness of the third lens (L3) is 2.5 mm to 4.5 mm; The thickness of the fourth lens (L4) is 15 mm to 17 mm.

5. A large-aperture high-precision laser beam expansion and collimation system according to claim 4, characterized in that: The optical distance between the first lens (L1) and the second lens (L2) is 26 mm to 29 mm; The optical distance between the second lens (L2) and the third lens (L3) is 0.8 mm to 1.3 mm; The optical distance between the third lens (L3) and the fourth lens (L4) is 85 mm to 88 mm.

6. A large-aperture, high-precision laser beam expansion and collimation system according to claim 5, characterized in that: The distance between the light beam incident surface of the first lens (L1) and the light beam exit surface of the fourth lens (L4) is 144 mm to 150 mm.

7. A large-aperture, high-precision laser beam expansion and collimation system according to claim 6, characterized in that: The light beam incident surfaces and light beam exit surfaces of the first lens (L1), the second lens (L2), the third lens (L3) and the fourth lens (L4) are all coated with high anti-reflection films.

8. The large-aperture, high-precision laser beam expansion and collimation system according to claim 7, characterized in that: The single-side transmittance of each high antireflection film is 0.995.

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