A dual-band continuously zooming beam expander lens

Abstract

The present invention relates to a dual-band continuous zoom beam expander lens, comprising: a lens body; the lens body comprises: a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens, arranged coaxially from front to back along the optical axis from the object side to the image side; the first lens is a front fixed lens group that remains stationary during zooming; the second and third lenses are a zoom lens group; the fourth lens is a compensating lens group; the fifth and sixth lenses are a rear fixed lens group; the zoom lens group and the compensating lens group can be moved forward and backward along the optical axis, respectively, so that the output laser beam expansion magnification of the lens body can be adjusted. The present invention can achieve 1.064μm and medium-wave 3.8μm dual-band co-aperture continuous zoom beam expander, involving a large band span, which can meet both the distance measurement of 1.064μm laser and the infrared auxiliary illumination of 3.8μm medium-wave laser. The co-aperture design of the two bands can effectively reduce the volume and weight.

Description

Technical Field

[0001] The present invention relates to the technical field of laser beam expansion, and in particular to a dual-band continuously variable magnification beam expansion lens. Background Art

[0002] Laser beam expansion systems are widely used in laser ranging, laser irradiation, laser lighting, and other fields. By expanding the diameter of the laser output beam, the beam divergence angle of the output light can be effectively reduced, thereby controlling the spot size of the laser irradiated to a distant target scene, ensuring irradiation accuracy and improving received power. The optimal laser wavelength or beam expansion ratio for different application scenarios is likely to be different, so the beam expansion lens needs to have a continuous zoom function. 1.064μm wavelength laser is mainly used for laser ranging, and 3.8μm medium-wave laser is used for infrared lighting due to its strong medium-wave infrared radiation energy. In order to achieve system compactness and miniaturization, both need to have a common aperture and continuous zoom beam expansion function.

[0003] The domestic patent "A Laser Collimation Optical System 201310626156.6" achieves beam expansion at two wavelengths, 1.064 and 1.57, but lacks continuous zoom capability, and its wavelength does not cover the medium-wavelength 3.8μm. The patent "A Miniaturized Ultraviolet Laser Variable-Magnification Beam Expander 202011207819.7" achieves continuous-magnification laser beam expansion, but is designed for ultraviolet wavelengths and has a single wavelength. The patent "A Dual-Wavelength, High-Magnification, Continuously Variable-Magnification Laser Beam Expander CN 113204122A" achieves continuous-magnification beam expansion for two wavelengths, but both wavelengths are in the visible band and lack medium-wavelength beam expansion. Summary of the Invention

[0004] The present invention aims to solve the technical problems in the prior art and provides a dual-band continuously variable magnification beam expander lens.

[0005] In order to solve the above technical problems, the technical solutions of the present invention are as follows:

[0006] A dual-band continuously zooming and beam expanding lens, comprising: a lens body; the lens body comprising: a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens, which are coaxially arranged in sequence from front to back along an optical axis from the object side to the image side;

[0007] The first lens is a meniscus positive lens, with the concave surface of the first lens facing the incident direction of the laser. The first lens includes two surfaces, S1 and S2, wherein the curvature radius of the S1 surface is R1 = -100.03 mm; the curvature radius of the S2 surface is R2 = -80.89 mm; and the center thickness d1 between the two surfaces on the optical axis is 6 mm.

[0008] The second lens is a biconcave negative lens; the second lens includes two surfaces, S3 and S4, wherein the curvature radius of the S3 surface is R3 = -23.55 mm; the curvature radius of the S4 surface is R4 = 173.55 mm; and the center thickness d2 between the two surfaces on the optical axis is 5 mm;

[0009] The third lens is a biconcave negative lens; the third lens includes two surfaces, S5 and S6, wherein the curvature radius of the S5 surface is R5 = -70 mm; the curvature radius of the S6 surface is R6 = 127.5 mm; and the center thickness d3 between the two surfaces on the optical axis is 5 mm;

[0010] The fourth lens is a biconvex positive lens; the fourth lens includes two surfaces, S7 and S8, wherein the curvature radius of the S7 surface is R7 = 253.4 mm; the curvature radius of the S8 surface is R8 = -244 mm; the center thickness d4 between the two surfaces on the optical axis is 8 mm;

[0011] The fifth lens is a plano-concave negative lens, with the concave surface of the fifth lens facing the incident direction of the laser. The fifth lens includes two surfaces, S9 and S10, wherein the curvature radius of the S9 surface is R9 = -79.5 mm; the curvature radius of the S10 surface is R10 = ∞; and the center thickness d5 between the two surfaces on the optical axis is 11 mm.

[0012] The sixth lens is a meniscus convex positive lens, and the concave surface of the sixth lens faces the incident direction of the laser; the sixth lens includes two surfaces S11 and S12, wherein the curvature radius R11 of the S11 surface is

[0013] -707.8mm; radius of curvature R12 of the S12 surface = -148.3mm; center thickness d6 between the two surfaces on the optical axis = 17mm;

[0014] The first lens is a front fixed lens group, which remains stationary during zooming and has a positive focal length f1;

[0015] The second lens and the third lens form a zoom lens group, and the focal length f2 is negative;

[0016] The fourth lens is a compensation lens group, and the focal length f3 is positive;

[0017] The fifth lens and the sixth lens form a rear fixed lens group, and the focal length f4 is positive;

[0018] The zoom lens group and the compensation lens group can be moved forward and backward along the optical axis respectively, so that the beam expansion magnification of the output laser of the lens body can be adjusted.

[0019] In the above technical solution, the interval between the first lens and the second lens is 14-170.8 mm; the interval between the second lens and the third lens is 8 mm; the interval between the third lens and the fourth lens is 6.83-18.98 mm; the interval between the fourth lens and the fifth lens is 64.2-233.2 mm; and the interval between the fifth lens and the sixth lens is 5 mm.

[0020] In the above technical solution, the d-light refractive indices of the first to sixth lenses are Nd1-Nd6, respectively, satisfying:

[0021] 2.37 <Nd1<2.55,1.23<Nd2<1.44,1.23<Nd3<1.44,2.37<Nd4<2.55,1.23<Nd5<1.44,2.37<Nd6<2.55。

[0022] In the above technical solution, the dispersion coefficients of the first lens to the sixth lens at the d-line are Vd1-Vd6 respectively, satisfying:

[0023] 12 <Vd1<16,90<Vd2<102,90<Vd3<102,12<Vd4<16,90<Vd5<102,12<Vd6<16。

[0024] In the above technical solution, the dual-band continuously zooming beam expander lens has the following features when expanding at 5.8X:

[0025] The distance between the first lens and the second lens is 14 mm.

[0026] The distance between the third lens and the fourth lens is 6.83 mm.

[0027] The distance between the fourth lens and the fifth lens is 233.2 mm.

[0028] In the above technical solution, the dual-band continuously zooming beam expander lens has the following features when expanding at 3.5X:

[0029] The distance between the first lens and the second lens is 62.8 mm.

[0030] The distance between the third lens and the fourth lens is 15.2 mm.

[0031] The distance between the fourth lens and the fifth lens is 176.05 mm.

[0032] In the above technical solution, the dual-band continuously zooming beam expander lens has the following features when expanding at 1X:

[0033] The distance between the first lens and the second lens is 170.8 mm.

[0034] The distance between the third lens and the fourth lens is 18.98 mm.

[0035] The distance between the fourth lens and the fifth lens is 64.2 mm.

[0036] In the above technical solution, the incident laser aperture is 20 mm.

[0037] In the above technical solution, the aperture of the image-side laser output varies continuously from 20 mm to 160 mm.

[0038] The present invention has the following beneficial effects:

[0039] The dual-band continuously zooming and beam expanding lens of the present invention can realize continuous zooming and beam expanding of the same aperture in the dual bands of 1.064μm and medium-wave 3.8μm. The span of the band is large, which can meet the ranging needs of 1.064μm laser and the infrared auxiliary lighting needs of 3.8μm medium-wave laser. The common aperture design of the two bands can effectively reduce the volume and reduce the weight. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0041] Figure 1 This is a schematic diagram of the 5.8X beam expansion optical path of the dual-band continuously zooming beam expander lens of the present invention.

[0042] Figure 2 This is a schematic diagram of the 3.5X beam expansion optical path of the dual-band continuous zoom beam expander lens of the present invention.

[0043] Figure 3 This is a schematic diagram of the beam expansion optical path of the dual-band continuously zooming beam expander lens 1X of the present invention.

[0044] Figure 4 This is the MTF curve of the dual-band continuous zoom beam expander lens of the present invention with a 5.8X beam expansion of 1.064μm.

[0045] Figure 5 This is the MTF curve of the dual-band continuously zooming beam expander lens of the present invention with a 5.8X beam expansion at 3.8μm.

[0046] Figure 6 This is the MTF curve of the dual-band continuously zooming beam expander lens of the present invention with a 3.5X beam expansion of 1.064μm.

[0047] Figure 7 This is the MTF curve of the dual-band continuously zooming beam expander lens of the present invention with a 1X beam expansion of 1.064μm.

[0048] The reference numerals in the figures indicate:

[0049] 1-first lens; 2-second lens; 3-third lens; 4-fourth lens; 5-fifth lens; 6-sixth lens. DETAILED DESCRIPTION

[0050] This invention provides a dual-band laser beam expander lens covering the 1.064μm and 3.8μm wavelengths. It achieves continuously variable beam expansion from 1X to 5.8X for 1.064μm lasers and 5.8X for medium-wavelength 3.8μm lasers. The incident laser enters from the object side with a 20mm aperture, while the exiting laser aperture on the image side continuously varies from 20mm to 160mm.

[0051] The present invention will be described in detail below with reference to the accompanying drawings.

[0052] like Figure 1-3 As shown, the dual-band continuously zooming and beam expanding lens of the present invention comprises: a lens body; the lens body comprises: a first lens 1, a second lens 2, a third lens 3, a fourth lens 4, a fifth lens 5, and a sixth lens 6, arranged coaxially from front to back along the optical axis from the object side to the image side. The focal lengths of the first lens 1, the fourth lens 4, and the sixth lens 6 are all positive, while the focal lengths of the second lens 2, the third lens 3, and the fifth lens 5 are all negative. The first lens 1 forms a front fixed lens group and remains stationary during zooming; the second lens 2 and the third lens 3 form a zoom lens group, and the fourth lens 4 forms a compensating lens group; the fifth lens 5 and the sixth lens 6 form a rear fixed lens group. The focal length f1 of the front fixed lens group is positive, the focal length f2 of the zoom lens group is negative, the focal length f3 of the compensating lens group is positive, and the focal length f4 of the rear fixed lens group is positive.

[0053] Nd1-Nd6 represent the refractive indices of the first lens 1 to the sixth lens 6 at the d-line, and Vd1-Vd6 represent the dispersion coefficients of the first lens 1 to the sixth lens 6 at the d-line. The dual-band continuously zooming beam expander lens of the present invention satisfies the following conditions:

[0054] 2.37 <Nd1<2.55,12<Vd1<16,1.23<Nd2<1.44,90<Vd2<102,1.23<Nd3<1.44,90<Vd3<102,2.37<Nd4<2.55,12<Vd4<16,1.23<Nd5<1.44,90<Vd5<102,2.37<Nd6<2.55,12<Vd6<16。

[0055] The parameters of the dual-band continuous zoom beam expander lens of the present invention are shown in Table 1.

[0056] Table 1: Parameters of dual-band continuously zoom laser beam expander lens

[0057] surface Curvature radius (mm) Thickness (mm) Refractive index dispersion coefficient OBJ Subject surface flat Infinity 1 First lens 1 -100.03 6 2.37 15.3 -80.89 L 2 Second lens 2 -23.55 5 1.43 95 173.55 8 3 Third lens 3 -70 5 1.43 95 127.5 M 4 Fourth lens 4 253.4 8 2.37 15.3 -244 N 5 Fifth lens 5 -79.5 11 1.43 95 flat 5 6 Sixth lens 6 -707.8 17 2.37 15.3 -148.3

[0058] The dual-band continuously zooming beam expander lens of this invention features a zoom lens group and a compensating lens group that move back and forth along the optical axis. The relative movement between the zoom lens group and the compensating lens group allows for adjustable beam expansion magnification of the laser beam emitted from the lens body. This relative movement enables continuous zooming of 1x to 5.8x for 1.064μm lasers and 5.8x for medium-wavelength 3.8μm lasers.

[0059] In the dual-band continuously zooming beam expander lens of the present invention, the spacing between the front fixed lens group and the zoom lens group is L, the spacing between the zoom lens group and the compensating lens group is M, and the spacing between the compensating lens group and the rear fixed lens group is N. Specifically, L is the spacing between the first lens 1 and the second lens 2, M is the spacing between the third lens 3 and the fourth lens 4, and N is the spacing between the fourth lens 4 and the fifth lens 5. The spacing between the lens groups for 5.8X, 3.5X, and 1X beam expansion is shown in Table 2.

[0060] Table 2: Intervals between groups at different beam expansion ratios

[0061] L(mm) M (mm) N(mm) 5.8X beam expansion 14 6.83 233.2 3.5X beam expansion 62.8 15.2 176.05 1X beam expansion 170.8 18.98 64.2

[0062] like Figure 4-7 As shown in the MTF curve obtained by applying the dual-band continuous zoom beam expander lens of the present invention to expand the beam, it can be seen that the dual-band continuous zoom beam expander lens of the present invention can achieve 1.064μm and medium-wave 3.8μm dual-band co-aperture continuous zoom beam expansion, involving a large band span, which can meet both the ranging of 1.064μm laser and the infrared auxiliary lighting of 3.8μm medium-wave laser. The co-aperture design of the two bands can effectively reduce the volume and reduce the weight.

[0063] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A dual-band continuously zooming beam expander lens, characterized in that: include: A lens body; the lens body comprises six lenses; the lens body comprises the following lenses, which are coaxially arranged in order from front to back along the optical axis from the object side to the image side: a first lens (1), a second lens (2), a third lens (3), a fourth lens (4), a fifth lens (5), and a sixth lens (6); The first lens (1) is a meniscus positive lens, and the concave surface of the first lens (1) faces the incident direction of the laser; the first lens (1) includes two surfaces S1 and S2, wherein the curvature radius of the S1 surface R1 = -100.03 mm; the curvature radius of the S2 surface R2 = -80.89 mm; the center thickness d1 between the two surfaces on the optical axis = 6 mm; The second lens (2) is a double concave negative lens; the second lens (2) includes two surfaces S3 and S4, wherein the curvature radius of the S3 surface R3 = -23.55 mm; the curvature radius of the S4 surface R4 = 173.55 mm; the center thickness d2 between the two surfaces on the optical axis = 5 mm; The third lens (3) is a double concave negative lens; the third lens (3) includes two surfaces, S5 and S6, wherein the curvature radius of the S5 surface is R5 = -70 mm; the curvature radius of the S6 surface is R6 = 127.5 mm; the center thickness d3 between the two surfaces on the optical axis is 5 mm; The fourth lens (4) is a biconvex positive lens; the fourth lens (4) includes two surfaces S7 and S8, wherein the curvature radius of the S7 surface R7 = 253.4 mm; the curvature radius of the S8 surface R8 = -244 mm; the center thickness d4 between the two surfaces on the optical axis = 8 mm; The fifth lens (5) is a plano-concave negative lens, and the concave surface of the fifth lens (5) faces the incident direction of the laser; the fifth lens (5) includes two surfaces, S9 and S10, wherein the curvature radius of the S9 surface R9 = -79.5 mm; the curvature radius of the S10 surface R10 = ∞; the center thickness d5 between the two surfaces on the optical axis = 11 mm; The sixth lens (6) is a meniscus convex positive lens, and the concave surface of the sixth lens (6) faces the incident direction of the laser; the sixth lens (6) includes two surfaces S11 and S12, wherein the curvature radius of the S11 surface R11 = -707.8 mm; the curvature radius of the S12 surface R12 = -148.3 mm; the center thickness d6 between the two surfaces on the optical axis = 17 mm; The first lens (1) is a front fixed lens group, which remains stationary when changing magnification, and has a positive focal length f1; The second lens (2) and the third lens (3) are a zoom lens group, and the focal length f2 is negative; The fourth lens (4) is a compensation lens group, and the focal length f3 is positive; The fifth lens (5) and the sixth lens (6) are a rear fixed lens group, and the focal length f4 is positive; The zoom lens group and the compensation lens group can be moved forward and backward along the optical axis respectively, so that the beam expansion magnification of the output laser of the lens body can be adjusted.

2. The dual-band continuously zooming beam expander lens according to claim 1, characterized in that: The interval between the first lens (1) and the second lens (2) is 14-170.8 mm; the interval between the second lens (2) and the third lens (3) is 8 mm; the interval between the third lens (3) and the fourth lens (4) is 6.83-18.98 mm; the interval between the fourth lens (4) and the fifth lens (5) is 64.2-233.2 mm; and the interval between the fifth lens (5) and the sixth lens (6) is 5 mm.

3. The dual-band continuously zooming beam expander lens according to claim 1, characterized in that: The d-light refractive indices of the first lens (1) to the sixth lens (6) are Nd1-Nd6, respectively, satisfying: 2.37< Nd1<2.55, 1.23< Nd2<1.44, 1.23< Nd3<1.44, 2.37< Nd4<2.55, 1.23< Nd5<1.44, 2.37< Nd6<2.

55.

4. The dual-band continuously zooming beam expander lens according to claim 1, wherein: The dispersion coefficients of the first lens (1) to the sixth lens (6) at the d-line are Vd1-Vd6 respectively, satisfying: 12< Vd1<16, 90< Vd2<102, 90< Vd3<102, 12< Vd4<16, 90< Vd5<102, 12< Vd6<16.

5. The dual-band continuously zooming beam expander lens according to any one of claims 1 to 4, characterized in that: This dual-band continuous zoom beam expander lens has the following features when expanding at 5.8X: The distance between the first lens (1) and the second lens (2) is 14 mm. The distance between the third lens (3) and the fourth lens (4) is 6.83 mm. The distance between the fourth lens (4) and the fifth lens (5) is 233.2 mm.

6. The dual-band continuously zooming beam expander lens according to any one of claims 1 to 4, characterized in that: This dual-band continuous zoom beam expander lens has the following features when expanding at 3.5X: The distance between the first lens (1) and the second lens (2) is 62.8 mm. The distance between the third lens (3) and the fourth lens (4) is 15.2 mm. The interval between the fourth lens (4) and the fifth lens (5) is 176.05 mm.

7. The dual-band continuously zooming beam expander lens according to any one of claims 1 to 4, characterized in that: This dual-band continuous zoom beam expander lens is: The distance between the first lens (1) and the second lens (2) is 170.8 mm. The distance between the third lens (3) and the fourth lens (4) is 18.98 mm. The distance between the fourth lens (4) and the fifth lens (5) is 64.2 mm.

8. The dual-band continuously zooming beam expander lens according to any one of claims 1 to 4, characterized in that: The incident laser aperture is 20 mm.

9. The dual-band continuously zooming beam expander lens according to any one of claims 1 to 4, characterized in that: The image-side laser aperture varies continuously from 20mm to 160mm.

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