Large-aperture high-magnification laser beam expander

Abstract

The present invention discloses a large-aperture and high-magnification laser beam expander, which relates to the technical field of optical precision instruments; it includes a first-stage beam expander, a second-stage beam expander, and a third-stage beam expander; the first-stage beam expander includes a first lens, a second lens, and a third lens; the second-stage beam expander includes a fourth lens, a fifth lens, and a sixth lens; the third-stage beam expander includes a seventh convex mirror and an eighth concave mirror; the system also includes a first and a second folding mirror; the first-stage beam expander and the second-stage beam expander are coaxial; the first folding mirror is obliquely placed on the main optical axis of the second-stage beam expander; the second folding mirror is obliquely placed on the main optical axis of the third-stage beam expander; the main optical axes of the second-stage beam expander and the third-stage beam expander are parallel but not coincident; the incident light passes through the first-stage beam expander and the second-stage beam expander in sequence, then passes through the first and second folding mirrors, and exits through the third-stage beam expander. The laser beam expander of the present invention has a reasonable distribution of beam expansion magnification, avoiding the large influence caused by temperature changes due to the large beam expansion magnification of a single beam expander.

Description

Technical Field

[0001] The present invention relates to the technical field of optical precision instruments, and particularly to a large-aperture and high-magnification laser beam expander. Background Art

[0002] Lasers are widely used in various fields, such as laser guidance, laser weapons, laser spectroscopy research, laser medicine and biology research, atmospheric detection, etc. Lasers have high directivity, which enables them to effectively transmit over long distances while ensuring extremely high power density upon focusing, and the energy output is highly concentrated. In applications, a laser beam expander is often required to expand the laser diameter to the required diameter before transmitting it to the target. Currently, there are certain difficulties in the design and research of high-magnification laser beam expanders. Since the optical lenses in the laser beam expander are easily deformed due to temperature changes, and the mechanical parts in the laser beam expander are also deformed by temperature changes, the laser beam expander has low precision and large errors.

[0003] The larger the aperture of the laser beam expander and the greater the expansion ratio, the more easily the mechanical parts of the beam expander and the optical lenses of the beam expander itself are deformed due to changes in the external environmental temperature, thereby affecting the diameter and parallelism of the expanded laser beam, and the accuracy decreases.

[0004] Therefore, it is necessary to design a large-aperture and high-magnification laser beam expander to solve the above-mentioned technical problems. Summary of the Invention

[0005] In view of the above problems, the present invention provides a large-aperture and high-magnification laser beam expander, which realizes high-magnification expansion of the laser, corrects the errors caused by processing accuracy, analyzes the temperature of the beam expander and performs compensation, and corrects the errors caused by temperature to ensure the accurate expansion ratio and parallelism of the laser.

[0006] The technical solution adopted by the present invention is as follows:

[0007] A large-aperture and high-magnification laser beam expander, comprising a primary beam expander, a secondary beam expander, and a tertiary beam expander;

[0008] The primary beam expander includes a first lens, a second lens, and a third lens;

[0009] The secondary beam expander includes a fourth lens, a fifth lens, and a sixth lens;

[0010] The tertiary beam expander includes a seventh convex mirror and an eighth concave mirror;

[0011] The system further includes a first folding mirror and a second folding mirror;

[0012] The primary beam expander and the secondary beam expander are coaxial;

[0013] The first folding mirror is placed obliquely on the main optical axis of the secondary beam expander;

[0014] The second folding mirror is placed obliquely on the main optical axis of the tertiary beam expander;

[0015] The main optical axes of the secondary beam expander and the tertiary beam expander are parallel but not coincident;

[0016] Further, the incident light is transmitted through the primary beam expander;

[0017] Further, after passing through the primary beam expander, the incident light passes through the secondary beam expander;

[0018] Further, after passing through the secondary beam expander, the incident light passes through two folding mirrors and then through the tertiary beam expander.

[0019] Preferably, the materials of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens are all fused silica, and the materials of the folding mirrors, the seventh convex mirror, and the eighth concave mirror are all glass-ceramics;

[0020] Preferably, the curved surfaces of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens are all spherical surfaces;

[0021] Preferably, the reflecting surfaces of the seventh convex mirror and the eighth concave mirror are both parabolic surfaces;

[0022] Preferably, the material of the connecting rod between the seventh convex mirror and the eighth concave mirror is invar;

[0023] The distance between the first lens and the second lens is 3 ± 0.02 mm;

[0024] The distance between the second lens and the third lens is 39.6 ± 0.02 mm;

[0025] The distance between the third lens and the fourth lens is 300 ± 0.1 mm;

[0026] The distance between the fourth lens and the fifth lens is 177.9 ± 0.02 mm;

[0027] The distance between the fifth lens and the sixth lens is 11 ± 0.02 mm;

[0028] The distance between the sixth lens and the first folding mirror is 80 ± 0.1 mm;

[0029] The distance between the first folding mirror and the second folding mirror is 700 ± 0.1 mm;

[0030] The distance between the second folding mirror and the seventh convex mirror is 1400 ± 1 mm;

[0031] The distance between the seventh convex mirror and the eighth concave mirror is 1104 ± 0.02 mm;

[0032] The first-stage beam expander expands the diameter of the incident light by 2 times;

[0033] The second-stage beam expander expands the diameter of the incident light by 4 times;

[0034] The third-stage beam expander expands the diameter of the incident light by 12.5 times.

[0035] The advantages of the present invention are:

[0036] A large-aperture and high-magnification laser beam expander of the present invention, the incident light is transmitted through the first-stage beam expander in sequence, the diameter of the incident light is expanded by 2 times, through the second-stage beam expander, the diameter of the incident light is cumulatively expanded by 8 times, and then through the third-stage beam expander for reflection and beam expansion, the diameter of the incident light is cumulatively expanded by 100 times, thus realizing high-magnification beam expansion of the laser; the beam expansion ratio of the laser beam expander of the present invention is reasonably distributed, avoiding the large influence caused by temperature change due to the large beam expansion ratio of a single beam expander. For the third-stage beam expander with a large aperture, its connecting rod member is made of invar material, reducing the influence caused by temperature change of mechanical parts and reducing the deformation of optical lenses caused by the deformation of mechanical parts. Brief Description of the Drawings

[0037] Figure 1 It is a schematic structural diagram of the first-stage beam expander of the large-aperture and high-magnification laser beam expander according to the embodiment of the present invention.

[0038] Figure 2 It is a schematic structural diagram of the second-stage beam expander of the large-aperture and high-magnification laser beam expander according to the embodiment of the present invention.

[0039] Figure 3 It is a schematic structural diagram of the third-stage beam expander of the large-aperture and high-magnification laser beam expander according to the embodiment of the present invention.

[0040] Figure 4 It is a schematic overall structural diagram of the large-aperture and high-magnification laser beam expander according to the embodiment of the present invention.

[0041] Figure 5 It is a central field wavefront diagram of the first-stage beam expander of the large-aperture and high-magnification laser beam expander according to the embodiment of the present invention.

[0042] Figure 6 It is a central field wavefront diagram of the second-stage beam expander of the large-aperture and high-magnification laser beam expander according to the embodiment of the present invention.

[0043] Figure 7 It is a central field wavefront diagram of the third-stage beam expander of the large-aperture and high-magnification laser beam expander according to the embodiment of the present invention.

[0044] Figure 8 It is a central field wavefront diagram of the overall structure of the large-aperture and high-magnification laser beam expander according to the embodiment of the present invention.

[0045] In the figure: the first lens 1, the second lens 2, the third lens 3, the fourth lens 4, the fifth lens 5, the sixth lens 6, the seventh convex mirror 7, the eighth concave mirror, the first folding mirror 9, and the second folding mirror 10. Specific embodiments

[0046] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments.

[0047] Embodiment 1.

[0048] As Figure 1-4 shown, a large-aperture high-magnification laser beam expander includes a first-stage beam expander, a second-stage beam expander, and a third-stage beam expander; the first-stage beam expander includes the first lens 1, the second lens 2, and the third lens 3; the second-stage beam expander includes the fourth lens 4, the fifth lens 5, and the sixth lens 6; the third-stage beam expander includes the seventh convex mirror 7 and the eighth concave mirror 8; the system further includes the first folding mirror 9 and the second folding mirror 10; the first-stage beam expander and the second-stage beam expander are coaxial; the first folding mirror 9 is inclined on the main optical axis of the second-stage beam expander; the second folding mirror 10 is inclined on the main optical axis of the third-stage beam expander; the main optical axes of the second-stage beam expander and the third-stage beam expander are parallel but not coincident; the incident light passes through the first-stage beam expander and the second-stage beam expander in sequence, then passes through the first folding mirror 9 and the second folding mirror 10, and exits through the third-stage beam expander.

[0049] The materials of the first lens 1, the second lens 2, the third lens 3, the fourth lens 4, the fifth lens 5, and the sixth lens 6 are all quartz glass, and the materials of the first folding mirror 9, the second folding mirror 10, the seventh convex mirror 7, and the eighth concave mirror 8 are all glass-ceramics.

[0050] The curved surfaces of the first lens 1, the second lens 2, the third lens 3, the fourth lens 4, the fifth lens 5, and the sixth lens 6 are all spherical surfaces; the reflecting surfaces of the seventh convex mirror 7 and the eighth concave mirror 8 are all parabolic surfaces.

[0051] The connecting rod member between the seventh convex mirror 7 and the eighth concave mirror 8 is made of invar.

[0052] As Figure 4 shown, the first-stage beam expander expands the diameter of the incident light by 2 times; the second-stage beam expander expands the diameter of the incident light by 4 times; the third-stage beam expander expands the diameter of the incident light by 12.5 times.

[0053] In this embodiment, the system includes two folding mirrors, namely the first folding mirror 9 and the second folding mirror 10. To save space, the first folding mirror 9 and the second folding mirror 10 are symmetrically placed. The first-stage beam expander, the second-stage beam expander, and the first folding mirror 9 are coaxially placed, and the second folding mirror 10 and the third-stage beam expander are coaxially placed.

[0054] Next, a detailed description of the first-stage beam expander, the second-stage beam expander, and the third-stage beam expander will be given. In the description, the optical parameters (curvature radius, conic coefficient) are listed according to the rules of geometric optics symbols.

[0055] In one embodiment, the first-stage beam expander consists of a first lens 1, a second lens 2, and a third lens 3. Its structure is as Figure 1 shown. The beam expansion ratio of the first-stage beam expander is 2 times. The laser emits a 9-mm laser beam, which passes through the first lens 1, the second lens 2, and the third lens 3 of the first-stage beam expander in sequence and then exits as 18-mm parallel light. The incident light field angle of the first-stage beam expander is ±0.0286°, and the wavefront RMS of the central field of view of the first-stage beam expander is 0.0014λ. The parameters of each component in the first-stage beam expander are as follows:

[0056] Element Remark Radius of curvature Thickness Conic coefficient Material 1 First lens 1 <![CDATA[R1(80)]]> 2.5 0 SILICA <![CDATA[R2(20)]]> 0 2 First lens 2 <![CDATA[R1(229.77)]]> 3 0 SILICA <![CDATA[R2(102.519)]]> 0 3 First lens 3 <![CDATA[R1(-104.23)]]> 5.5 0 SILICA <![CDATA[R2(-32.66)]]> 0

[0057] Among them, as Figure 1 shown, the air gap between the first lens and the second lens on the optical axis is 3 mm, and the air gap between the second lens and the third lens on the optical axis is 39.6 mm.

[0058] In one embodiment, the second-stage beam expander consists of a fourth lens 4, a fifth lens 5, and a sixth lens 6. Its structure is as Figure 2 shown. The beam expansion ratio of the second-stage beam expander is 4 times. The 18-mm outgoing light emitted from the first-stage beam expander is incident on the second-stage beam expander and exits as 72-mm parallel light after passing through the fourth lens 4, the fifth lens 5, and the sixth lens 6 of the second-stage beam expander in sequence. The incident light field angle of the second-stage beam expander is ±0.0143°, and the wavefront RMS of the central field of view of the second-stage beam expander is 0.0094λ. The parameters of each component in the second-stage beam expander are as follows:

[0059] Element Remark Radius of curvature Thickness Conic coefficient Material 1 Fourth lens 4 <![CDATA[R1(111.34)]]> 5.5 0 SILICA <![CDATA[R2(28.164)]]> 0 2 Fifth lens 5 <![CDATA[R1(-538.1)]]> 15 0 SILICA <![CDATA[R2(262.128)]]> 0 3 Sixth lens 6 <![CDATA[R1(1066.025)]]> 20 0 SILICA <![CDATA[R2(-93)]]> 0

[0060] Among them, as Figure 2 shown, the air gap between the fourth lens 4 and the fifth lens 5 on the optical axis is 177.91 mm, and the air gap between the fifth lens 5 and the sixth lens 6 on the optical axis is 20 mm.

[0061] In one embodiment, the third-stage beam expander consists of a seventh convex mirror 7 and an eighth concave mirror 8. Its structure is as Figure 3As shown, the beam expansion ratio of the three-stage beam expander is 12.5 times. The 72mm output light emitted from the first and second-stage beam expanders is incident on the third-stage beam expander, and after passing through the seventh convex mirror 7 and the eighth concave mirror 8 of the third-stage beam expander in sequence, it is emitted as 900mm parallel light. The incident light field angle of the third-stage beam expander is ±0.00357°, and the wavefront RMS of the central field of the third-stage beam expander is 0λ. The parameters of each component in the third-stage beam expander are as follows:

[0062] Element Remark Radius of curvature Thickness Conic coefficient Material 1 Seventh convex mirror 7 <![CDATA[R1(-2400)]]> -1 Microcrystal 2 Eighth concave mirror 8 <![CDATA[R1(-192)]]> -1 Microcrystal

[0063] Among them, the air gap between the seventh convex mirror 7 and the eighth concave mirror 8 on the optical axis is 1104mm, and the reflecting surfaces of the seventh convex mirror 7 and the eighth concave mirror 8 are paraboloids.

[0064] In one embodiment, as Figure 4 shown, the air gap between the sixth lens 6 and the first folding mirror 9 on the optical axis is 80mm, the air gap between the first folding mirror 9 and the second folding mirror 10 on the optical axis is 700mm, and the air gap between the second folding mirror 10 and the seventh convex mirror 7 on the optical axis is 1400mm. The materials of the first folding mirror 9 and the second folding mirror 10 are glass-ceramics.

[0065] Figure 5 shows the wavefront diagram of the central field of the first-stage beam expander of the large-aperture high-magnification laser beam expander according to the embodiment of the present invention.

[0066] Figure 6 shows the wavefront diagram of the central field of the second-stage beam expander of the large-aperture high-magnification laser beam expander according to the embodiment of the present invention.

[0067] Figure 7 shows the wavefront diagram of the central field of the third-stage beam expander of the large-aperture high-magnification laser beam expander according to the embodiment of the present invention.

[0068] Figure 8 shows the wavefront diagram of the central field of the overall structure of the large-aperture high-magnification laser beam expander according to the embodiment of the present invention.

[0069] The above is only the preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent replacements or changes, and should be covered by the protection scope of the present invention.

Claims

1. A large-aperture high-magnification laser beam expander, characterized in that, It includes a primary beam expander, a secondary beam expander, and a tertiary beam expander; the primary beam expander includes a first lens (1), a second lens (2), and a third lens (3); the secondary beam expander includes a fourth lens (4), a fifth lens (5), and a sixth lens (6); the tertiary beam expander includes a seventh convex mirror (7) and an eighth concave mirror (8); the large-aperture high-magnification laser beam expander further includes a first folding mirror (9) and a second folding mirror (10); the primary beam expander and the secondary beam expander are coaxial; the first folding mirror (9) is inclined to the main optical axis of the secondary beam expander; the second folding mirror (10) is inclined to the main optical axis of the tertiary beam expander; the main optical axes of the secondary beam expander and the tertiary beam expander are parallel but not coincident; the incident light passes through the primary beam expander and the secondary beam expander in sequence, then passes through the first folding mirror (9) and the second folding mirror (10), and exits through the tertiary beam expander; the distance between the first lens (1) and the second lens (2) is 3 ± 0.02 mm; the distance between the second lens (2) and the third lens (3) is 39.6 ± 0.02 mm; the distance between the third lens (3) and the fourth lens (4) is 300 ± 0.1 mm; the distance between the fourth lens (4) and the fifth lens (5) is 177.9 ± 0.02 mm; the distance between the fifth lens (5) and the sixth lens (6) is 11 ± 0.02 mm; the distance between the first folding mirror (9) and the second folding mirror (10) is 700 ± 0.1 mm; the distance between the second folding mirror (10) and the seventh convex mirror (7) is 1400 ± 1 mm; the distance between the seventh convex mirror (7) and the eighth concave mirror (8) is 1104 ± 0.02 mm; the primary beam expander expands the diameter of the incident light by a factor of 2; the secondary beam expander expands the diameter of the incident light by a factor of 4; the tertiary beam expander expands the diameter of the incident light by a factor of 12.

5.

2. The large-aperture high-magnification laser beam expander according to claim 1, wherein The materials of the first lens (1), the second lens (2), the third lens (3), the fourth lens (4), the fifth lens (5), and the sixth lens (6) are all fused silica glass, and the materials of the first folding mirror (9), the second folding mirror (10), the seventh convex mirror (7), and the eighth concave mirror (8) are all glass-ceramics.

3. The large-aperture high-magnification laser beam expander according to claim 1, characterized in that, The curved surfaces of the first lens (1), the second lens (2), the third lens (3), the fourth lens (4), the fifth lens (5), and the sixth lens (6) are all spherical surfaces; the reflecting surfaces of the seventh convex mirror (7) and the eighth concave mirror (8) are all parabolic surfaces.

4. The large-aperture high-magnification laser beam expander according to claim 1, wherein The connecting rod member between the seventh convex mirror (7) and the eighth concave mirror (8) is made of Invar.

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