Wide-spectrum laser zoom-beam collimation optical system

Abstract

The application discloses a wide-spectrum laser zooming and expanding collimating optical system, which comprises coaxially arranged in sequence along the light transmission direction a fixed lens group for focusing light, a zooming lens group for realizing expansion ratio change, a compensating lens group for compensating the movement of the zooming lens group and a protective window sheet, the optical power of the fixed lens group is positive, the optical power of the zooming lens group is negative, the optical power of the compensating lens group is positive, and the protective window sheet has no optical power. The application covers the wavelength range from 355nm to 1064nm, and simultaneously realizes laser expanding and collimating in the ultraviolet-visible-near infrared wavelength range. The wide-spectrum basically includes the working wavelength range of most current laser radars, laser ranging and laser processing systems; the incident laser with a beam diameter of not more than 5mm can be collimated, and the maximum zooming ratio is 12 times. The application meets the use in various fields such as current laser radars, laser ranging, laser processing and laser interferometers.

Description

Technical Field

[0001] This invention belongs to the field of laser technology and relates to a broadband laser variable magnification beam expansion and collimation optical system. Background Technology

[0002] For lidar systems, such as atmospheric lidar systems, to increase echo signal energy and detection altitude, it is usually necessary to expand and collimate the emitted laser beam to improve the laser divergence angle and achieve optimal detection efficiency. However, different lidar systems have different initial laser spot sizes and divergence angles, and the receiving system's field of view also varies. If a fixed-focus beam expander and collimator system is used, different magnification beam expander and collimator systems need to be designed and manufactured for different lidar systems, which not only increases costs. On the other hand, when the actual lidar operation requires changing the laser divergence angle to achieve different detection altitudes / distances, a beam expander and collimator system with the corresponding magnification must also be replaced. The above situation cannot meet the current demand for multiple atmospheric lidar systems to work together to achieve a wider detection range and detect more atmospheric elements.

[0003] Similarly, in the field of laser processing, the emitted laser beam needs to be expanded and collimated first, and then focused and shaped using lenses such as focusing mirrors and integrating mirrors to achieve processes such as cutting, cladding, welding, and surface cleaning of the workpiece. Generally speaking, the better the collimation effect, the better the laser processing effect. However, to achieve a better collimation effect, it means increasing the aperture of the collimated spot. However, the aperture of focusing mirrors and other lenses is often limited, and the initial divergence angle of the emitted laser varies from laser to laser. Therefore, a beam expansion and collimation system with variable magnification is urgently needed to meet different laser collimation requirements.

[0004] Furthermore, different lidar systems and different laser processing equipment emit lasers with different wavelengths. Sometimes, a single lidar system may even emit lasers from several different wavelengths simultaneously. If the laser beam expander and collimator system is designed to collimate only a single wavelength, collimating different wavelengths of laser light will require adjusting and changing the optical parameters of the beam expander system, or even redesigning and remanufacturing the beam expander and collimator optical system. With the development of multispectral / hyperspectral and color lidar, it is not only necessary to continuously expand and collimate single-wavelength lasers, but also to simultaneously collimate multiple wavelengths of laser light, even covering the ultraviolet-visible-near-infrared supercontinuum, in order to detect multispectral information of the target. Therefore, a variable-magnification laser beam expander and collimator system also needs to have a wide-spectrum achromatic capability to meet the application requirements of different wavelengths of laser beam expander and collimator.

[0005] Beam-expanding collimating optical systems are mainly divided into Keplerian and Galilean structures. Keplerian structures have a real focal point and are generally not used in laser technology applications to avoid excessively high focused spot energy density, which could damage the lenses. Variable-magnification Galilean structures can be further divided into three types based on the sign of the optical power of the fixed lens group, the variable-magnification lens group, and the compensation lens group: "negative-positive-negative," "negative-negative-positive," and "positive-negative-positive," taking into account translation distance, magnification, and aberration correction. This invention adopts a "positive-negative-positive" structure.

[0006] Reference 1 (Design of Laser Zoom Beam Expanding Optical System_Shan Juan) describes a laser zoom beam expanding system with a Galilean structure, an incident beam diameter not exceeding 5mm, and a continuous zoom range of 2X-6X. However, this laser zoom beam expanding system has too low a magnification, failing to meet the current requirements of lidar for laser divergence angle compression.

[0007] Reference 2 (Design of Laser Zoom Collimation and Expanding System_Wang Peifang) describes a laser zoom beam expanding system with a Galilean structure, an incident beam diameter of 1 mm, a zoom range of 4X-24X continuous zoom, and an operating wavelength of 1064 nm. This laser zoom beam expanding system has an excessively small incident beam diameter, which does not meet the requirements of most current lasers, especially high-power output beam sizes. Furthermore, its single-wavelength operation prevents its application in lidar systems across different wavelength bands.

[0008] Regarding domestic patents, patent CN105093538A published by Qu Yingli et al. in 2017 describes a laser zoom beam expander system with a Galilean structure. The zoom range is 2X-8X, operating in the 10.6µm far-infrared band, but it lacks the ability to simultaneously expand and collimate beams across multiple wavelengths. Neither the zoom range nor the wavelength range meets the current requirements of lidar. Summary of the Invention

[0009] To address the limitations of current laser zoom beam expander systems in simultaneously meeting the operational requirements of laser processing, lidar, and other related fields, particularly atmospheric lidar and multispectral / hyperspectral lidar, this invention provides a broadband laser zoom beam expander collimating optical system. Its incident aperture meets the output beam requirements of current laser systems; it boasts a large zoom range to satisfy the divergence angle requirements of different lidar systems and allows for on-the-fly magnification adjustments; and it achieves chromatic aberration correction across a broad ultraviolet-visible-near-infrared spectral range, enabling simultaneous collimation of lasers in different wavelength bands.

[0010] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0011] A broadband laser variable magnification beam expander collimating optical system includes a fixed lens group for focusing light, which is coaxially arranged along the light transmission direction; a variable magnification lens group for changing the beam expansion magnification; a compensating lens group for compensating for the movement of the variable magnification lens group; and a protective window. The optical power of the fixed lens group is positive, the optical power of the variable magnification lens group is negative, the optical power of the compensating lens group is positive, and the protective window has no optical power.

[0012] The fixed lens group described above includes a first lens, a second lens, and a third lens arranged sequentially along the light transmission direction, with the optical powers of the first lens, the second lens, and the third lens being positive, negative, and positive, respectively.

[0013] The zoom lens group described above includes a fourth lens and a fifth lens arranged sequentially along the light transmission direction, with the optical powers of the fourth lens and the fifth lens being negative and positive, respectively.

[0014] The compensation lens group described above includes a sixth lens, a seventh lens, an eighth lens, and a ninth lens arranged sequentially along the light transmission direction. The optical powers of the sixth lens, the seventh lens, the eighth lens, and the ninth lens are negative, positive, negative, and positive, respectively.

[0015] The protective window as described above is made of fused silica material.

[0016] As described above, the first lens is a meniscus positive lens, the second lens is a biconcave negative lens, the third lens is a meniscus positive lens, the fourth lens is a biconcave negative lens, the fifth lens is a biconvex positive lens, the sixth lens is a biconcave negative lens, the seventh lens is a biconvex positive lens, the eighth lens is a biconcave negative lens, and the ninth lens is a biconvex positive lens.

[0017] The focal lengths of each lens in the fixed lens group as described above are related to the focal length f of the fixed lens group. 固 The ratio between them satisfies the following condition: 0.8 ≤ |f1 / f 固 |≤1.2, 1.2≤|f2 / f 固 |≤1.8, 1.2≤|f3 / f 固 |≤1.8, where f1, f2, and f3 are the focal lengths of the first, second, and third lenses, respectively, and f 固 The focal length of the fixed lens group.

[0018] As mentioned above, the focal length of each lens in the zoom group is equal to the focal length f of the zoom group. 变 The ratio between them satisfies the following condition: 0.4 ≤ |f4 / f 变 |≤0.7, 1.3≤|f5 / f 变 |≤1.8, where f4 and f5 are the focal lengths of the fourth and fifth lenses, respectively. 变 It is the focal length of the zoom lens group.

[0019] As described above, the focal length and focal length f of each lens in the compensating lens group 补 The ratio between them satisfies the following condition: 0.2 ≤ |f6 / f 补 |≤0.4, 0.15≤|f7 / f 补 |≤0.3, 0.17≤|f8 / f 补 |≤0.3, 0.2≤|f9 / f 补 |≤0.35, where f6, f7, and f8 are the focal lengths of the sixth, seventh, and eighth lenses, respectively. 补 To compensate for the focal length of the lens group.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] This invention discloses a broadband laser variable magnification beam expander and collimator optical system covering a wavelength range from 355nm to 1064nm, while simultaneously achieving laser beam expander and collimator within the ultraviolet-visible-near-infrared wavelength range. The broadband spectrum essentially encompasses the operating wavelengths of most current lidar, laser ranging, and laser processing systems.

[0022] This invention discloses a broadband laser zoom beam expander and collimation optical system capable of collimating incident laser beams with a diameter not exceeding 5 mm, with a maximum zoom ratio of 12x. It meets the requirements for use in various fields such as lidar, laser ranging, laser processing, and laser interferometers.

[0023] The lenses used in the broadband laser zoom beam expander collimating optical system of this invention are all spherical lenses with suitable lens centering coefficients, which is beneficial for mass production and processing.

[0024] This invention provides a broadband laser zoom beam expander collimating optical system with a small zoom translation distance, which reduces the difficulty of mechanical structure design and manufacturing, and is beneficial for zooming driven by a motor.

[0025] The present invention provides a broadband laser zoom beam expander and collimator optical system with a root mean square wavefront difference of less than 1 / 4 wavelength in both the working band and zoom range, exhibiting excellent optical quality. Attached Figure Description

[0026] Figure 1 This is a cross-sectional schematic diagram of Embodiment 1 of the present invention at a magnification of 4x.

[0027] Figure 2 This is a cross-sectional schematic diagram of Embodiment 1 of the present invention at a magnification of 8x.

[0028] Figure 3 This is a cross-sectional schematic diagram of Embodiment 1 of the present invention at a magnification of 12x.

[0029] Figure 4aThis is the wavefront diagram at 355nm shortwavelength corresponding to a 4x magnification in Embodiment 1 of the present invention. In this diagram, 0.3550um is at 0.0000 (degrees), the wavefront to trough ratio is 0.3624, the RMS ratio is 0.0734, the plane is the image plane, the exit pupil diameter is 2.2402E01 mm, and the tilt removal ratio is X = 0.0000 and Y = -0.0000.

[0030] Figure 4b This is the wavefront diagram at 532nm shortwavelength corresponding to a 4x magnification in Embodiment 1 of the present invention. In this diagram, 0.5320um is at 0.0000 (degrees), the wavefront to trough ratio is 0.0878, the RMS is 0.0231, the plane is the image plane, the exit pupil diameter is 2.2402E01 mm, and the tilt removal is X = -0.0000 and Y = 0.0000.

[0031] Figure 4c This is the wavefront diagram at 1064nm (short wavelength) corresponding to a 4x magnification in Embodiment 1 of the present invention. The wavefront diagram shows 1.0640um at 0.0000 (degrees), peak to trough = 0.3695 waves, RMS = 0.0338 waves, plane: image plane, exit pupil diameter: 2.2402E01 mm, tilt removal: X = 0.0000, Y = 0.0000 waves.

[0032] Figure 5a This is the wavefront diagram at 355nm shortwavelength corresponding to 8x magnification in Embodiment 1 of the present invention. In this diagram, 0.3550um is at 0.0000 (degrees), the wavefront to trough ratio is 0.2623, the RMS ratio is 0.0407, the plane is the image plane, the exit pupil diameter is 4.2742E01 mm, and the tilt removal ratio is X = 0.0000 and Y = 0.0000.

[0033] Figure 5b This is the wavefront diagram at 532nm shortwavelength corresponding to 8x magnification in Embodiment 1 of the present invention. In this diagram, 0.5320um is at 0.0000 (degrees), the wavefront to trough ratio is 0.2444, the RMS ratio is 0.0264, the plane is the image plane, the exit pupil diameter is 4.2742E01 mm, and the tilt removal ratios are X = -0.0000 and Y = -0.0000.

[0034] Figure 5c This is the wavefront diagram at 1064nm (shortwavelength) corresponding to 8x magnification in Embodiment 1 of the present invention. The wavefront diagram shows 1.0640um at 0.0000 (degrees), peak to trough = 0.0255 waves, RMS = 0.0062 waves, plane: image plane, exit pupil diameter: 4.2742E01 mm, tilt removal: X = -0.0000, Y = -0.0000 waves.

[0035] Figure 6aThis is the wavefront diagram at 355nm shortwavelength corresponding to a magnification of 12x in Embodiment 1 of the present invention. In this diagram, 0.3550um is at 0.0000 (degrees), the wavefront to trough ratio is 0.7134, the RMS ratio is 0.1820, the plane is the image plane, the exit pupil diameter is 6.1400E01 mm, and the tilt removal ratio is X = 0.0000 and Y = 0.0000.

[0036] Figure 6b This is the wavefront diagram at 532nm shortwavelength corresponding to a magnification of 12x in Embodiment 1 of the present invention. In this diagram, 0.5320um is at 0.0000 (degrees), the wavefront to trough ratio is 0.5158, the RMS ratio is 0.1317, the plane is the image plane, the exit pupil diameter is 6.1400E01 mm, and the tilt removal ratio is X = 0.0000 and Y = 0.0000.

[0037] Figure 6c This is the wavefront diagram at 1064nm (shortwavelength) corresponding to a magnification of 12x in Embodiment 1 of the present invention. The wavefront diagram shows 1.0640um at 0.0000 (degrees), peak to trough = 0.2623 waves, RMS = 0.0407 waves, plane: image plane, exit pupil diameter: 4.2742E01 mm, tilt removal: X = 0.0000, Y = 0.0000 waves.

[0038] Figure 7 This is a cross-sectional schematic diagram of Embodiment 2 of the present invention at a magnification of 4x.

[0039] Figure 8 This is a cross-sectional schematic diagram of Embodiment 2 of the present invention at a magnification of 8x.

[0040] Figure 9 This is a cross-sectional schematic diagram of Embodiment 2 of the present invention at a magnification of 12x.

[0041] Figure 10a This is the wavefront diagram at 355nm shortwavelength corresponding to a 4x magnification in Embodiment 2 of the present invention. In this diagram, 0.3550um is at 0.0000 (degrees), the wavefront to trough ratio is 0.3113, the RMS is 0.0587, the plane is the image plane, the exit pupil diameter is 2.2284E01 mm, and the tilt removal is X = -0.0000 and Y = -0.0000.

[0042] Figure 10b This is the wavefront diagram at 532nm shortwavelength corresponding to a 4x magnification in Embodiment 2 of the present invention. In this diagram, 0.5320um is at 0.0000 (degrees), the wavefront to trough ratio is 0.0418, the RMS ratio is 0.0119, the plane is the image plane, the exit pupil diameter is 2.2284E01 mm, and the tilt removal is X = 0.0000 and Y = 0.0000.

[0043] Figure 10c This is the wavefront diagram at 1064nm (shortwavelength) corresponding to a 4x magnification in Embodiment 2 of the present invention. The wavefront diagram shows 1.0640um at 0.0000 (degrees), peak to trough = 0.4036 waves, RMS = 0.0391 waves, plane: image plane, exit pupil diameter: 2.2284E01 mm, tilt removal: X = 0.0000, Y = 0.0000 waves.

[0044] Figure 11a This is the wavefront diagram at 355nm shortwavelength corresponding to 8x magnification in Embodiment 2 of the present invention. In this diagram, 0.3550um is at 0.0000 (degrees), the wavefront to trough ratio is 0.2791, the RMS ratio is 0.0448, the plane is the image plane, the exit pupil diameter is 4.2642E01 mm, and the tilt removal ratio is X = 0.0000 and Y = 0.0000.

[0045] Figure 11b This is the wavefront diagram at 532nm shortwavelength corresponding to 8x magnification in Embodiment 2 of the present invention. In this diagram, 0.5320um is at 0.0000 (degrees), the wavefront to trough ratio is 0.1782, the RMS ratio is 0.0242, the plane is the image plane, the exit pupil diameter is 4.2642E01 mm, and the tilt removal ratios are X = -0.0000 and Y = -0.0000.

[0046] Figure 11c This is the wavefront diagram at 1064nm (shortwavelength) corresponding to an 8x magnification in Embodiment 2 of the present invention. The wavefront diagram shows 1.0640um at 0.0000 (degrees), peak to trough = 0.3157 waves, RMS = 0.0275 waves, plane: image plane, exit pupil diameter: 4.2642E01 mm, tilt removal: X = 0.0000, Y = 0.0000 waves.

[0047] Figure 12a This is the wavefront diagram at 355nm shortwavelength corresponding to a magnification of 12x in Embodiment 2 of the present invention. In this diagram, 0.3550um is at 0.0000 (degrees), the wavefront to trough ratio is 1.2051, the RMS is 0.1556, the plane is the image plane, the exit pupil diameter is 6.1874E01 mm, and the tilt removal is X = 0.0000 and Y = 0.0000.

[0048] Figure 12b This is the wavefront diagram at 532nm shortwavelength corresponding to a magnification of 12x in Embodiment 2 of the present invention. In this diagram, 0.5320um is at 0.0000 (degrees), the wavefront to trough ratio is 0.8438, the RMS ratio is 0.1637, the plane is the image plane, the exit pupil diameter is 6.1874E01 mm, and the tilt removal ratio is X = 0.0000 and Y = 0.0000.

[0049] Figure 12cThis is the wavefront diagram at 1064nm (shortwavelength) corresponding to a magnification of 12x in Embodiment 2 of the present invention. The wavefront diagram shows 1.0640um at 0.0000 (degrees), peak to trough = 0.8763 waves, RMS = 0.0804 waves, plane: image plane, exit pupil diameter: 6.1874E01 mm, tilt removal: X = 0.0000, Y = 0.0000 waves. Detailed Implementation

[0050] To facilitate understanding and implementation of the present invention by those skilled in the art, the present invention will be further described in detail below with reference to embodiments. It should be understood that the embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0051] Example 1:

[0052] A broadband laser zoom beam expander and collimator optical system, with different zoom structures as follows: Figure 1 , Figure 2 and Figure 3 As shown. The laser incident direction, from left to right, passes sequentially through the first lens G1 with a focal length f1, the second lens G2 with a focal length f2, the third lens G3 with a focal length f3, the fourth lens G4 with a focal length f4, the fifth lens G5 with a focal length f5, the sixth lens G6 with a focal length f6, the seventh lens G7 with a focal length f7, the eighth lens G8 with a focal length f8, the ninth lens G9 with a focal length f9, and the protective window plate G10.

[0053] Among them, the first lens G1, the second lens G2, and the third lens G3 constitute a fixed lens group, and the focal length f of the fixed lens group is... 固 =35mm, the fourth lens G4 and the fifth lens G5 constitute a zoom lens group, the focal length f of the zoom lens group is 35mm. 变 =-15mm, the sixth lens G6, the seventh lens G7, the eighth lens G8, and the ninth lens G9 constitute the compensating lens group, and the focal length f of the compensating lens group is... 补 =375mm.

[0054] The first lens G1 is a meniscus positive lens, the second lens G2 is a biconcave negative lens, and the third lens G3 is a meniscus positive lens. The focal lengths of each lens in the fixed lens group satisfy the same condition as the focal length of the fixed lens group: f1 / f 固 =0.97, f2 / f 固 =-1.53, f3 / f 固 =1.51.

[0055] The fourth lens G4 is a biconcave negative lens, and the fifth lens G5 is a biconvex positive lens. The focal lengths of each lens in the zoom lens group satisfy the following relationship with the focal length of the zoom lens group: f4 / f 变 =0.505, f5 / f补 = -1.77.

[0056] Lens G6 (sixth lens) is a biconcave negative lens, lens G7 (seventh lens) is a biconvex positive lens, lens G8 (eighth lens) is a biconcave negative lens, and lens G9 (ninth lens) is a biconvex positive lens. The focal lengths of each lens in the compensating lens group satisfy: f6 / f 补 =-0.26, f7 / f 补 =0.21, f8 / f 补 =-0.215, f9 / f 补 =0.28.

[0057] Table 1 shows the distances D7 between the fixed lens group and the zoom lens group, and D11 between the zoom lens group and the compensation lens group at different magnifications in Example 1. Table 2 shows the lens structure parameters of Example 1.

[0058] Figure 1 In the middle, along the direction of the light path, from left to right,

[0059] The first lens G1 has a first left lens surface 11 and a first right lens surface 12 on its left and right sides, respectively.

[0060] The second lens G2 has a second left mirror surface 21 and a second right mirror surface 22 on its left and right sides, respectively.

[0061] The left and right sides of the third lens G3 are the third left lens surface 31 and the third right lens surface 32, respectively.

[0062] The fourth lens G4 has a left lens surface 41 and a right lens surface 42 on its left and right sides, respectively.

[0063] The fifth lens G5 has a left lens surface 51 and a right lens surface 52 on its left and right sides, respectively.

[0064] The left and right sides of the sixth lens G6 are the sixth left lens surface 61 and the sixth right lens surface 62, respectively.

[0065] The left and right sides of the seventh lens G7 are the seventh left lens surface 71 and the seventh right lens surface 72, respectively.

[0066] The left and right sides of the eighth lens G8 are the eighth left lens surface 81 and the eighth right lens surface 82, respectively.

[0067] The left and right sides of the ninth lens G9 are the left lens surface 91 and the right lens surface 92, respectively.

[0068] The left and right sides of the protective window plate G10 are the left mirror 101 and the right mirror 102, respectively.

[0069] The numbers 11, 12, 21, 22, 31, 32, 41, 42, 51, 52, 61, 62, 71, 72, 81, 82, 91, 92, 101, and 102 mentioned above are not reference numerals in the attached diagram, but merely indicate the mirror number.

[0070] like Figure 1 The diagram shown is a schematic of the optical structure of the optical system in Example 1 at a magnification of 4x.

[0071] like Figure 2 The diagram shown is a schematic of the optical structure of the optical system in Example 1 at a magnification of 8x.

[0072] like Figure 3 The diagram shown is a schematic of the optical structure of the optical system in Example 1 at a magnification of 12x.

[0073] like Figure 4a , Figure 4b and Figure 4c The image shows the wavefront diagrams of the optical system of Example 1 at a magnification of 4x, at short wavelengths (355nm), intermediate wavelengths (532nm), and long wavelengths (1064nm).

[0074] like Figure 5a , Figure 5b and Figure 5c The image shows the wavefront diagrams of the optical system of Example 1 at a magnification of 8x, at short wavelengths (355nm), intermediate wavelengths (532nm), and long wavelengths (1064nm).

[0075] like Figure 6a , Figure 6b and Figure 6c The image shows the wavefront diagrams of the optical system of Example 1 at a magnification of 12x, at short wavelengths (355nm), intermediate wavelengths (532nm), and long wavelengths (1064nm).

[0076] Throughout all magnification ranges, the root mean square difference of the wavefront pattern ripples across the entire operating band is less than 1 / 4 wavelength, indicating that Example 1 exhibits excellent beam-expanding quality across both the entire magnification range and the entire band.

[0077] Example 2:

[0078] A broadband laser zoom beam expander and collimator optical system, with different zoom structures as follows: Figure 7 , Figure 8 and Figure 9As shown. The laser incident direction, from left to right, passes sequentially through the first lens G1 with a focal length f1, the second lens G2 with a focal length f2, the third lens G3 with a focal length f3, the fourth lens G4 with a focal length f4, the fifth lens G5 with a focal length f5, the sixth lens G6 with a focal length f6, the seventh lens G7 with a focal length f7, the eighth lens G8 with a focal length f8, the ninth lens G9 with a focal length f9, and the protective window plate G10.

[0079] Among them, the first lens G1, the second lens G2, and the third lens G3 constitute a fixed lens group, and the focal length f of the fixed lens group is... 固 =35mm, the fourth lens G4 and the fifth lens G5 constitute a zoom lens group, the focal length f of the zoom lens group is 35mm. 变 =-15mm, the sixth lens G6, the seventh lens G7, the eighth lens G8, and the ninth lens G9 constitute the compensating lens group, and the focal length f of the compensating lens group is... 补 =375mm.

[0080] The first lens G1 is a meniscus positive lens, the second lens G2 is a biconcave negative lens, and the third lens G3 is a meniscus positive lens. The focal lengths of each lens in the fixed lens group satisfy the same condition as the focal length of the fixed lens group: f1 / f 固 =0.877, f2 / f 固 =-1.24, f3 / f 固 =1.44.

[0081] The fourth lens G4 is a biconcave negative lens, and the fifth lens G5 is a biconvex positive lens. The focal lengths of each lens in the zoom lens group satisfy the following relationship with the focal length of the zoom lens group: f4 / f 变 =0.516, f5 / f 补 = -1.77.

[0082] Lens G6 (sixth lens) is a biconcave negative lens, lens G7 (seventh lens) is a biconvex positive lens, lens G8 (eighth lens) is a biconcave negative lens, and lens G9 (ninth lens) is a biconvex positive lens. The focal lengths of each lens in the compensating lens group satisfy: f6 / f 补 =-0.26, f7 / f 补 =0.185, f8 / f 补 =-0.178, f9 / f 补 =0.25.

[0083] Table 3 shows the distance D7 between the fixed lens group and the zoom lens group, and the distance D11 between the zoom lens group and the compensation lens group at different magnifications in Example 2. Table 4 shows the lens structure parameters in Example 1.

[0084] Figure 7 In the middle, along the direction of the light path, from left to right,

[0085] The first lens G1 has a first left lens surface 11 and a first right lens surface 12 on its left and right sides, respectively.

[0086] The second lens G2 has a second left mirror surface 21 and a second right mirror surface 22 on its left and right sides, respectively.

[0087] The left and right sides of the third lens G3 are the third left lens surface 31 and the third right lens surface 32, respectively.

[0088] The fourth lens G4 has a left lens surface 41 and a right lens surface 42 on its left and right sides, respectively.

[0089] The fifth lens G5 has a left lens surface 51 and a right lens surface 52 on its left and right sides, respectively.

[0090] The left and right sides of the sixth lens G6 are the sixth left lens surface 61 and the sixth right lens surface 62, respectively.

[0091] The left and right sides of the seventh lens G7 are the seventh left lens surface 71 and the seventh right lens surface 72, respectively.

[0092] The left and right sides of the eighth lens G8 are the eighth left lens surface 81 and the eighth right lens surface 82, respectively.

[0093] The left and right sides of the ninth lens G9 are the left lens surface 91 and the right lens surface 92, respectively.

[0094] The left and right sides of the protective window plate G10 are the left mirror 101 and the right mirror 102, respectively.

[0095] The numbers 11, 12, 21, 22, 31, 32, 41, 42, 51, 52, 61, 62, 71, 72, 81, 82, 91, 92, 101, and 102 mentioned above are not reference numerals in the attached diagram, but merely indicate the mirror number.

[0096] like Figure 7 The diagram shown is a schematic of the optical structure of the optical system in Example 2 at a magnification of 4x.

[0097] like Figure 8 The diagram shown is a schematic of the optical structure of the optical system in Example 2 at a magnification of 8x.

[0098] like Figure 9 The diagram shown is a schematic of the optical structure of the optical system in Example 2 at a magnification of 12x.

[0099] like Figure 10a , Figure 10b and Figure 10cThe image shows the wavefront diagrams of the optical system of Example 2 at a magnification of 4x, at short wavelength (355nm), intermediate wavelength (532nm), and long wavelength (1064nm).

[0100] like Figure 11a , Figure 11b and Figure 11c The image shows the wavefront diagrams of the optical system of Example 2 at a magnification of 8x, at short wavelengths (355nm), intermediate wavelengths (532nm), and long wavelengths (1064nm).

[0101] like Figure 12a , Figure 12b and Figure 12c The image shows the wavefront diagrams of the optical system of Example 2 at a magnification of 12x, at short wavelengths (355nm), intermediate wavelengths (532nm), and long wavelengths (1064nm).

[0102] Table 1 shows the distance D7 between the fixed lens group and the variable lens group, and the distance D11 between the variable lens group and the compensation lens group at different magnifications in Example 1.

[0103]

[0104] Table 2 shows the lens structure parameters for Example 1.

[0105]

[0106]

[0107] Table 3 shows the distance D7 between the fixed lens group and the variable lens group, and the distance D11 between the variable lens group and the compensation lens group at different magnifications in Example 2.

[0108]

[0109] Table 4 shows the lens structure parameters for Example 2.

[0110]

[0111]

[0112] It should be noted that the specific embodiments described in this invention are merely illustrative of the spirit of the invention. Those skilled in the art to which this invention pertains can make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

Claims

1. A broadband laser variable magnification beam expander and collimator optical system, characterized in that, It includes a fixed lens group coaxially arranged along the direction of light transmission for focusing the light, a zoom lens group for changing the magnification, a compensating lens group for compensating for the movement of the zoom lens group, and a protective window. The optical power of the fixed lens group is positive, the optical power of the zoom lens group is negative, the optical power of the compensating lens group is positive, and the protective window has no optical power. The fixed lens group includes a first lens, a second lens, and a third lens arranged sequentially along the light transmission direction. The optical powers of the first lens, the second lens, and the third lens are positive, negative, and positive, respectively. The zoom lens group includes a fourth lens and a fifth lens arranged sequentially along the light transmission direction, with the fourth lens having negative and the fifth lens having positive optical powers, respectively. The compensation lens group includes a sixth lens, a seventh lens, an eighth lens, and a ninth lens arranged sequentially along the light transmission direction. The optical powers of the sixth lens, the seventh lens, the eighth lens, and the ninth lens are negative, positive, negative, and positive, respectively. The focal lengths of each lens in the fixed lens group are the same as the focal length of the fixed lens group. The ratio between them satisfies the following conditions: , , ,in , , These are the focal lengths of the first lens, the second lens, and the third lens, respectively. To fix the focal length of the lens group, The focal length of each lens in the zoom group is equal to the focal length of the zoom group itself. The ratio between them satisfies the following conditions: , ,in , These are the focal lengths of the fourth and fifth lenses, respectively. The focal length of the zoom lens group. The focal lengths of each lens in the compensation lens group The ratio between them satisfies the following conditions: , , , ,in , , These are the focal lengths of the sixth, seventh, and eighth lenses, respectively. To compensate for the focal length of the lens group.

2. The broadband laser variable magnification beam expander and collimator optical system according to claim 1, characterized in that, The protective window is made of fused silica.

3. The broadband laser variable magnification beam expanding and collimating optical system according to claim 2, characterized in that, The first lens is a meniscus positive lens, the second lens is a biconcave negative lens, the third lens is a meniscus positive lens, the fourth lens is a biconcave negative lens, the fifth lens is a biconvex positive lens, the sixth lens is a biconcave negative lens, the seventh lens is a biconvex positive lens, the eighth lens is a biconcave negative lens, and the ninth lens is a biconvex positive lens.

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