A zoom collimating lens for wavefront correction of fiber-optic output laser

Abstract

The present invention discloses a zoom collimating lens for wavefront correction of optical fiber output laser, which relates to the technical field of collimating lenses. The zoom collimating lens comprises a collimating lens group and a zoom lens group, the collimating lens group comprises a first positive power lens and a first negative power lens, the zoom lens group comprises a second negative power lens, a second positive power lens and a third positive power lens, the positions of the first positive power lens, the first negative power lens and the second negative power lens are fixed, and the second positive power lens and the third positive power lens can be translated along the optical axis direction to achieve optical zoom. The present invention realizes wavefront correction by optimizing the wavefront of a specific wavelength in optical design, obtains relatively ideal collimated light, and adopts a zoom design to change the spot size or light intensity to meet the needs of different test scenarios.

Description

Technical Field

[0001] The invention relates to the technical field of collimating lenses, and in particular to a zoom collimating lens for wavefront correction of optical fiber output laser. Background Art

[0002] In the field of high-energy solid-state lasers, in order to facilitate the testing of the beam quality of high-power laser power amplifier modules, the collimated beam of the semiconductor laser output by fiber coupling is usually used as the measurement light to monitor the wavefront and far-field spot of the beam after transmission through the power amplifier module. The collimating lens used is generally a telescope objective lens, which has the advantages of high technical maturity and low cost. However, due to its imaging application, it is usually necessary to take into account the aberration optimization of the entire visible light band, the spectrum is wide, and the wavefront correction will not be performed for a specific wavelength, resulting in the collimated beam wavefront being not ideal, and there is a wavefront error, which affects the laser power amplifier module beam quality test. In addition, different test scenarios have different requirements for the aperture and light intensity of the collimated beam. The fixed-focus collimating lens is difficult to match the complex test scenarios, and different collimating lenses need to be replaced, which reduces the test efficiency and quality. Therefore, it is necessary to provide a solution for a zoom collimating lens for wavefront correction of fiber-optic output lasers to obtain a more ideal collimated light that can change the beam aperture, and solve the error and efficiency problems of the existing technical solutions in practical applications. Summary of the invention

[0003] The object of the present invention is to provide a zoom collimating lens for wavefront correction of optical fiber output laser in order to solve the above-mentioned problem.

[0004] The present invention achieves the above-mentioned purpose through the following technical solutions:

[0005] A zoom collimator lens for wavefront correction of optical fiber output laser, the zoom collimator lens is used to optimize the wavefront of laser with a central wavelength of 632nm, the zoom collimator lens is used for optical fiber coupling output laser, and the numerical aperture NA of the optical fiber is 0.22, the zoom collimator lens comprises a collimator lens group and a zoom lens group, the collimator lens group comprises a first positive focal power lens and a first negative focal power lens, the zoom lens group comprises a second negative focal power lens, a second positive focal power lens and a third positive focal power lens, the first positive focal power lens, the first negative focal power lens, the second negative focal power lens, the second positive focal power lens and the third positive focal power lens are arranged in sequence along the laser transmission direction.

[0006] Preferably, the first positive power lens is an aspherical lens, and the first negative power lens, the second negative power lens, the second positive power lens and the third positive power lens are all spherical lenses.

[0007] Preferably, the light incident surface of the first positive power lens is an aspherical surface, and the light exit surface of the first positive power lens is a spherical surface.

[0008] Preferably, the light exit surface of the first positive power lens and the light entrance surface of the first negative power lens have the same curvature and complementary concave and convex shapes, and the light exit surface of the first positive power lens and the light entrance surface of the first negative power lens are glued together by optical glue.

[0009] Preferably, the aspheric surface of the first positive power lens satisfies the aspheric surface equation:

[0010]

[0011] Among them, z is the vector height, R is the radius of curvature, k is the cone coefficient, A, B, C, D are the 4th, 6th, 8th, and 10th aspheric coefficients respectively, and r is the annulus radius.

[0012] Preferably, the positions of the first positive power lens, the first negative power lens and the second negative power lens are fixed, and the second positive power lens and the third positive power lens can be translated along the optical axis to achieve optical zoom.

[0013] Preferably, the light is collimated after passing through the collimating lens group; the aperture of the emitted light beam is changed after the light passes through the zoom lens group, and the light is still collimated after passing through the zoom lens group.

[0014] Preferably, the zoom collimator lens is a discontinuous zoom lens, and the zoom collimator lens includes a short focus mode and a long focus mode. The system focal length of the short focus mode is 133 mm, and the output beam diameter is 60 mm; the system focal length of the long focus mode is 332.5 mm, and the output beam diameter is 150 mm.

[0015] Preferably, the relationship between the system focal length f1 of the short-focus mode and the system focal length f2 of the long-focus mode is: f2 / f1=2.5.

[0016] The beneficial effects of the present invention are as follows: (1) The present invention is used for wavefront correction of a specific wavelength, optimizes the wavefront of collimated light, and reduces the interference of the wavefront difference of the collimated light itself on the test results. (2) The zoom system design is adopted to achieve different magnifications of collimated light to change its spot size or light intensity to adapt to different test scenarios and improve the test quality and efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the overall optical structure of the present invention;

[0018] Figure 2 is a schematic diagram of a collimating lens assembly of the present invention;

[0019] Figure 3 is a zoom schematic diagram of the present invention;

[0020] Figure 4 It is the Zemax simulation wavefront diagram of the present invention;

[0021] Figure 5 It is the Zemax simulation modulation transfer function diagram of the present invention.

[0022] Description of reference numerals:

[0023] 1. A first positive power lens; 2. A first negative power lens; 3. A second negative power lens; 4. A second positive power lens; 5. A third positive power lens. DETAILED DESCRIPTION

[0024] The present invention will be further described below in conjunction with the accompanying drawings:

[0025] like Figure 1 As shown, the present invention provides a zoom collimator lens for wavefront correction of optical fiber output laser, the zoom collimator lens is used to optimize the wavefront of laser with a central wavelength of 632nm, the zoom collimator lens is used for optical fiber coupling output laser, and the numerical aperture NA of the optical fiber is 0.22. The zoom collimator lens includes a collimator lens group and a zoom lens group, the collimator lens group includes a first positive focal power lens 1 and a first negative focal power lens 2, and the zoom lens group includes a second negative focal power lens 3, a second positive focal power lens 4, and a third positive focal power lens 5. The first positive focal power lens 1, the first negative focal power lens 2, the second negative focal power lens 3, the second positive focal power lens 4, and the third positive focal power lens 5 are arranged in sequence along the laser transmission direction. After passing through the collimator lens group, the light is collimated light; after passing through the zoom lens group, the light changes the aperture of the emitted light beam, and the light is still collimated light after passing through the zoom lens group. During specific operation, the laser output by the optical fiber passes through the first positive power lens 1, the first negative power lens 2, the second negative power lens 3, the second positive power lens 4 and the third positive power lens 5 in sequence to shape the divergent light beam into collimated light (or parallel light).

[0026] like Figure 1 and Figure 2As shown, on the basis of the above embodiments, further, the first positive power lens 1 is an aspherical lens. The first negative power lens 2, the second negative power lens 3, the second positive power lens 4 and the third positive power lens 5 are all spherical lenses. Among them, the light incident surface of the first positive power lens 1 is an aspherical surface, and the light exit surface of the first positive power lens 1 is a spherical surface. The light exit surface of the first positive power lens 1 has the same curvature as the light incident surface of the first negative power lens 2, and the concave and convex surfaces are complementary. The light exit surface of the first positive power lens 1 and the light incident surface of the first negative power lens 2 are glued by optical glue. Among them, the aspherical surface of the first positive power lens 1 satisfies the aspherical surface equation:

[0027]

[0028] Among them, z is the vector height, R is the radius of curvature, k is the cone coefficient, A, B, C, D are the 4th, 6th, 8th, and 10th aspheric coefficients respectively, and r is the annulus radius.

[0029] The optical system design data of this embodiment is shown in Table 1 below:

[0030] Table 1

[0031]

[0032]

[0033] Among them, the surface type of serial number 1 in Table 1 is an even-order aspheric surface, and the surface parameters are shown in Table 2 below:

[0034] Table 2

[0035] k A B C D 0 -5.892E-5 -6.463E-7 3.197E-8 -5.983E-10

[0036] For example, the first positive power lens 1 can select the surface type of number 1 in Table 1 as an even-order aspheric surface.

[0037] In this embodiment, the focal length of the first positive power lens 1 is 10.907 mm, the focal length of the first negative power lens 2 is -20.391 mm, the focal length of the second negative power lens 3 is -23.688 mm, the focal length of the second positive power lens 4 is 155.332 mm, and the focal length of the third positive power lens 5 is 741.933 mm.

[0038] On the basis of the above embodiment, further, the positions of the first positive power lens 1, the first negative power lens 2 and the second negative power lens 3 are fixed. The second positive power lens 4 and the third positive power lens 5 can be translated along the optical axis to achieve optical zoom. Figure 3As shown, the zoom collimator lens is a non-continuous zoom, and the zoom collimator lens includes a short focus mode and a long focus mode. The system focal length of the short focus mode is 133mm, and the output beam diameter is 60mm; the system focal length of the long focus mode is 332.5mm, and the output beam diameter is 150mm. Among them, the relationship between the system focal length f1 of the short focus mode and the system focal length f2 of the long focus mode is: f2 / f1=2.5.

[0039] In this embodiment, in the short focus mode and the long focus mode, the design positions of the second positive power lens 4 and the third positive power lens 5 are shown in Table 3 below:

[0040] Table 3

[0041] thickness Short Throw Telephoto Surface 5 79.041 36.415 Surface 7 40.761 550

[0042] Table 3 shows the distances between the second positive power lens 4 and the third positive power lens 5 and their adjacent lenses in the short focus mode and the long focus mode, respectively. The distance is expressed as the center distance between adjacent surfaces of the lens, which is called thickness in the ZEMAX software. Table 3 is derived from the ZEMAX software. The specific meaning of the data in Table 3 is that in the short focus mode, the thickness (center distance) between the surface 5 and the next surface is 79.041 mm, and the thickness (center distance) between the surface 7 and the next surface is 40.761 mm; in the long focus mode, the thickness (center distance) between the surface 5 and the next surface is 36.415 mm, and the thickness (center distance) between the surface 7 and the next surface is 550 mm.

[0043] The collimating lens group and the zoom lens group of this embodiment are optimized for the wavefront of a specific wavelength during the optical design, and the size, curvature, material and spacing of each lens are strictly matched according to the optical design scheme.

[0044] like Figure 4 As shown in the figure, the Zemax simulated wavefront diagram of the zoom collimator lens for wavefront correction of the optical fiber output laser of this embodiment. After the wavefront of the optical fiber output laser passes through the actual optical system, the optical path difference between the actual wavefront and the ideal wavefront is the wave aberration. If the wave aberration is less than λ / 4 wavelength, the imaging quality of the optical system is ideal. In this embodiment, the wave aberration PV value is 0.0487λ for short focus and 0.0821λ for long focus, and the RMS value is 0.0114λ for short focus and 0.028λ for long focus, λ=632nm, and the wavefront quality is good.

[0045] like Figure 5 As shown in FIG. 1 , the Zemax simulation modulation transfer function diagram of the zoom collimator lens for wavefront correction of fiber-optic output laser of this embodiment. The modulation transfer function (MTF), also known as the spatial frequency contrast sensitivity function, reflects the ability of the optical system to transmit the target light details as a function of spatial frequency. Figure 5It can be seen that the modulation transfer function curve of the system is close to the diffraction limit curve and the image quality is good.

[0046] The present invention realizes wavefront correction by optimizing the wavefront of a specific wavelength in optical design to obtain relatively ideal collimated light, and adopts a zoom design to change the spot size or light intensity to meet the needs of different test scenarios.

[0047] Those skilled in the art should understand that, without departing from the technical solution claimed in the present invention, the number of lenses constituting the lens can be changed to obtain the various results and advantages described in this specification.

[0048] The above are only preferred embodiments of the present invention, and the scope of the present invention is not limited thereby. It should be understood by those skilled in the art that various changes, modifications, substitutions and deformations may be made to these embodiments without departing from the principles and purposes of the present invention, and all of them should be included in the protection scope of the present invention. The protection scope of the present invention is defined by the claims and their equivalents.

Claims

1. A zoom collimating lens for wavefront correction of optical fiber output laser, characterized in that: The zoom collimating lens is used to optimize the wavefront of a laser with a central wavelength of 632nm. The zoom collimating lens is used for optical fiber coupling output laser and the numerical aperture NA of the optical fiber is 0.

22. The zoom collimating lens comprises a collimating lens group and a zoom lens group. The collimating lens group comprises a first positive power lens and a first negative power lens. The zoom lens group comprises a second negative power lens, a second positive power lens and a third positive power lens. The first positive power lens, the first negative power lens, the second negative power lens, the second positive power lens and the third positive power lens are arranged in sequence along the laser transmission direction; the first positive power lens is an aspherical lens, and the first negative power lens, the second negative power lens, the second positive power lens and the third positive power lens are all spherical lenses; the light incident surface of the first positive power lens is an aspherical surface, and the light exit surface of the first positive power lens is a spherical surface.

2. The zoom collimating lens for wavefront correction of optical fiber output laser according to claim 1, characterized in that: The light-emitting surface of the first positive-power lens and the light-entering surface of the first negative-power lens have the same curvature and are complementary in concave and convex directions. The light-emitting surface of the first positive-power lens and the light-entering surface of the first negative-power lens are glued together by optical glue.

3. The zoom collimating lens for wavefront correction of optical fiber output laser according to claim 1, characterized in that: The aspheric surface of the first positive power lens satisfies the aspheric surface equation: Among them, z is the vector height, R is the radius of curvature, k is the cone coefficient, A, B, C, D are the 4th, 6th, 8th, and 10th aspheric coefficients respectively, and r is the annulus radius.

4. The zoom collimating lens for wavefront correction of optical fiber output laser according to claim 1, characterized in that: The positions of the first positive power lens, the first negative power lens and the second negative power lens are fixed, and the second positive power lens and the third positive power lens can be translated along the optical axis to achieve optical zoom.

5. The zoom collimating lens for wavefront correction of optical fiber output laser according to claim 1, characterized in that: After passing through the collimating lens group, the light becomes collimated light; after passing through the zoom lens group, the aperture of the emitted light beam is changed, and the light still becomes collimated light after passing through the zoom lens group.

6. The zoom collimating lens for wavefront correction of optical fiber output laser according to claim 1, characterized in that: The zoom collimator lens is a discontinuous zoom lens and includes a short focus mode and a long focus mode. The system focal length of the short focus mode is 133 mm, and the output beam diameter is 60 mm; the system focal length of the long focus mode is 332.5 mm, and the output beam diameter is 150 mm.

7. The zoom collimating lens for wavefront correction of optical fiber output laser according to claim 6, characterized in that: The relationship between the system focal length f1 of the short-focus mode and the system focal length f2 of the long-focus mode is: f2 / f1=2.5.

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