阅读说明：本技术 一种把高斯光束变换为平顶光束的单个非球面透镜 (Single aspheric lens for converting Gaussian beam into flat-topped beam ) 是由 李浩楠 段明 秦华 于 2021-06-28 设计创作，主要内容包括：本发明提供一种把高斯光束变换为平顶光束的单个非球面透镜。该单个非球面透镜前表面为凹非球面,单个非球面透镜后表面为凸非球面,侧表面为圆柱面；单个非球面透镜针对光强分布为I(r)＝I-0exp(-2r～(2)/r-0～(2))的红光光束进行整形,I-0为中心光强,高斯光斑半径r-0＝8mm。本发明适合作为泵浦光,解决中心区域高峰值光强的激光光束很可能破坏晶体介质的问题。(The present invention provides a single aspheric lens that converts a gaussian beam to a flat-topped beam. The front surface of the single aspheric lens is a concave aspheric surface, the rear surface of the single aspheric lens is a convex aspheric surface, and the side surface of the single aspheric lens is a cylindrical surface; a single aspherical lens having an intensity distribution of I (r) ═ I 0 exp(‑2r 2 /r 0 2 ) Shaping the red light beam of (1) 0 Is the central light intensity, Gaussian spot radius r 0 8 mm. The invention is suitable for being used as pump light, and solves the problem that the laser beam with high peak light intensity in the central area is likely to damage the crystal medium.)

1. A single aspheric lens for converting a Gaussian beam into a flat-topped beam is characterized in that the front surface of the single aspheric lens is a concave aspheric surface, the rear surface of the single aspheric lens is a convex aspheric surface, and the side surface of the single aspheric lens is a cylindrical surface; a single aspherical lens has a light intensity distribution ofShaping the red light beam of (1)₀Is the central light intensity, Gaussian spot radius r₀＝8mm；

In rectangular coordinate system xyz, the front and back surfaces of the single aspheric lens are described by the following equation:

wherein, x represents an axial value along the optical axis direction, also called mirror depth, with the intersection point of the front and rear surfaces of a single aspheric lens and the optical axis of the lens as a starting point;is the vertical axis height of the point (y, z) on the aspheric surface, C is the curvature of the aspheric surface vertex, a₂Is the conic constant, a_2jThe aspheric surface deformation coefficient is 2X j order, j is a natural number from 2 to 8, and the X axis is the optical axis of the lens and is also the symmetry axis of a single aspheric lens; the distance between the front surface and the vertex of the back surface of the single aspheric lens is 33.604mm, and the values of other parameters are shown in table 1:

2. the single aspheric lens for converting a gaussian beam into a flat-topped beam as claimed in claim 1, wherein the single aspheric lens is made of SK2 glass with a refractive index of 1.601681 for red light.

3. The single aspheric lens for converting a gaussian beam into a flat-topped beam of claim 1, where the single aspheric lens has a front surface clear aperture of 2 x 8mm and a rear surface clear aperture of 2 x 12 mm.

Technical Field

The invention relates to the technical field of non-imaging optics and laser beam shaping, in particular to a single aspheric lens for converting a Gaussian beam into a flat-topped beam.

Background

In the applications of laser shock processing, laser cleaning, laser holography, laser medical treatment, laser ranging, radar and the like, the action light beam is expected to be a flat-top light beam with uniformly distributed light intensity in the cross section, but most of the light beams emitted by the laser are Gaussian light beams with non-uniformly distributed light intensity. The main means for converting Gaussian beams into flat-topped beams is to rely on a set of shaping systems, and the shaping systems mainly comprise an optical filter shaping system with inverse Gaussian distribution absorption, a birefringence index lens group shaping system, a micro lens array shaping system, a diffractive optical element shaping system, a liquid crystal spatial light modulator shaping system, a holographic filter shaping system, an amplitude modulation grating shaping system and an aspheric lens group shaping system.

Among the shaping systems, the aspheric lens shaping system has the advantages of simple structure, high shaping efficiency, high damage threshold, easiness in implementation and the like, and has important engineering application value. The aspherical lens shaping system may have only a single lens or may be composed of two or more lenses. Yamamota designs a shaping lens that shapes an elliptical beam generated by a semiconductor laser into a circular, axisymmetric beam for application to a laser printer. A double-piece aspheric lens shaping system is designed by Banton and Harrigan to convert a laser beam with Gaussian distribution of light intensity into a round flat-top beam with slightly stronger light intensity at the edge of the beam. The first lens redistributes the energy of the passing light beam to change the light intensity distribution of the light beam, and the second lens redirects the light beam to exit in parallel. Because one surface of each lens of the double-lens aspheric lens system is a plane, the double-lens aspheric lens can be simplified into one lens, the front surface and the rear surface of the lens are aspheric surfaces, and the two lenses in the double-lens system are respectively replaced to realize homogenization and collimation of light beams.

The single lens is simple to assemble and convenient to use, and can achieve the same effect of a plurality of lenses.

Disclosure of Invention

The invention aims to provide a single aspheric lens for converting a Gaussian beam into a flat-topped beam, which relates to the problems of beam expansion and collimation with larger multiplying power.

The invention provides a single aspheric lens for converting a Gaussian beam into a flat-topped beam, wherein the front surface of the single aspheric lens is a concave aspheric surface, the rear surface of the single aspheric lens is a convex aspheric surface, and the side surface of the single aspheric lens is a cylindrical surface; a single aspherical lens has a light intensity distribution ofShaping the red light beam of (1)₀Is the central light intensity, Gaussian spot radius r₀＝8mm；

In rectangular coordinate system xyz, the front and back surfaces of the single aspheric lens are described by the following equation:

wherein, x represents an axial value along the optical axis direction, also called mirror depth, with the intersection point of the front and rear surfaces of a single aspheric lens and the optical axis of the lens as a starting point;is the vertical axis height of the point (y, z) on the aspheric surface, C is the curvature of the aspheric surface vertex, a₂Is the conic constant, a_2jThe aspheric surface deformation coefficient is 2X j order, j is a natural number from 2 to 8, and the X axis is the optical axis of the lens and is also the symmetry axis of a single aspheric lens; the distance between the front surface and the vertex of the back surface of the single aspheric lens is 33.604mm, and the values of other parameters are shown in table 1:

further, the material used for the single aspheric lens is SK2 glass with 1.601681 refractive index for red light.

Further, the aperture of the front surface light passing through the single aspherical lens is 2 × 8mm, and the aperture of the rear surface light passing through the single aspherical lens is 2 × 12 mm.

The invention has the beneficial effects that:

the single aspheric lens for converting the Gaussian beam into the flat-top beam has the advantages that the front surface and the rear surface of the lens are both aspheric surfaces, so that the good light transmission performance is ensured, the lens can convert the light beam with the Gaussian distribution of the light intensity into the flat-top beam with the uniformly distributed light intensity, the output light intensity is the inverse Gaussian distribution with a slightly concave center, the lens is suitable for being used as pump light, and the problem that the laser beam with the high peak light intensity in the central area possibly damages a crystal medium is solved.

Drawings

FIG. 1 is a schematic diagram of a single aspheric lens for converting a Gaussian beam to a flat-topped beam according to an embodiment of the present invention;

FIG. 2 is a two-dimensional optical path simulation diagram of a Gaussian beam transformed into a flat-topped beam by a single aspheric lens according to an embodiment of the present invention;

FIG. 3 is a three-dimensional optical path simulation diagram of transforming a Gaussian beam into a flattened beam by a single aspheric lens according to an embodiment of the present invention;

FIG. 4 is a simulation diagram of a one-dimensional light intensity distribution of a single aspheric lens on a light beam output surface thereof according to an embodiment of the present invention

FIG. 5 is a three-dimensional light intensity distribution simulation diagram of a single aspheric lens at the light output surface thereof according to an embodiment of the present invention;

description of the drawings: 1 is the front surface of a single aspheric lens, 2 is the back surface of a single aspheric lens, 3 is the incident beam, and 4 is the outgoing beam.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly described below with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

As shown in fig. 1, the embodiment of the present invention provides a single aspheric lens for converting a gaussian beam into a flat-topped beam, wherein the front surface 1 of the single aspheric lens is a concave aspheric surface, the rear surface 2 of the single aspheric lens is a convex aspheric surface, and the side surface is a cylindrical surface; a single aspherical lens has a light intensity distribution ofShaping the red light beam of (1)₀Is the central light intensity, Gaussian spot radius r₀8 mm; irradiation intensity of the outgoing beam

In rectangular coordinate system xyz, the front and back surfaces of the single aspheric lens are described by the following equation:

wherein, x represents an axial value along the optical axis direction, also called mirror depth, with the intersection point of the front and rear surfaces of a single aspheric lens and the optical axis of the lens as a starting point;is the vertical axis height of the point (y, z) on the aspheric surface, C is the curvature of the aspheric surface vertex, a₂Is the conic constant, a_2jThe aspheric surface deformation coefficient is 2 x j order, j is a natural number from 2 to 8, and the x axis is the optical axis of the lens and is also the symmetry axis of a single aspheric lens; the distance d between the front surface and the vertex of the back surface of the single aspheric lens is 33.604mm, and the values of other parameters are shown in table 1.

The single aspheric lens in the embodiment of the invention adopts optical glass, preferably SK2 glass with 1.601681 refractive index for red light. The aperture of the front surface of the single aspheric lens is 2 x 8mm, and the aperture of the rear surface of the single aspheric lens is 2 x 12 mm. The side surface of the single aspherical lens is a cylindrical surface with a bottom surface radius of 12.5 mm.

Fig. 2 is a two-dimensional optical path simulation diagram of a single aspheric Lens for converting a gaussian beam into a flat-topped beam, which is obtained by substituting relevant parameters of the Lens into corresponding positions of Lens Data Editor in zemax software. As shown in fig. 2, the directions from the incident beam 3 to the emergent beam 4 are a single aspheric lens front surface 1 and a single aspheric lens back surface 2, respectively. From this figure it can be seen that: the front surface 1 of the single aspheric lens is a light input surface, is a concave aspheric surface and is concave to the light beam output direction; the single aspheric lens rear surface 2 is a light output surface, is a convex aspheric surface and is convex to a light beam output direction; the front and rear surfaces of the single aspherical lens are each in a shape symmetrical with the optical axis X. In the embodiment of the invention, the incident beam 3 is a Gaussian beam, and the emergent beam 4 is a converted flat-top beam.

The density of the light rays in fig. 2 represents the intensity of the light, and it can be seen from fig. 2 that the incident light beam with high central light density becomes a flat-top light beam with uniform light distribution on the section of the emergent light beam after passing through the single aspheric lens. In fig. 2 the incident beam 3 has a radius of 8mm and the emergent beam 4 has a radius of 12 mm.

As shown in fig. 3, the three-dimensional optical path diagram is obtained by writing matlab program simulation, in which a single aspheric lens of the present invention converts a gaussian beam with an incident spot radius of 8mm into a flat-top beam with an emergent beam radius of 12 mm. The complete shape of the aspherical lens of the invention can be seen more intuitively in fig. 3.

As shown in fig. 4, the two-dimensional light intensity distribution simulation diagram of a single aspheric Lens of the present invention on the light beam output surface is obtained by substituting the relevant parameters of the Lens of the present invention into the corresponding position of Lens Data Editor in zemax software and outputting through Illumination, and the light intensity distribution curve is relatively smooth, which proves that the input gaussian beam is indeed converted into the flat-top light beam with uniformly distributed light intensity on the output light beam section.

Fig. 5 is a three-dimensional light intensity distribution simulation diagram of a single aspheric lens of the present invention on its light beam output surface, which is obtained by writing matlab program to trace 32969025 ten thousand light rays, where RI is an abbreviation of relative illuminance. It can be seen more clearly from fig. 5 that the output light spot shape is consistent with the shape of a flat-top hat, demonstrating that the gaussian beam has indeed been converted into a flat-top beam. As can be seen from the coordinate axes in fig. 5, the radius of the output spot is 12 mm.

Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.