Laser shaping design method based on single-lens type integral lens

Abstract

The invention discloses a laser shaping design method for a single-lens type integral lens, and belongs to the technical field of laser shaping. The system is composed of a single reflection type integral mirror curved surface, the curved surface is formed by horizontally stretching a specially-designed mirror surface bus, and a point Gaussian light source can be directly shaped into two special light spots: one is a fan-shaped light spot with strong energy in the middle and weak energy on two sides; and the intensity of the two sides of the rectangular M-shaped light spot can be dynamically adjusted along with the distance between the light source and the mirror surface. Compared with a traditional integral mirror scheme, a collimating mirror is omitted, the system structure is remarkably simplified, the stability is improved, and the optical loss is reduced; meanwhile, due to the characteristic that the light spot energy distribution is adjustable, the application range of the method in laser application is effectively expanded.

Description

Technical Field

[0001] This design belongs to the field of laser cosmetic surgery, and specifically relates to a laser cosmetic surgery design method based on a single-mirror integrating mirror. Background Technology

[0002] In traditional laser reshaping systems, an integrating mirror system composed of multiple sub-mirrors is often used to achieve uniform rectangular or linear (fan-shaped) beams. This type of system typically requires first using a collimating mirror to convert the diverging point source into parallel light, and then using an integrating mirror to split and superimpose the beam to achieve optical field homogenization. However, this approach suffers from complex optical structures and a large number of components, leading to difficult system assembly and adjustment, poor mechanical stability, and high transmission losses introduced by the multi-stage optical interfaces, thus reducing overall light energy utilization.

[0003] To address the urgent need for flexible control of laser spot morphology in laser processing applications, especially in the design of novel optical surfaces, there is a pressing need to develop an innovative solution that can directly shape a point light source into a target laser spot using a single mirror. This design must be able to controllably adjust the energy distribution of the laser spot at different light source-mirror distances. Specifically, it must maintain a uniform energy distribution in the y-direction while allowing a continuous transition from a single-peak morphology to a bi-peak (M-type) distribution in the x-direction as the distance changes, thereby significantly improving the adaptability and energy utilization efficiency of the laser spot in dynamic processing. Summary of the Invention

[0004] The purpose of this invention is to provide a single-mirror laser shaping integrator with adjustable spot energy. By adjusting the distance between the point light source and the mirror, the spot energy distribution on the working surface is changed. As the distance between the point light source and the mirror changes, the spot energy on the working surface gradually changes from a single peak to a double peak distribution in the x-direction, and forms a standard M-shaped spot distribution at a certain distance, while the y-direction always maintains a uniform energy distribution.

[0005] Technical Method of the Invention The single-mirror integrating mirror is a single curved surface formed by stretching a generatrix. It can form a fan-shaped light spot with strong energy in the middle and weak energy on both sides at a specific working distance from a point light source. The highest light intensity in the x-direction can vary with the distance between the point light source and the mirror surface. When the distance between the point light source and the mirror surface reaches a certain value, it can form an M-shaped light spot with equal left and right peaks. At the same time, the energy in the y-direction remains uniform. The aforementioned busbar design method defines its curve in the xoz plane as a sixth-order polynomial: , The x range is from -66 to -28.0592255 mm.

[0006] The lens barrel is 32mm long, the point light source wavelength is 635nm, the divergence angle is 30 degrees, the working distance between the point light source and the mirror is in the range of 45mm to 90mm, the distance between the mirror and the working surface is 400mm, and the size of the system components can be adjusted according to the required spot size. Attached Figure Description

[0007] Figure 1 Schematic diagram of a mirror bus design; Figure 2 This is a schematic diagram showing the tilt and angle between the light rays and the mirror surface. Figure 3 This is a graph showing the effect of the polynomial degree on the fitting accuracy. Figure 4 The curve is a fitting curve of the sixth-order polynomial of the mirror line. Figure 5 This is a diagram of a single-mirror integrating mirror model. Figure 6 A two-dimensional graph of the intensity of a point light source; Figure 7 Structure of laser shaping system and various output spot patterns Figure 8 The output light spot contour diagrams are shown for the following shapes at different distances between the mirror and the point light source: fan-shaped (a), right-strong M-shaped rectangle (b), standard M-shaped rectangle (c), and left-strong M-shaped rectangle (d). Figure 9 Intensity diagrams of the output light spot in the x-direction for fan-shaped (a), right-strong M-shaped rectangle (b), standard M-shaped rectangle (c), and left-strong M-shaped rectangle (d). Figure 10 Intensity diagrams of the output light spot along the y-direction for fan-shaped (a), right-strong M-shaped rectangle (b), standard M-shaped rectangle (c), and left-strong M-shaped rectangle (d). Detailed Implementation

[0008] like Figure 1 As shown, based on the coordinates of the initial point on the mirror generatrix and the input and output positions of the laser beam, the positions of the remaining points along the generatrix can be determined using the law of reflection. The detailed calculation method is as follows: Let P2 be the next point to be determined on the generatrix of the mirror plane. The distance between any two adjacent points along the y-axis is a fixed value h. Given the initial coordinates of P1(x1, y1), the goal is to find the coordinates of the next point P2(x2, y2). The slope of line segment P1P2 is given by the following formula: (1) Since the distance h between any two points is taken to be very small, the slope k1 of line segment P1P2 can be approximated as the slope of the tangent at point P2.

[0009] After reflection at point P2, beam segment S-P2 is guided towards the target point T on the beam spot. Therefore, the analytical equations for line segments S-P2 and P2-T can be expressed as follows: (2) (3) Similarly, the analytical equation for line P2-T is given by the following equation: (4) (5) like Figure 2 As shown, in the design, the mirror curves are distributed along the y-axis, and their slope is denoted as k1. Therefore, the slope of the tangent at point P2 is defined as k1. Let the slope of ray S-P2 be k2, and the slope of ray P2-T be k3. Therefore, we can obtain: (6) (7) (8) (9) According to the formula for the angle between two vectors in two dimensions: (10) Therefore, the sine of the angle between the ray and the tangent at point P2 can be expressed as: (11) (12) According to the law of reflection, sin(θ1) = sin(θ2), therefore: (13) Given the coordinates of an initial point P1 and a predefined interval h between points P2 along the y-direction, the coordinates of P2 can be obtained by substituting them into the above equation and selecting an appropriate solution from the possible roots. Following this logic, the coordinates of the mirror points can be calculated point by point. Similarly, to calculate the generated line points from the initial point in the opposite direction, a negative y-direction interval can be set and the same method applied. In this way, all points along the mirror generated line can be calculated completely.

[0010] To achieve a uniform energy distribution perpendicular to the forming direction, we stretched the designed mirror profile to obtain an integral mirror based on geometric principles. Simultaneously, to ensure that the light intensity on the working surface varies with the distance between the mirror and the point light source, we designed the light rays to be reflected back and forth onto the working surface in a regular pattern. As the energy reflected by the mirror changes, the energy of the light spot on the working surface also changes accordingly.

[0011] Fitting of mirror generatrix according to Figure 3 The coefficient of determination R² is used to input the mirror data into MATLAB for sixth-order polynomial fitting, resulting in the following equation for the mirror generatrix: , The corresponding fitted curve Figure 4 As shown.

[0012] The mirror surface was modeled using SolidWorks. A mirror curve was generated by opening the sketch in SolidWorks and inputting the fitted mirror function into the equation-driven curve properties. This curve was then stretched over the mirror surface. To ensure the output light spot was rectangular, the mirror surface needed to be clipped to obtain the final mirror model. The resulting model... Figure 5 .

[0013] Input light spot such as Figure 6 As shown, the point light source is a Gaussian-like circular light spot. Figure 7 This describes the structure of the laser shaping system and various output spot patterns. Based on... Figure 8 , Figure 9 , Figure 10 The output light spot contour diagram, x-direction light intensity diagram, and y-direction light intensity diagram at different distances between the mirror and the point light source show that the output light spot on the working surface gradually changes from a single-peak light spot with high energy in the middle and low energy around the edges to a double-peak light spot of M-shape under different distances between the mirror and the point light source. As the distance increases, the highest energy peak shifts from right to left and forms a standard M-shaped light spot at a certain distance. The light intensity energy in the y-direction remains uniform.

Claims

1. A laser beam shaping method based on a single-mirror integrator, characterized in that The method comprises the following steps: A point light source is provided, which has a wavelength of 635 nm and a divergence angle of 30 degrees; a single-mirror integrating mirror is provided, the integrating mirror is formed by stretching a preset mirror generatrix along a one-dimensional direction to form a continuous optical curved surface; the point light source is placed in an object space of the integrating mirror, and the distance between the point light source and the integrating mirror is adjustable, and the adjustment range is 45 mm to 100 mm; the integrating mirror reflects and shapes the divergent light beam emitted by the point light source, and forms an illumination light spot on a target surface 400 mm away from the integrating mirror in an image space; wherein the mirror generatrix is located in an XOZ plane, and the curve of the mirror generatrix is defined by a six-order polynomial function: ， wherein the x coordinate ranges from -66 to -28.0592255 mm; The curved surface formed by stretching the generatrix along the Y direction makes the illumination light spot have uniform energy distribution in the Y direction, and can form two light intensity distribution patterns in the X direction: when the point light source is at a specific working distance, a fan-shaped light spot with high central energy and low energy on both sides is formed; when the distance between the point light source and the integrating mirror changes, an M-shaped light spot is formed, in which the position of the energy peak in the X direction changes with the distance.

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