A vortex beam generation device, system and method with adjustable topological number

Abstract

The invention discloses a vortex beam generation device, system and method with an adjustable topological number. The vortex beam generation device with an adjustable topological number includes two helical phase mirrors, and the phases of the two helical phase mirrors are respectively set is Aθ 2 and ‑Aθ 2 , two helical phase mirrors are arranged on the optical path in turn, and the topological number of the vortex beam obtained by increasing the angle difference between the two helical phase mirrors increases by 1. After the laser beam is located in this device, it can be added with a helical phase factor to achieve phase modulation, so that the energy distribution of the laser beam becomes a circular distribution, and the angle difference between the two helical phase mirrors can be controlled by rotating one or two helical phase mirrors. The topological number of the resulting vortex beam is tuned, resulting in a ring-shaped spot with tunable size. In the present invention, a group of spiral phase mirrors with a second-order nonlinear spiral structure are designed to superimpose and generate a vortex beam with an adjustable topological number, forming an annular spot with energy distribution concentrated on the edge, a larger diameter, a longer focal depth, and an adjustable size. .

Description

technical field [0001] The invention belongs to the field of laser applications, and more specifically, the invention relates to a vortex beam generation device, system and method with adjustable topology number. Background technique [0002] The energy distribution of ordinary Gaussian beams decreases from the center to the edge, and most of the energy is concentrated in the central area. In the field of laser processing, especially in the fields of laser welding, cutting, cladding, etc., ablation and other phenomena may occur if the center energy is too high, and due to insufficient energy at the edge, when performing deep processing such as laser cutting, the deeper the processing depth, the edge The energy is even more insufficient, which leads to uneven cutting section, which significantly limits the processing quality and processing accuracy. [0003] In view of the above problems, the commonly used treatment method is to change the Gaussian distribution of light spot...

AI Technical Summary

Problems solved by technology

Due to the high price of the phase plate, more phase plates are needed to realize the flexible and adjustable vortex optical topology number. This method is too expensive and not flexible enough.

2. Based on the axicon lens to generate a combined ring-shaped spot, but due to the limitations of the axicon lens material and processing technology, the range of taper that can be processed is limited at present. When the taper is too small, there will be a large error, and for crystal materials, more It is very difficult to process the mirror surface composed of different taper surfaces, so the ring-shaped light spot output by the transmission type axicon prism has a relatively small adjustable range in terms of ring radius and other parameters, and it is difficult to output multiple ring-shaped combined light spots. Larger, unable to flexibly meet different processing requirements. In addition, the material of the axicon mirror also affects the size of the optical power that can be tolerated; 3. Based on the computational holography method to generate a combined annular spot, the computational holography can in principle be designed to produce a composite annular spot Any spot including the spot, but because the computational holography needs to be completed by a spatial light modulator, the spatial light modulator generally uses off-axis first-order diffracted light, coupled with loss and other factors, so the utilization rate of light energy is low, and It cannot withstand kilowatt-level lasers, so it is relatively less used; 4. The laser with adjustable spot mode based on optical fiber is used to generate combined annular spot. This method realizes the difficulty and cost of adjusting the spot distribution mode in the optical fiber. , because there is no adjustable external optical path, it lacks in flexibility and convenience of use

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