Development Of An Electric Beam Expander With Controllable Spot Size For Laser 3D Printing

Laser 3D printing technology belongs to the category of laser processing technology and has a wide range of uses.However,unlike ordinary two-dimensional laser processing technology,the spot size on the processing plane often needs to be changed according to the laser scanning position(such as Double the diameter of the fine spot of 20 μm to 40 μm to increase the scanning processing efficiency).Although the dynamic focusing unit commonly used for laser 3D printing can continuously change the spot diameter of the working surface,its control method is complex,the purchase price is high,and it generally needs to be used in conjunction with a beam expander,occupying a large amount of system internal space and cost.The purpose of this paper is to develop a modular unit for controlling the spot diameter of the working surface suitable for laser 3D printing.This thesis starts with the study of dynamic focusing technology.It is envisaged to combine a fixed beam expander structure with a dynamic focus unit to form a simple three-piece controllable working surface focusing spot diameter optical structure of the beam expander.It is determined through Zemax simulation.The feasibility of the optical structure to control the spot diameter of the working surface was finally assembled based on this structure.An electric beam expander for laser 3D printing was assembled.The beam expander has low cost,simple function and structure,and convenient operation.advantage.In the end of this thesis,the actual working effect of this electric beam expander is verified by experiments.The experimental results show that this beam expander can control the focus spot diameter to vary between 20 ～ 60μm,which meets the actual needs of laser processing.In order to make the use and adjustment of this electric beam expander not limited to a fixed system wavelength,beam expansion ratio,and fixed spot diameter,etc.,this article gives specific design ideas and design steps.The system index needs to be optimized(wavelength,beam magnification,spot diameter,etc.).