Design And Verification Of Femtosecond Laser Parallel Scanning Optical System

Scanning using ultra-fast laser micro-machining equipment has unique advantages in the field of micro-machining.However,conventional ultra-fast laser micro-machining equipment uses a single-beam scanning technology,which makes it difficult to improve the processing efficiency of batch operations with limited motor speed increase.The introduction of laser beam splitting technology is a good solution to this problem,allowing the equipment to generate multiple beams for parallel scanning processing and improving processing efficiency for high-precision operations.Therefore,it is of great research significance and application value to improve the optical system of ultra-fast laser micro-machining equipment and design a femtosecond laser parallel scanning optical system.In this paper,the design scheme of the optical system is first formulated.Based on the optical system in the ultra-fast laser micro-machining equipment,the design plan of the femtosecond laser parallel scanning optical system is developed,including technology selection,system optical path diagram,and key component selection,In order to address the phenomenon of zero-level optical interference when the Liquid Crystal Spatial Light Modulator(LCSLM)is loaded with the Computer Generated Hologram(CGH)to complete laser beam splitting,a method is proposed to replace the CGH loading into the LCSLM with a Dammann grating grayscale map.The design flow of the optical system is developed according to the system module division and design path;the main problems faced in the design of this paper are presented and the solutions are given.The module design of the optical system was completed in two parts,non-ZEMAX optical design and ZEMAX optical design.The structural design of the Dammann grating in the beam splitting module was completed in the simulation software,and the single-factor error analysis of the beam splitting effect was carried out,and the script file and UI interface for generating grayscale maps were written in MATLAB.The structural design optimization of optical components in the optical system module,image quality evaluation and function presentation were carried out in ZEMAX.In addition,a femtosecond laser parallel scanning optical system was set up in ZEMAX,and the image quality of the optical system was evaluated under parallel line-plane type and spin-cut scanning,and the indexes were verified in turn.Temperature analysis was performed in the range of-20°C to 60°C to analyze the system performance influenced by the ambient temperature.To ensure that the optical system still meets the requirements after the actual processing and building,a tolerance analysis was performed,and a Monte Carlo algorithm showed that the system has a 75% probability of still meeting the index requirements.Finally,according to the design specifications of the optical system to be verified,the system optical path in the design scheme was partially adjusted,and the laser beam splitting verification system based on Liquid Crystal on Silicon Spatial Light Modulator(LCOSSLM)was built on the optical system platform,loaded with the generated Dammann grating grayscale map and three sets of experiments were conducted.Based on the laser beam splitting verification system,an improved laser parallel processing verification system based on LCOSSLM was built,and experiments were conducted to investigate the effects of changing scanning speed and single pulse energy on the consistency of parallel processing.The design results and test results show that the femtosecond laser parallel scanning optical system designed in this paper meets the design index requirements,the image quality evaluation and index verification results in the simulation are good,there is no zero-level optical interference when multiple beams are generated in the optical platform test,and the beam splitting uniformity and parallel processing consistency meet the design requirements.