Research And Development Of A Femtosecond Laser Processing System And Its Error Analysis

Two photopoly-merization of femtosecond machining break the limits ofdiffraction of light, and it makes the processing scale reach nanoscales. As a newprecise and ultra-precise method, it attracts more and more researchers’ attention. Butup to now, the devices of the method only used in the experimental stage, and thecontradiction among precision, stage travel and size in microcosmic constraints itsextension and commercialize. So it is necessary for us to integrate the current devicesand to develop a femtosecond machining system which not only have a high precisionbut also have a long stage travel.The dissertation firstly develops a femtosecond system which includes an opticalsystem and a five-degree of freedom stage. The femtosecond laser, shutter, energyamplifier or reductor, mirrors at all levels, CCD camera and the scanner systemstogether constitute the optical system. The5-DOF stage makes use of newtechnologies of linear motor,gas bearing and grating displacement sensor. All axlesinstall in series on the marble, x-axis and y-axis install in orthogonality, A-axis andB-axis also install in orthogonality based on the y-axis, finally z-axis is perpendicularto the marble pedestal and install in parallel with other axis. In order to realize rapidscanning, there exists the scanner system on the z-axis. In addition A-axis and B-axiscombine the linear motor and the piezoelectric oscillating to achieve a slight angle.The5-DOF stage is placed on a marble pedestal which has the ability to vibrationisolation. On this basis, this dissertation models the device and have the modelanalysis.Yaw angle of the femtosecond laser beam directly affect the machining accuracy,so this paper analyzes the relationship between the initial angle of incidence of thelaser beam, laser galvanometer scanning angle and swing angle, so we get the resultthat the swing angle decreases with the initial angle increases and it increases with thegalvanometer scanning angle increase. The swing angle has a good linearity when1010and6090. For a more accurate description of the laser spotposition on the workpiece, this paper also infer the angle of refraction, so it can reflect that scanning angle, angle of incidence and the initial angle of incidence influence theangle of refraction. It varies cyclical changes with all of the factors.This paper analyzes the error of the5-DOF stage that I designed. It builds themodel of errors based on the Multi-body modeling theory, and identified50factorsthat affect the integrated error, in addition it focus on errors of perpendicularitytranslational errors and yaw errors of each axis, and concluded as follows:(1) Theerrors of perpendicularity only have the effect on x-axis and y-axis, it almost has noeffect on z-axis, when the errors of perpendicularity is10, the final error reaches250nm, when errors of perpendicularity is1, the final error reaches nanoscale;(2)Integrate errors in the x-directione xlie on the pitch and x, other errors havelittle effects on it. Integrate errors in the y-directioney lie on the roll and y,other errors have little effects on it too; Integrate errors in the z-directionez onlydepend on the z.(3) Each axis interaction and they determine the comprehensiveerrors of the device.