Femtosecond Laser Surface Micro-nano Processing Based On Space Light Modulation Technology

As a new multi-purposed nanomaterial processing technology,the surface micro-nanostructures processed by femtosecond laser are widely used in many fields,such as physics,biology and information.The spatial light modulation technology based on LCoS SLM(Liquid Crystal on Silicon-Spatial Light Modulator)can realize the spatial shaping of femtosecond laser focal plane light field through phase modulation,which can apply to the parallel processing without mask,so as to ensure the processing precision as well as to raise the efficiency much higher than the traditional point by point scanning processing technology.This work introduces the structure and working principle of spatial light modulator,and does some analysis,simulation and improvements on a series of optical field graphics algorithms based on LCoS SLM.A series of experiments are applied to verify that.This work will investigate and summarize principles of a spatial shaping system based on the spatiotemporal interference which is more easy,flexible and efficient than traditions.However,the imaging distortion introduced by the shrink-beam system has huge influence on the accuracy of processing.This work simulates and analyzes the distortion of the systems,and provides a method to adjust the phase hologram from a spatial light modulator via compensating for the position changes and the uneven light distribution from the distortion.The method can make the maximum deviation of the interference pattern near the exposure point approach 0 from 10.66 ?m,the relative maximum deviation reduce from 60.42 % to under 8% and the two-dimension light intensity distribution get close to flat-top.The algorithm reduces the design requirement on the system,cost and time are saved.The high-precision large-area micro-nanostructures are realized successfully fabricated on a stainless steel surface based on this system,including the 1.5 × 1.5 mm QR code with multi-level anti-counterfeiting ability.Furthermore,the multiplexed Fresnel lens hologram are simulated by using the MPFL(Multiplexed Phase Fresnel Lenses).The cylindrical lens hologram is obtained by improving simulation,which modulates the laser field into dot matrix and linear distribution.By using the GS algorithm and the GSW algorithm,a computer hologram to modulate the light field into a planar distribution is obtained.The light intensity uniformity is immensely improved at the focal plane.