Study On Technology Of Laser Direct Writing Photolithogrophy

Laser Direct writing (LDW) is an advanced fabrication technique for diffractive optical elements (DOE's). So far the level of fabricating by LDW technique is too low to satisfy the demands of the application in China. Study on technology of laser direct writing photolithography based on Cartesian and Polar coordinate by using four-axis LDW system in this dissertation. Several DOE's fabricated by LDW have been applied in practice. The works have laid a foundation for developing more advanced LDW technology.Intensity distribution in photoresist is analyzed during LDW exposure process in terms of the improved theoretical model and the method of selecting the optimal exposure is described. Results of ray-tracing using ZEMAX that is optical design software agree well with the calculated results of theoretical model and L DW experimental results verify the accuracy of the model. Therefore this improved model is important significant for directing LDW research. LDW photolithography in Cartesian coordinate is developed and photolithographic fabrication techniques by using defocusing LDW is creatively presented. The grating and reticle, which linewidth errors are less than 10% nominal linewidth, are fabricated by LDW. For the first time metallic mesh film with area 200mm×200mm fabricated by using LDW photolithography and coating technology. The fabrication accuracy of the mesh structure fabricated by LDW technique is excellent. The optical and electrical performance parameters of metallic mesh film made by LDW approximate the theoretical design values.LDW technology in Polar coordinate is also developed in this paper. Several key techniques that only exist in polar coordinate have been used in LDW processing. An efficient experiential formulation that indicates the relation between linewidth and laser power corresponding to various radial positions under constant angular velocity is presented based on the definition of exposure. The concentric-circle scales are manufactured by LDW and both position accuracy and linewidth of circular line reach the demands of design. Finally, LDW technology on spherical substrate is discussed. The problems in writing process are analyzed in detail and its solutions are given. Some primary experimental results are provided.