Development of a laser writing system for the fabrication of micro-optical elements

A laser writing system using a 325-nm UV laser beam for the fabrication of micro-optical elements is developed. The system consists essentially of a laser source, an optical subsystem, a movable stage, a computer, and an observation and alignment subsystem. The laser writing system is characterized for the resolution of the system and optimal writing conditions, based on the objective of fabricating micro-optical elements. The resolution of the laser writing system is 1.2 mu m, obtained with the 40x UV objective lens at a writing speed of 100 mu m/s, writing height of 6 mu m and laser intensity of 1 mu W. This agrees fairly well with the calculated theoretical value. We have shown that the laser intensity, writing speed, writing height are three major parameters that determine the optical performance of the micro-optical elements fabricated by the laser writing system. The variation of the thickness and linewidth of the written pattern with the different laser intensities, writing speeds and writing heights are discussed.