OPTODYNAMIC ANALYSIS OF DIRECT LASER WRITING OF GRADUATION LINES

The direct laser writing of graduation lines in Cr thin films on glass substrates has been investigated. The Nd-YAG laser and the astigmatic optical system have been used to write rectangular holes in the Cr fi lm. The optimal writing parameters: the laser pulse energy, the Cr lay er thickness and the substrate-objective distance were determined usin g the optoacoustic probe beam deflection method to detect the evaporat ion of the material. The evaporation is concluded to be the essential process in the laser writing of graduation lines. The rims formed by t he surface tension gradient at the hole edges indicate that the laser writing of graduation lines is a typical two-phase removal process.