Femtosecond laser induced material modification in bulk for dicing display glass plates

Abstract

The invention of femtosecond laser turned out to be a revolution for micromachining dielectric materials such as glasses. The electric field strength of an intense femtosecond laser easily approaches or even exceeds the strength of the electric field that holds the valance electrons in a transparent material to their ionic cores. In this regime, laser energy can be nonlinearly absorbed by the material, leading to a permanent damage. The damage mechanisms of femtosecond laser pulses for different methods and their applications for dicing display glass plates are explored in this thesis. Dicing glass plates using laser pulses has not been conducted much due to the limitation of processing speed while keeping quality at certain level. Therefore, the massive introduction of femtosecond laser for precise and fast cutting of glass plates in industrial applications is still being delayed. In this thesis, I have demonstrated some techniques that can be deployed for dicing display glass plates satisfying the industrial demands. In order to investigate the outcome of the demonstrated techniques, lasing parameters: pulse energy, focusing depth, scanning speed, and numerical aperture of the lens were varied carefully. Using optical microscope (OM), the morphology of the material changes is examined. The material damage inside the bulk of the glass plate is studied for different mechanisms to come up with best techniques.