Abstract
Inner holographic marking is demonstrated. A Gaussian-like profile LD-pumped Nd: YLF laser has beenemployed to generate the second harmonic (523nm) pulses. When the laser beam is strongly focused insidethe soda lime glass plate, the refractive index of the glass substrate changes slightly and a small bright spotappears inside the plate. The spot is so small that we have to use some microscopes to detect the spot. For thepurpose of the industrial use of this marking method, the visibility to the human eye is the most importantfactor. The periodic structure inside the glass plate made it possible to increase the visibility of the mark andalso the holographic color for the human eye. Inner holographic marking is suitable for the industrial markingprocess for the machine-readable marking and the clean process inside the thin glass substrate without anysurface damages.
