In-situ diagnostics on fs-laser-induced modification of glasses for selective etching

In-situ observation of the in-volume modification of glasses by focused ultra-short pulsed laser radiation with an interferometer microscope allows for the spatially resolved measurement of the transient optical path difference (OPD) in the surrounding of the laser-induced modification. By the relation of refractive index and temperature an estimation of temperature during modification process is possible. The absorption of the laser radiation is measured and is, together with the estimation of processing temperature during modification, a first step towards a process model for the induced modifications of the transparent material.