The SLE (Selective Laser-Induced Etching) process is a two-stage process:

First, transparent material is exposed to laser radiation in such a way that the chemical etchability is increased at these points. To ensure that this is achieved without cracking, a short pulse duration (fs-ps) and a small focus volume (a few µm3) are required. The focus is then moved through the material until a contiguous volume in contact with the outer surface of the workpiece is exposed.

In the second process step, the material modified by the laser radiation is selectively removed by wet chemical etching—the structure is essentially developed. Selectivity—the etching rate of the modified material in relation to the etching rate of the unmodified material—is essential for structural accuracy.