Improved resist treatment for gray tone lithographic beam shaping element fabrication

We designed a refractive beam shaping element, which forms a line shaped beam out of a Gaussian output beam of a laser diode. Using a geometric optical method based on the thin element approximation (TEA), a refractive element with a height of 45 μm and a foot print of about 1200×500 μm was designed. The beam shaping efficiency we measured by 90%. The final element is fabricated in fused silica. We developed a process which keeps the surface profile and gives the resist the necessary stability for etching. With this process we achieved a high form stability of arbitrary profiles sufficient for the proportional transfer even by ICP-etching (inductive coupled plasma etching). Based on this technology we fabricated the beam shaping elements and lens arrays.