Optical design and manufacturing principles of DUV and UV f-theta lenses for femtosecond laser material processing

F-theta lenses optimized for DUV (257 nm, 266 nm) and for UV (343 nm, 355 nm) wavelengths entail special optical design and manufacturing challenges. We describe the design principles with a special focus on refractive and diffractive color-correction strategies for ultra-short pulsed lasers (> 190 fs), in order to reduce the focal spot ellipticities caused by lateral color aberrations. Circular spots are needed for exact contour cutting and drilling of hardened glass, e.g. Exemplary simulations of nominal performance, physical effects such as group delay dispersion and a first prototype of a colorcorrected (hybrid) prototype lens for 343 to 346 nm central wavelengths are shown.