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Thermally induced focal shift in laser optics

Since the average power of ultrafast lasers is increasing continuously, thermal effects in laser optics cannot be neglected anymore. When the thermal refractive power of a laser optics (e.g. focusing optics) is known, the distance between the focusing optics and the workpiece can be adapted to ensure a fault-free processing result.

As part of the BMBF-project SCULPT, the IFSW hast determined the thermal refractive power of laser optics, from which the thermally induced focal shift can be calculated. Thin lenses made of different substrates (N-BK7 and fused silica) and with different coatings (uncoated, broadband coating and wavelength coating) were investigated. The type of coating can have a much larger influence than the substrate.

The results have been published: https://doi.org/10.1364/OE.26.026020.

Contact: Sebastian Faas und Dr. Rudolf Weber