In-system optimization of a computer-generated hologram using laser-induced luminescence for parallel femtosecond laser processing

A computer-generated hologram (CGH) is optimized in an optical system. The in-system CGH optimization method automatically generates a shaped beam that compensates for the imperfections in the optical system. A new in-system CGH optimization method using luminescence induced by holographically generated parallel beams was developed. In contrast to previously demonstrated in-system CGH optimization methods that directly measure the laser beam with an imager in a different space from the sample, the developed method measures the beam state passing through the objective lens on a sample under a laser fluence at the same level as that used in laser processing. Therefore, the developed method enables CGH design that reflects the state of the laser beam on the sample and is effective for femtosecond laser processing at high laser fluences.