A novel method for holographic femtosecond laser parallel processing using digital blazed grating and the divergent spherical wave

摘要

A novel method for holographic femtosecond laser parallel processing is proposed, which can suppress the interference of zero order light effectively and improve the energy utilization rate. In order to blaze the target pattern to the peak position of zero-order interference, a phase-only hologram containing digital blazed grating are designed and generated, The energy of the target pattern can be increased to 5.297 times in theory. In addition, by subsequently increasing the phase of divergent spherical wave, the focal plane of the target pattern and the plane of multi-order diffraction beam resulted from pixelated structure of the spatial light modulator (SLM) can be separated. Both the high pass filter and aperture are used to eliminate the influences of zero-order light and multi-order interferential patterns simultaneously. A system based on the phase-only SLM (with resolution of 1920*1080) is set up to validate the proposed method. The experimental results indicate that the proposed method can achieve high quality holographic femtosecond laser parallel processing with a significantly improved energy utilization rate.