Multidirectional smoothing by spectral dispersion scheme based on hybrid dispersion grating

A hybrid dispersion grating consisting of several segments of different groove types and groove densities is designed to disperse the laser beam and eventually to redistribute the speckles of the laser beam in different directions (linear, radial, and azimuthal). The elaborately designed redistribution of the speckles significantly improves the irradiation uniformity of the focal spot. As the focal spot is smoothed in at least two of the three directions, the scheme using the hybrid dispersion grating is called multidirectional smoothing by spectral dispersion. Results indicate that the performance and feasibility of the multidirectional smoothing scheme are better than the smoothing scheme based on a linear grating or a star grating. (C) 2018 Optical Society of America.