Gaussian to tophat beam shaping metasurface for visible light

We propose a metasurface optical element made of silicon nitride that converts a Gaussian beam into a tophat-shaped line beam in the visible light region. This allows optical cut-off ranging sensors to achieve higher performance without size enlargement. The metasurface is 4.8 mm square and can convert a gaussian beam with a diameter of 4.6 mm into a tophat-shaped line beam with 30.1 mm at the image plane of a 60 mm distance from the metasurface and simultaneously deflect it by 14.5° from a 0th order light. When the fabricated metasurface was irradiated by laser, the 0th order light and line beam were separated, and the intensity distribution of the line beam was a tophat profile with an FWHM of 29.7 mm (1.32 % error).