The present disclosure provides a light source assembly including a light source and a bull's eye collimation structure disposed on a light exiting side of the light source and configured to collimate light beam emitted by the light source. The bull's eye collimation structure includes a metal layer including a sub-wavelength aperture and a plurality of annular recesses surrounding the sub-wavelength aperture, the plurality of annular recesses being arranged along a radial direction of the sub-wavelength aperture.