The invention relates to a light-emitting device and a
projection system in the technical field of
laser display, the light-emitting device uses a first collimation part and a second collimation part to collimate
laser in a first direction and a second direction respectively, the
laser firstly enters the first collimation part and then enters the second collimation part, and after passing through the first collimation part, the laser passes through the second collimation part and then enters the second collimation part. The laser is collimated in the first direction, and the length of the long
diameter of a
light spot formed by the laser on the second collimation part is equal to the length of the long
diameter of a
light spot formed by the laser on the first collimation part along with the extension of an
optical path; after the laser passes through the first collimation part, the
diffusion angle of the laser in the second direction is reduced but not 0 degree, the short
diameter width of a
light spot formed by the laser on the second collimation part is larger than the short diameter length of a light spot formed by the laser on the first collimation part along with the extension of the
optical path, the short diameter length of the light spot is increased, and the difference between the long diameter length and the short diameter length of the light spot is reduced. The homogenization effect of light spots in the long-diameter direction and the short-diameter direction is improved, and the homogenization effect and the spot
elimination effect of the whole light spots can be improved.