The disclosure relates to an augmented reality apparatus and an optical system therefor. The optical system comprises an image source; a beam splitter component having a beam splitting side adjacent to the image source and a transmission side facing away from the image source; a wave plate adjacent to the beam splitting side, the beam splitter component being arranged in such a way that light emitted from the image source is able to be non-perpendicularly incident on the beam splitting side and at least partially reflected toward the wave plate; and a semi-reflector located downstream of the wave plate in an optical path of the reflected light, wherein the beam splitter component is configured in such a way that when the light emitted from the image source is incident on the beam splitting side, a polarized light component, whose polarization is in a first direction, passes through the beam splitter component to be transmitted through the transmission side, and a polarized light component, whose polarization is in a second direction perpendicular to the first direction, is reflected by the beam splitting side toward the wave plate, and wherein the beam splitter component is also configured in such a way that when light is incident on the transmission side, a polarized light component of the light polarized in the first direction is able to pass through the beam splitter component to be transmitted through the beam splitting side, and a polarized light component of the light polarized in the second direction is able to be absorbed in the beam splitter component, wherein the wave plate is preferably a quarter-wave plate. Using the inventive technical means, influence of unwanted light on the image quality can be eliminated and in the meanwhile influence of stray light can be eliminated.