Patent ID: 8217332

Claim:
An optical engine, comprising: an illumination system, for providing a visible beam and an invisible beam; a beam splitting element, disposed in transmission paths of the visible beam and the invisible beam, the beam splitting element comprising: a first dichroic unit, obliquely disposed relatively to the visible beam and the invisible beam; and an optical path turning unit, obliquely disposed relatively to the visible beam and the invisible beam, and kept a distance away from the first dichroic unit, wherein one of the visible beam and the invisible beam from the illumination system is capable of being reflected by the first dichroic unit, the other one of the visible beam and the invisible beam from the illumination system is capable of passing through the first dichroic unit, being reflected by the optical path turning unit, and passing through the first dichroic unit in sequence, and an optical axis of the visible beam and an optical axis of the invisible beam are separated from each other after the visible beam and the invisible beam leave the beam splitting element; a second dichroic unit, disposed in the transmission paths of the visible beam and the invisible beam from the beam splitting element, wherein the visible beam is capable of passing through the second dichroic unit, and the invisible beam is capable of being reflected by the second dichroic unit; and a light valve, disposed in the transmission path of the visible beam from the second dichroic unit, for converting the visible beam into an image beam, wherein the image beam is capable of passing through the second dichroic unit and is combined with the invisible beam reflected by the second dichroic unit.