Patent ID: 7665867

Claim:
A light source unit, comprising: an arc tube including a front side, electrodes, sealed sections and a light emitting section in which discharging emission is performed between the electrodes and the sealed sections which are provided at both ends of the light emitting section, the light emitting section having a front side and a rear side; an elliptic reflector including a reflecting surface to reflect a luminous flux radiated from the arc tube in a certain uniform direction; and a secondary reflecting mirror having a reflecting surface disposed so as to oppose the reflecting surface of the elliptic reflector, covering the front side of the light emitting section, and reflecting the luminous flux radiated from the light emitting section toward the elliptic reflector, the sealed sections being provided on the front side and the rear side of the light emitting section, the arc tube including a center of discharging emission disposed at a first focal position of the elliptic reflector, the secondary reflecting mirror being mounted on the front side sealed section of the arc tube as a separate member from the arc tube, and an outer peripheral surface of the secondary reflecting mirror being accommodated within a circular cone formed by a line connecting a second focal position of the elliptic reflector and a distal end of the front side sealed section of the arc tube; the secondary reflecting mirror having an adhering surface opposing to an outer peripheral surface of the front side sealed section of the arc tube, and being fixed to the arc tube by applying an adhesive agent between the outer peripheral surface of the front side sealed section and the adhering surface.