Patent ID: 7044609

Claim:
A light source device, comprising: a light-emitting tube including a light-emitting portion that generates a light beam by an electric discharge between electrodes, and sealing portions provided on both sides of the light-emitting portion; and a reflector including a neck portion provided with an insertion hole to which the light-emitting tube is inserted, and a reflecting portion integrally formed with the neck portion and having an ellipsoidal curved reflecting surface that irradiates the light beam emitted by the light-emitting portion to align the light beam in a predetermined direction, the light-emitting tube having a sub-reflection mirror that covers substantially a front half of the light-emitting portion, the insertion hole having a diameter that is enlarged from the base end thereof toward a distal end in a light irradiation direction, the opening diameter of the insertion hole on the side of the reflecting surface being greater than the external diameter of the sub-reflection mirror while the opening diameter is within the internal diameter of a valid reflection area of the reflector, the internal diameter being defined by a front focal position of the reflector and the outer periphery of the sub-reflection mirror, and the internal diameter of the valid reflection area of the reflector being a diameter of a circle defined by a nodal line between the reflection surface of the reflector and a cone which is formed by the boundary of the light beam shielded by the sub-reflection mirror out of the light beam reflected by the reflecting surface of the reflector and condensed to the front focal position of the reflector.