Patent ID: 8063566

Claim:
An illumination apparatus, comprising: a metal vapor discharge lamp including an arc tube having a pair of electrodes therein, an airtight container having a pinch seal part at one end and housing the arc tube therein, and an outer tube having a base at one end facing the pinch seal part and housing the airtight container therein; and an open-type reflector that holds one end of the metal vapor discharge lamp facing the base of the outer tube, and has a concave reflecting surface that is shaped so that a concave diameter gradually expands from the base to an other end of the outer tube along a longitudinal direction of the metal vapor discharge lamp, wherein the outer tube has a light reducing unit provided therein that reduces an amount of light emitted from the arc tube in directions except toward the reflecting surface, so that an amount of light emitted in the directions and passing through the outer tube is smaller than an amount of light emitted in the directions and entering the airtight container.