Patent ID: 7364311

Claim:
An illumination device, comprising: an arc tube including a light-emitting portion; a reflector including a reflective surface that reflects light from the light-emitting portion to an illuminated region; and an auxiliary mirror that is disposed facing the reflector with the light-emitting portion sandwiched therebetween, the auxiliary mirror including a reflective surface without mold marks and which reflects part of the light emitted from the light-emitting portion towards the light-emitting portion, the auxiliary mirror being an auxiliary mirror manufactured by an auxiliary mirror manufacturing method including: a first step of forming a tube by heating a tube including a material of the auxiliary mirror, thereafter putting the tube in a form block, applying internal pressure with an inert gas to cause a center portion of the tube to expand, so that part of an inner surface of the expanded center portion includes a shape corresponding to the reflective surface of the auxiliary mirror; a second step of cutting the tube at the center portion to form an auxiliary mirror member; and a third step of forming a reflective layer on an inner surface of the auxiliary mirror member.