substantially uniformly heating or heat insulating a reflection surface of the reflective optical member is provided to prevent overcooling of the reflective optical member application_number US 75402891 A description fig1 shows a schematic construction of a light source device in accordance with a first embodiment of the present invention an elliptic mirror 2 in a lamp house 10 is held by a support plate 10a at an exit 2a of a light beam an electric heater 30 is wound around the elliptic mirror 2 to forcibly heat the elliptic mirror 2 an upper mouth piece of a lamp 1 is held in suspension by an upper support leaf spring 12a which also serves as a lead wire the support leaf spring 12a is connected to a centering mechanism 12 a lead wire 12b is connected to a lower mouth piece of the lamp 1 the centering mechanism 12 three dimensionally moves the lamp in an attitude shown in fig1 in order to bring a light emission point of the lamp 1 to a first focal point of the elliptic mirror 2 shield plates 10b and 10c which shield a highly brilliant illumination light travelling downward from a lower opening 2b of the elliptic mirror 2 and which control a cooling air flow are formed in lamination at.