PURPOSE: To provide a concave mirror type converging optical device including a metal halide lamp having a long life and having a reduced deterioration of a converging efficiency by time passage.
CONSTITUTION: A light emission tube 1 of quartz glass in a horizontal lighting type 150W metal halide lamp is bound and fixed to a Pyrex glass moulding 8 forming a reflection mirror on the lamp side inner surface, a Pyrex plate 9 through which visible light is transmitted is bound and sealed to an aperture part 8a of the glass moulding 8, holes 8b, 8c are provided at an upper part and a lower part of the Pyrex glass moulding 8, these holes 8b, 8c are connected to each other by a hollow tube 10, a gas circulation means 12 including a rotary propeller 11 is provided in part of the hollow tube 10, and gas inside the glass moulding 8 is circulated.
OMURA HIDEAKI
ITO YUKO
MONJU HIDETO
TAKEUCHI NOBUYOSHI
