Disclosed herein is a lamp cooling device for cooling a lamp including a
light emission source for emitting light, a front transparent plate, a
reflector for reflecting light emitted by the light emission source
toward the front transparent plate, the light emission source being
disposed in an intralamp space surrounded by the front transparent plate
and the reflector, said lamp cooling device including: a duct having
joint ports defined in respective opposite ends thereof and communicating
with said intralamp space, said duct having a continuously extending
portion between said opposite ends which is disposed in a space outside
of said intralamp space, for circulating a gas through said duct and said
intralamp space in isolated relation to the space outside of said
intralamp space.