To effectively prevent heat emitted by light sources from being transferred to thermophobic parts by providing a heat insulating partition wall consisting of at least double partition walls forming a cooling heat insulating passage, between the light sources and the thermophobic parts.

A first partition wall 74 if provided in such a manner as to isolate a projecting lamp 32, an illuminating lamp 64, and a CCD camera 52 from one another, and a second partition wall 76 is provided on the side of the lamps 32, 64 to form a cooling passage 102 through which the heat emitted by the lamps 32, 64 is guided to a cooling fan 70. Heat insulation between the lamps 32, 64 and the CCD camera 52 is thereby achieved and the temperature of the first partition wall 74 is prevented from rising. Further, a cooling fan 72 and a third partition wall 78 are provided on the side of the first partition wall 74 facing the CCD camera 52, to form an exhaust heat insulating passage 104. Thereby the transfer of the heat to the CCD camera 52 via the first partition wall 74 is effectively prevented.