To eliminate necessity for provision of a relay lens which is expensive.
A lens barrel device 11 to be inserted through the wall of a combustion furnace is equipped with a first cylinder 21 fitted at the outer extremity with an infrared camera 12 or a visible ray camera 13 and furnished near the inner end with a window member 23 to admit passage of the beams of light, a convex mirror 25 installed in the center of an opening at the inner end of the first cylinder, a concave mirror 26 installed at the inner end of the first cylinder for the reflected light by the convex mirror to be reflected on the outer extremity of the first cylinder, a second cylinder 22 arranged at the periphery of the first cylinder in such a fashion as generating a ring-shaped space S, and a first 28 and a second gas supply pipe 29 connected with the respective cylinders for supplying the cooling gas into the first cylinder and the ring-shaped space.
SATO TAKURO
SAITO HIDEKI
ENDO HIDEKI
SAKAGAMI TAKAHIDE
UNIV OSAKA
Yoshihiro Morimoto
Toshiji Sasahara
Yohei Harada