摘要:
The present invention includes: an outer casing (15) that is formed in a bottomed tube shape, has a cooling water supply port (23) through which cooling water (W) is introduced, and a cooling water discharge port (22) through which cooling water (W) is discharged formed at a rear end (15b) in the direction of an axis (O1), and is inserted into a high-temperature furnace; an inner casing (16) which is formed in a bottomed tube shape and inserted into and disposed in the outer casing (15), and into which cooling air (S) is supplied; an imaging unit (19) that is disposed in the inner casing (16) and captures an image of the exterior of the outer casing (15); and partition members (20 and 21) that are between an inner surface of the outer casing (15) and an outer surface of the inner casing (16) and define a first flow channel (R1) for leading the cooling water (W) toward a front end (15a) in the direction of the axis line (O1) between the inner surface of the outer casing (15) and the partition members, a second flow channel (R2) for leading the cooling water (W) toward the rear end (15b), and a communicating channel (R3) for communicating the first flow channel (R1) and the second flow channel (R2) between the bottom of the outer casing (15) and the partition members.