PROBLEM TO BE SOLVED: To improve efficiency in maintenance and to process and treat substrates to be processed efficiently by keeping track of the amount of stains adhering to the inner walls of a piping. ;SOLUTION: Holes 32 and 33 are bored in a piping 14, and transparent bodies 34 and 35 are fitted into the holes 32 and 33. Detection light is transmitted through the transparent bodies 34 and 35, and a photosensor 36 is provided for detecting the amount of transmission. By the amount of detection light that is emitted from a projector 36a, transmitted through the transparent bodies 34 and 35, and received at a light receiver 36b, the amount of stains adhering to the inner surfaces of the transparent bodies 34 and 35 is detected and the amount of stains adhering to the inner walls of the piping 14 is grasped.;COPYRIGHT: (C)1999,JPO
展开▼
