PURPOSE: To measure a particle having a small particle size with high sensitivity by mounting the reflecting mirror for the resonator of a laser oscillator on the side wall of a pipe member for guiding fine particles, and providing a scattered light detecting means on the side wall of the pipe member in the position never directly receiving laser beams.
CONSTITUTION: The light oscillated by a He-Ne laser tube 2 is passed through a blister window 4, reflected by a reflecting mirror 32, and advanced to a reflecting mirror 31 in the tube 2. The laser beam is repeatedly amplified by repeating this. One flange 14 of a pipe member 1 is connected to a vacuum device side, the other flange 15 to the exhaust line on a vacuum pump side, respectively, and the particles in the vacuum device are guided to a particle detecting area 7 in the pipe member 1. The laser beam L is collided with the particles to generate a scattered light M. The scattered light M is converged by a converging lens 5, detected by a photodiode 6, and counted as the particle. Thus, even a fine particle can be detected.
YAMAGUCHI MASANORI
KAMIYA SEISAKU
SATO SHINTARO
UCHIYAMA TAKAHIRO
UEKI KAZUYOSHI
IIDA SHINYA
