US Patent 7417732 Particle monitoring apparatus and vacuum processing apparatus

A particle monitoring apparatus including a light source configured to emit plural light fluxes, a projecting optical system configured to convert the plural light fluxes into a band-shaped light flux, to lead the band-shaped light flux into a flow passage of a given gas stream, and to partially superpose the plural light fluxes to form a substantially uniform light intensity distribution of the band-shaped light flux in a widthwise direction; a light detector configured to detect intensity of light; and a particle detector configured to determine sizes of the particles passing the light flux based on intensities of the scattered lights detected by the light detector and to count the number of the particles.