Particle counter

Abstract

The present invention provides a particle counter capable of sensitively determining the contamination level of a light transmission window. The particle counter according to the present invention includes: a light source 281 for emitting light through a light incident window 24 to a measurement area 40 in a vacuum state or in an approximately vacuum state; a scattered light detector 32 for detecting scattered light through a detection window 30, the scattered light being generated when a light is delivered to the measurement area 40; a vacuum gauge 12 for measuring the pressure of the measurement area 40; a signal processor 13 for converting a detection signal of the scattered light into an electrical signal; and a contamination level determiner 19 for determining the contamination level of the transmission window from the time average of the electrical signal and the pressure.

Dependencies are inferred from the claim text.