| 摘要 |
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.
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