| 摘要 |
PROBLEM TO BE SOLVED: To provide a particle counting apparatus capable of judging the stain state of a light transmitting window with high sensitivity. SOLUTION: The particle counting apparatus includes a light source 281 for irradiating a measuring target region 40 in a vacuum state or a close vacuum state with a light through a light incident window 24; a scattered light detector 32 for detecting the scattered light which occurs by irradiating the measuring target region 40 with light, through a detection window 30; a vacuum gauge 12 for measuring the degree of vacuum of the measuring target region 40; a signal processing part 13 for converting a scattered light detection signal to an electrical signal; and a stain discriminating part 19 for discriminating the stain state of the light-transmitting window from the time average value of the electrical signal and the degree of vacuum. COPYRIGHT: (C)2010,JPO&INPIT
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