Optical signal detecting circuit, light volume detecting device, and charged particle beam device

• Main Authors: SUGAWARA YUKI, ONISHI FUJIO, TOUDA HIROSHI, OSAWA TETSUJI
• Format: Patent
• Language: English
• Published: 25.02.2015
• Subjects: BASIC ELECTRIC ELEMENTS; COLORIMETRY; ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS; ELECTRICITY; INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIRCHEMICAL OR PHYSICAL PROPERTIES; MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT,POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRA-RED,VISIBLE OR ULTRA-VIOLET LIGHT; MEASURING; PHYSICS; RADIATION PYROMETRY; TESTING

To provide an optical signal detecting circuit, light volume detecting device, and charged particle beam device capable of discriminating, with a simple operation, the signal component of an extremely small amount of light and the signal noise component caused by dark current. A data processor (441) finds the peak value, which is the maximum voltage value of the pulse, by detecting a pulse from a digital voltage signal that corresponds to an amount of light converted by an amplifier (41) and an A-D converter (42), and stores the occurrence frequency for each found peak value in a frequency storage area (451); a data analyzer (442) compares the occurrence frequency of the peak values from the occurrence frequencies of the peak values associated with the peak values stored in the frequency storage area (451) in order from the smallest value to a predetermined lower frequency limit, and sets a pulse determination threshold value to the peak value for which the comparison result occurrence frequency is less than or equal to the lower frequency limit; and a threshold value processor (43) outputs a digital voltage signal that is greater than or equal to the pulse determination threshold value as a detection signal.