[OPTICAL REVIEW Vol. 9, No. 1 (2002) 18-24]

Combination of a Gated Phtotomultiplier Tube and a Phase Sensitive Detector for Use in an Intensive Pulsed Background Light Situation

Tetsuo IWATA1,*, Tsuyoshi TAKASU1, Tsuyoshi MIYATA2 and Tsutomu ARAKI3

1Department of Mechanical Engineering, University of Tokushima, Minami-Jyosanjimacho-2, Tokushima 770-8506 Japan, 2Department of Mechanical Engineering, Niihama National College of Technology, Niihama, 792-8580 Japan, 3Department of Systems and Human Science, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531 Japan

(Received July 26, 2001; Accepted December 4, 2001)

In order to detect a weak signal light that appears after an intensive pulsed background light, we constructed a light detection module that consisted of an internally-gated photomultiplier tube (PMT) and a phase sensitive detector (PSD). Plural even-numbered dynodes of a miniature PMT were controlled for the internal gate operation and the output signal from the PMT was fed into the PSD integration circuit (IC) that worked synchronously with the gated PMT. The module acts as a sort of lock-in light detection system. The combination of the gate-on PMT and the PSD IC detects the weak signal light while the gate-off PMT rejects the intensive pulsed background light. From fundamental performance tests, we found that a background rejection ratio (BGRR) of the gated PMT up to 10,000 could be obtained. We carried out an evaluation experiment using a multi-white light-emitting diode (LED) to demonstrate the pulsed-background-light rejection capability of the module.

Key words: gated photomultiplier tube, phase sensitive detector, multi-white LED, spectroscopic techniques, instrumentation