PROBLEM TO BE SOLVED: To perform optical amplification, while preventing excessive incidence of light into a photodetector.SOLUTION: An optical measuring system includes: an optical amplification unit 106 a photodetector 108 and a first control section 110. The optical amplification unit 106 amplifies incident light. The photodetector 108 generates electric signals according to a received light amount. The first control section 110 executes preliminary detection control, main gain determination processing, and main detection control in a sequence. In the preliminary detection control, a gain of an optical amplifier is adjusted to a first gain. A preliminary signal is generated according to the received light amount of preliminary light amplified with the first gain. In the main gain determination processing, a second gain is determined to be a main gain when a signal strength of the preliminary signal is less than a threshold level. When the signal strength of the preliminary signal is larger than the threshold level, a third gain is determined to be the main gain. In the main detection control, the gain of the optical amplification unit 106 is adjusted to the main gain. A detection signal is generated according to the received light amount of the detection signal light amplified with the main gain. When the second gain is determined to be the main gain, the light amount of the incident light is calculated based on the detection signal.COPYRIGHT: (C)2013,JPO&INPIT【課題】光検出器への過大な光の入射を防ぎながら、光増幅する。【解決手段】光計測システムは、光増幅ユニット106、光検出器108、および第1の制御部110を備える。光増幅ユニット106は入射光を増幅する。光検出器108は受光量に応じた電気信号を生成する。第1の制御部110は予備検出制御、本利得決定処理、および本検出制御を順番に実行する。予備検出制御において光増幅器の利得を第1の利得に調節する。第1の利得で増幅された予備光の受光量に応じた予備信号を生成する。本利得決定処理において予備信号の信号強度が閾値より低い場合には第2の利得を本利得に定める。予備信号の信号強度が閾値より高い場合には第3の利得を本利得に定める。本検出制御において光増幅ユニット106の利得を本利得に調節する。本利得で増幅された検出信号光の受光量に応じた検出信号を生成する。第2の利得を本利得に定めた場合には検出信号に基づいて入射光の光量を算出する。【選択図】図1
