SEMICONDUCTOR LASER ABSORPTION SPECTROSCOPIC DEVICE

摘要

PROBLEM TO BE SOLVED: To provide a semiconductor laser absorption spectroscopic device capable of measuring accurately a gas concentration by enlarging sufficiently a signal-to-noise ratio even when the gas pressure of a gas to be measured is lower than 10 mbar.

SOLUTION: This device has two resonators comprising a current excitation type surface light emitting semiconductor laser 21 arranged in a gas cell 24 filled with ammonia gas G1 and driven by current excitation, and a concave mirror 23 arranged on the optical path of semiconductor laser light emitted from the current excitation type surface light emitting semiconductor laser 21 and in a gas cell 24. The device is equipped with the first photodiode 52 for receiving a semiconductor laser L1 irradiated toward the ammonia gas G1 and the second photodiode 55 a semiconductor laser L2 irradiated from the current excitation type surface light emitting semiconductor 21. The ammonia gas G1 concentration is measured from the emission intensities of the semiconductor laser lights L1, L2 received respectively by the first and second photodiodes 52, 55.

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