Memoirs of the Faculty of Engineering, Okayama University
Published by Faculty of Enginerring, Okayama University

<Formerly known as>
Memoirs of the School of Engineering, Okayama University

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Second Harmonic Detection of Atmospheric Trace Gases with a Train-Pulse Driven Lead-Salt Tunable Diode Laser for an Operation at Peltier Cooling Temperature

Bouzidi, Moncef
Koga, Ryuji
Wada, Osami
Kagawa, Naoki
Hai, Xu
Sano, Hiroya
Is proposed a tunable diode laser absorption spectrometer system which employs a pulsed current to drive the diode laser still implementing a second-harmonic detection methods enhancing a signal to noise up to 104 times that the case without it. This system affords the lead-salt diode laser a higher operating temperature which allows a more compact deep cooling system. A principle is based on employing a gated integrator between the preamplifier and the lock-in amplifier. Investigations are made on the optimum selection of the gating aperture time interval as determined by response time of the infrared detector and the pulse width of the laser driving current.