Calibration, laser absorption

In this paper, a fiber optic remote sensing multiplexed oxygen monitoring system is designed based on tunable diode laser absorption spectroscopy technique. It is an intrinsic sensing method to provide long term stability without the need of frequent calibrations. 

Bulajic D., Corsi M., Cristoforetti G., Legnaioli S., Palleschi V., Salvetti A., Tognoni E., A procedure for correcting self-absorption in calibration-free Laser Induced Breakdown Spectroscopy, Spectrochimica Acta B 2002 57 339-357. 

We present a frequency comparison of two independent -stabilized Nd YAG lasers at 532 nm and an absolute frequency measurement of the laser frequencies which were locked to different HFS components of the R(56)32-0 and P (54)32-0 iodine absorption line. The absolute frequencies have been determinded using a phase-coherent frequency chain which links the 12-stabilized laser frequency to a CH4-stabilized He-Ne laser at 3.39 pm. This laser had been calibrated before the measurements against an atomic cesium fountain clock. 

In 1986, R. BEAUSOLEIL and D. McINTYRE completed their thesis research at Stanford with an absolute frequency measurement of the F = 1 component of hydrogen 1S-2S [11,20], As frequency reference they employed a 486 nm cw dye laser, locked to a narrow absorption line of 1J Te2 vapor. This line was chosen near a reference line, calibrated to within 4 parts in 1010 by A. FERGUSON et al. [21]. Its second harmonic coincides very nearly with the resonance frequency of the hydrogen two-photon transition, so that the frequencies can be precisely compared by observing a radio frequency beat signal. 

Medium-resolution absorption spectrometer emission spectrometer with red-sensitive photomultiplier or CCD detector laser excitation source such as listed in Table 1 (or medium pressure mercury arc such as described in earlier editions of this text) neon calibration lamp and power supply (available from, e.g.. Oriel Corp., Stratford, CT) reagent-grade iodine 100-mm glass cell with Teflon stoppers for absorption studies heating tape with controlling Variac 50-mm cell for emission studies vacuum system, preferably with a diffusion pump and cold trap, for pumping down emission cell. 

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