Phase noise measurement of a narrow linewidth CW laser using delay line approaches.

Two different laser phase noise measurement techniques are compared. One of these two techniques is based on a conventional and low-cost delay line system, which is usually set up for the linewidth measurement of semiconductor lasers. The results obtained with both techniques on a high-spectral-purity laser agree well and confirm the interest of the low-cost technique. Moreover, an extraction of the laser linewidth using computer-aided design tools is performed.

Radon concentrations in Algerian oil and gas industry.

Concentrations of 222Rn in produced water, crude oil, natural gas (NG) and natural gas liquids (NGL) in on-shore Algeria were measured using scintillation cell techniques (Lucas cells) and electret ion chamber (EIC). The first method, active, is based on the use of a Lucas-type scintillation chamber in conjunction with a portable monitor (model Pylon AB-5); the second method, passive, using an EIC with a 4 l glass analysis bottle. The activities of 222Rn were in the range of 0.98-18.50 Bq/l for produced water, 0.02-0.3 Bq/g for crude oil, 40-1000 Bq/m(3) for NG and 300-2500 Bq/m(3) for NGL, respectively. These values are compared with concentrations reported for other countries.