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Optical Engineering

Trace analysis of water pollutants by photothermal phase shift spectroscopy with an integrated optical microinterferometer
Author(s): Werner N. Faubel; Bernd S. Seidel; Hans-Joachim Ache
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Paper Abstract

Photothermal phase shift spectroscopy measures the changes of the refractive index, induced by a modulated excitation light beam, by a double microinterferometer, consisting of a 7.5 × 7.5 mm integrated optics silica chip. A laser diode that is integrated at the chip is used as the probe laser. The flowthrough cell containing the analyte is mounted in one of the two arms of the Michelson interferometer between the microchip and the reflecting mirror. The great potential of this photothermal microinterferometer as a routine method for process control or environmental surveillance lies in the miniaturization of the system for the following reasons. No adjustment is needed because only fixed components are used. The quality of the light beams is significantly improved by shortening the light paths and very small sample cell volumes in the range of nano- or microliters are needed. This has at least two distinct advantages. On the one hand, a small, compact analytical apparatus enables direct real time and on site measurements. On the other hand, it is possible to build a robust and reliable device, without any movable parts, that is unaffected by external influences.

Paper Details

Date Published: 1 December 1996
PDF: 7 pages
Opt. Eng. 35(12) doi: 10.1117/1.601091
Published in: Optical Engineering Volume 35, Issue 12
Show Author Affiliations
Werner N. Faubel, Forschungszentrum Karlsruhe (Germany)
Bernd S. Seidel, Forschungszentrum Karlsruhe (Germany)
Hans-Joachim Ache, Forschungszentrum Karlsruhe (Germany)

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