Dual Wavelength Method for Molecular Difference Absorption Measurements in Turbid Media
Authors: Liger, Vladimir; Zybin, Alexander; Bolshov, Mikhail; Niemax, Kay
Source: Applied Spectroscopy, Volume 56, Issue 2, Pages 50A-69A and 145-274 (February 2002) , pp. 250-256(7)
Publisher: Society for Applied Spectroscopy
Abstract:
A dual wavelength differential absorption method for the detection of inclusions in turbid media is proposed. The method is based on the measurement of the transmitted intensity differences of the two diode lasers tuned to selected wavelengths within a broad absorption band of an inclusion of interest. The strategy for the optimum selection of the diode laser wavelengths and initial adjustment of the detection scheme is developed. It is shown that small deviations in the wavelengths from an optimum position result in a considerably deteriorated background suppression. The method is demonstrated by the detection of two dyes in a small volume inside a phantom filled with a turbid medium with scattering and absorption coefficients similar to those of biological tissues. The type and relative concentrations of the dyes were chosen so that the optical properties at the laser wavelengths are similar to those of a mixture of oxy- and deoxy-hemoglobin. The proposed method is insensitive to inclusions in the test object with spectrally independent scattering and absorption but detects the changes of the dye composition of a few percent inside a small sub-volume. The technique can be useful for the detection of the physiological status and changes in biological tissues.Keywords: DIODE LASER; DIFFERENTIAL ABSORPTION; TURBID MEDIA; MEDICAL DIAGNOSTIC
Document Type: Research article
DOI: http://dx.doi.org/10.1366/0003702021954511
Publication date: 2002-02-01
- The Society publishes the internationally recognized, peer reviewed journal, Applied Spectroscopy, which is available both in print and online. Subscriptions are included with membership or can be purchased by institutional or corporate organizations. Abstracts may be viewed free of charge. Previously published as Bulletin (Society for Applied Spectroscopy)
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- By this author: Liger, Vladimir ; Zybin, Alexander ; Bolshov, Mikhail ; Niemax, Kay

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