TPDSci Fig Sample and reference cells with the same pathlength Fig Measuring attenuation of light

Measuring attenuation of light: Sample and reference cells with the same pathlength - experimental arrangement

Sample and reference cells

Fig. 1. An experimental arrangement for measuring the transmission of light by a turbid medium by using two identical cells which contain respectively a sample of the medium and a reference medium with unity transmission. The transmission can be converted to the attenuation coefficient with the help of the Lambert law. Abbreviations: A - aperture for limiting the acceptance angle of the detector, BS - beam splitter, C - light chopper; the chopper wheel is shown in an orientation allowing light to pass through the sample cell, S, and blocking light from passing through the reference cell, R; broken lines indicate the beam path when the chopper allows light to pass (by locating the chopper upstream of the cells one prevents potential bleaching of light absorbing centers of the sample), D - detector with a response insensitive to the direction of radiation within the left-hand hemisphere, L - lens, LS - steady-output light source generating a collimated beam, M - mirror, R - reference cell, S - sample cell, W - window. If the synchronous detection method is used to measure the transmitted power, the light beam must be synchronously modulated at different frequencies in each beam path, so that the detector outputs for each path can be resolved (for example, http://www.thinksrs.com/downloads/PDFs/ApplicationNotes/SR540_experiments.pdf).
See also details of the acceptance angle limiting with a lens-aperture system.

CITATION:
Swanson N. L., Jonasz M. 2007. Measuring attenuation of light: Sample and reference cells with the same pathlength - experimental arrangement (www.tpdsci.com/Tpc/AtnCfMsSetSamRefFig.php). In: Top. Part. Disp. Sci. (www.tpdsci.com).

HISTORY:
Published: 21-Nov-2007
Modified: 24-Jan-2008
Peer-reviewed: 22-Dec-2007

Topics in Particle and Dispersion Science