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| Measuring attenuation of light: Two sample cells with different pathlengths - experimental arrangement | Parent topic |
Fig. 1. An experimental arrangement for measuring the transmission of light by a turbid medium, using two cells of differing pathlengths (z1 and z2), both containing the same medium. The transmission can be converted to the attenuation coefficient with the help of the Lambert law. Abbreviations: A - aperture 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 cell S1 and blocking light from passing through cell S2; broken lines indicate the beam path when the chopper allows light to pass; by locating the chopper upstream of the cells one reduces the potential for 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, S1 and S2 - sample cells, 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: Two sample cells with different pathlengths - experimental arrangement (www.tpdsci.com/Tpc/AtnCfMsSetTwoPlenFig.php). In: Top. Part. Disp. Sci. (www.tpdsci.com). |
HISTORY: Published: 21-Nov-2007 Modified: 24-Jan-2008 Peer-reviewed: 22-Dec-2007 |
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