APPARATUS AND METHOD FOR MEASURING DECAY IN INTENSITY OF ELECTROMAGNETIC RADIATION IN MULTIPASS SPECTROMETRY

摘要

An apparatus for measuring decay in intensity of electromagnetic radiation passing through a radiation-absorbent sample (62) due to absorption of radiation by the sample, includes a source (64) of electromagnetic radiation having a wavelength within an absorption band of the sample and a plurality of partially-reflective specular surfaces (S0, S1, S2...) which are spaced apart from each other along a predetermined path through the sample. Each specular surface separates the incident radiation into a reflected part which follows the predetermined path and an unreflected path. A value of the decay is derived from intensity measurements of the unreflected parts made at different positions along the predetermined path.