multiple-pass cell

in spectrochemical analysis
Permits multiple passage of radiation to increase the absorption pathlength. It is constructed in such a way that mirrors either form part of the cell or are mounted in the sample cell holder.
PAC, 1988, 60, 1449. 'Nomenclature, symbols, units and their usage in spectrochemical analysis - VII. Molecular absorption spectroscopy, ultraviolet and visible (UV/VIS) (Recommendations 1988)' on page 1454 (