Configuration of ring-down spectrometers for maximum sensitivity1

Cavity ring-down (CRD) spectrometers used for analytical applications frequently have design requirements different from spectrometers used for gas-phase spectroscopic applications. A formalism that allows for maximization of the relative sensitivity by adapting the cavity length and absorption path through the sample is presented. These experimental configurations may not reduce the detection limit but do allow for a high sensitivity of the ring-down time measurement in the concentration range of interest. The formalism is applied to two common CRDS experimental configurations and to a fiber-loop ring-down experiment. [PUBLICATION ABSTRACT] Key words: cavity ring-down (CRD), absorption, detector, fiber-loop, sensitivity, detection limit.