A referenced and stabilized optical measurement system includes a light source, a plurality of optical elements and optical fiber assemblies and a detector arranged to compensate for the effects of system variation which may affect measurement performance. A non-continuous light source provides a common source light on a common source path. A reference light and a measurement light are derived from the common source light and propagated across separate paths of optically matching optical components in order to produce a common signal variation on both the reference light signal and the measurement light signal. Light paths exposed to air are contained indiscrete volumes for purging gasses from the volumes. Ratios of the reference signal and measurement signal are acquired under various conditions for compensating the measurement signal for system variations.