The DEWRay is a precision dewpoint hygrometer which works on the proven fundamental optical dew-point measurement principle (see technology section for detail information). The DEWRay split beam reflex detection method is able to detect whether ice or super-cooled is present on the mirror and compensate accordingly. This feature, unique to STORK Instruments, avoids the possibility of measurement errors of up to 4°C dewpoint which is an inherent danger in competing cooled mirror instruments.