The Dual Radiometric Module unit (DRM) is a tool used to measure the light outputs from Digital Light Lab’s PhotoDSC system. This unique precision instrument measures the light as perceived in the sample and reference cells. The DRM’s detector is identical to the cell location in DSC systems, which provide the most accurate radiometer possible for verifying the light output. The DRM is crucial in checking for any drift of a PhotoDSC system, as well as a useful tool for installation and operation qualifications. Ideally, the DRM and PhotoDSC systems need to be purchased at the same time as they are calibrated together at the time of purchase.