Optical design of the DRA system. The diagram is available in the spectrometer manual. The measurement process can be described in five steps: 1. The sample beam hits mirror M1 and is then reflected to M2. 2. The beam travels through the lens and is focused into the transmission port, and onto the reflectance port. 3. The reflected beam is diffused throughout the sphere before being measured by the detector. 4. The reference beam enters the sphere directly through the reference port and is scattering. 5. The hemisphere albedo was then measured.