There is a growing need in the industry for motorized spectrophotometer accessories. Especially for measurements of directional reflectance and transmittance, which require many scans on the same sample at different angles of incidence, automation is beneficial. TNO TPD has developed a new motorised accessory for the measurement of directional reflectance and transmittance in the wavelength range between 250 and 2.500 nm. It is capable of making absolute measurements of the transmittance and reflectance of specular samples as well as performing BRDF measurements on diffuse samples. The accessory is a valuable tool in the optical characterisation of coatings and provides a means for analysis that yields the thickness and optical constants of the individual layers in multi-layer coatings, as well as other parameters that can be related to optical material properties. (C) 2003 Elsevier Science B.V. All rights reserved.