Determination of directional optical properties of an electrochromic device

Abstract In this paper we discuss the methods for measuring directional optical properties of coated glass samples. Spectral data and reflectance and transmittance coefficients for visible daylight and solar radiation are presented, obtained for unpolarised radiation at (near-)normal and oblique (30° and 60°) incidence on an electrochromic device in the bleached state as well as in the coloured state. At low angles, the reflectance in the bleached state is larger as compared with the reflectance in the coloured state. The opposite is the case at larger angles. Furthermore, the results demonstrate a stronger angular dependency of the optical properties in the coloured state as compared with those in the bleached state. Comparing visible light transmittance with solar transmittance, coloration had a greater effect on the solar transmittance.