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Optical characterisation of materials and systems for daylighting
journal contributionposted on 2001-01-01, 00:00 authored by G B Smith, D C Green, G McCredie, M Hossain, P D Swift, Mark LutherMark Luther
The measurement of BRTF (Bi-directional reflectance and transmittance function) is described using a new instrument which is capable of supplying BRTF data and algorithms for use in computer simulations directly on diffuse materials and indirectly on large samples and sub-systems. A high sensitivity and dynamic range is needed to achieve low minimum observable BRTF and the role of angular resolution are discussed with examples. Forward scattering with extended tails is found to dominate pigmented polycarbonate. Slatted blinds are discussed as examples of systems where azimuth is important.