Abstract
Factory calibration documents for sintered PTFE and painted reflectance standards specify diffuse hemispherical reflectance at 8 degrees incidence, nadir collection. This measurement is an isotropic mean of azimuth angles. In practice, targets are measured at very specific azimuthal incidence and collection angles, requiring more rigorous BRDF knowledge if certainties of less than 2% are desired. In this presentation, a practical method for determining the azimuthal dependence of nadir collected reflectance at various incident illumination zenith angles is described and discussed.
Practical Anisotropy of Reflectance Standards
Factory calibration documents for sintered PTFE and painted reflectance standards specify diffuse hemispherical reflectance at 8 degrees incidence, nadir collection. This measurement is an isotropic mean of azimuth angles. In practice, targets are measured at very specific azimuthal incidence and collection angles, requiring more rigorous BRDF knowledge if certainties of less than 2% are desired. In this presentation, a practical method for determining the azimuthal dependence of nadir collected reflectance at various incident illumination zenith angles is described and discussed.