The Portable Goniometer
The Bidirectional reflectance distribution function (BRDF) of a material describes how much light is reflected in all directions as a function of the angle of its illumination source. Measuring BRDF using Goniometry has historically been a time consuming process that requires a large apparatus with several moving parts.
Measuring the Bidirectional Reflectance Distribution Function
Our new experimental device concept prototype is built around a camera viewing the inside of a cardboard hemisphere which acts as a light controlled environment, with a series of strategically placed light sources with known spectra that illuminate a sample, which in turn illuminates a series of reflective lines painted into the inside of the hemisphere. When the sample is illuminated from a particular angle, the device can take a picture of the reflective lines and use software to analyze the image and calculate BRDF values at a range of positions for that angle of incidence. This compact and lightweight device will allow researchers to rapidly gather BRDF values for a sample, either in a lab, or in the field.