Angle-resolved diffuse reflectance and transmittance

This chapter covers the topic of bidirectional reflectance distribution function (BRDF) measurements. These measurements, like the diffuse reflectance and transmittance measurements described in Chapter 7, cover the gamut from highly reflecting but diffuse materials to highly specular, low-scatter, materials. BRDF measurements can often be plagued with artifacts that make them notoriously inaccurate, if performed poorly. Detector linearity, stray light, and poor sample treatment, for example, will contribute to errors. This chapter discusses the various methods for performing these measurements, including laser- and nonlaser-based methods. A comparison between methods that use a radiance source and measure radiance and those that under fill the sample and measure power scattered per solid angle will be made. A number of examples are given.