Optical Coatings & Materials Knowledge Base
A diffuse reflectance material or coating is one which exhibits Lambertian reflectance. A perfect Lambertian reflector (which doesn’t exist in reality, although Labsphere’s Spectralon comes very close to realising this ideal) is one in which the reflected intensity (i.e. flux per unit solid angle) varies with the cosine of the angle subtended between the normal to the surface and the direction of view. So the intensity is at a maximum in the direction of the normal to the surface and drops to zero at 90°.
The parameter normally used to define the degree to which a material approaches the ideal of Lambertian reflectance is called the Bi-Directional Reflectance Distribution Function (BRDF). BRDF is the ratio of incident irradiance to reflected radiance for a given direction of illumination and defined direction of viewing. BRDF has the units of inverse steradians (sr-1). The BRDF of a perfect diffuser is 1/π.
Coincidentally, the radiance or luminance (flux per unit solid angle per unit area) reflected from a perfect diffuse reflector is constant with direction of view.
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Technical DocumentationA library of technical documentation relating to Labsphere's diffuser reflectance materials and coatings, including material safety data sheets and handling, application and care instructions. |
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Frequently Asked QuestionsWe have compiled a list of answers to frequently asked questions relating to Labsphere's diffuse reflectance materials and coatings. |
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Glossary of TermsOur glossary of terms helps you to navigate your way through the jargon used to describe the properties and characteristics of diffuse reflectance materials and coatings. |