The Refractor Module adds the ability to model 3D refractors. Refractor elements are modeled in the same way as reflector elements, so there is almost nothing additional to learn. General refractors are modeled by drawing the actual prism or lens geometry in your CAD program. Photopia uses the index of refraction and the extinction coefficient of the material to accurately model refraction into the material, Fresnel reflections from the inner and outer surfaces of the material, total internal reflection (TIR) effects and losses due to absorption within the material. The Refractor Module can be used for LED modeling and lens design, roadway refractors, Fresnel lenses, light pipes, signaling lenses or any other design for which you need to control light using refraction. These analyses go beyond the scope of the Foundation with the BRDF/BTDF material library, which will only analyze refractors that are both isotropic (not orientation dependent) and available for measurement by Lighting Technologies. Note that isotropic prismatic lenses, white translucent lenses and perforated surfaces are available in the General Materials Library and do not require the Refractor Module.

The Refractor Module is capable of modeling various surface treatments on the outer surfaces of the refractor such as etching, sandblasting or painting. This makes it possible to model light pipe systems using various material treatments to extract light from the system. The Refractor Module is also capable of modeling effects such as vacuum metalizing or anti-reflection coatings on refractor surfaces and stacked materials of various indices. Photopia does not currently model scattering inside the refractor material but internal losses are accounted for via the extinction coefficient. Note, however, that if you require modeling of a refractor material that includes internal scattering such as white acrylic, then this surface can likely be modeled using the standard “transmissive” surfaces Photopia supports which utilize measured BRDF/BTDF data.