Reflection at transparent V-grooved surface

Reflection at transparent V-grooved surface was studied on the basis of geometrical analysis and ray tracing using Fresnelʹs formulas. For normally incident light, the reflectivity at the V-grooved surface of tilt angles between 0° and 30° and between 45° and 54° are approximated by the reflectivities and the squared reflectivities, respectively, at a smooth surface. For obliquely incident light, the V-grooved surface is effective to reduce the reflectivity at large angle of incidence by reducing the actual angle of striking the surface. In addition, the V-grooved surface of large tilt angle reduces the reflectivity at a small angle of incidence due to multiple reflections between adjacent opposite surfaces of the groove. The daily average reflectivity monotonically decreases with increasing tilt angle from 30° to its upper limit (59.1° for n=1.5) in the analysis. When normally incident light enters the layer and a part of it reflects at the rear surface, the escape from the upper surface can be prevented by serial total internal reflections at the upper surface of medium tilt angle (30.9°–41.0° for n=1.5).