Instead of a metallic coating, a dichroic optical coating may be used. Depending on its characteristics (thin-film interference), the ratio of reflection to transmission will vary as a function of the wavelength of the incident light.OverviewA beam splitter or beamsplitter is an that splits a beam of into a transmitted and a reflected beam. It is a crucial part of many optical experimental and measurement systems, such as In its most common form, a cube, a beam splitter is made from two triangular glass which are glued together at their base using polyester,, or urethane-based adhesives. (Before these synthetic,.