Our 50/50 Polka Dot Beamsplitters provide two unique advantages over traditional dielectric beam splitters: they are neutral over the wavelength range of the fused silica substrate and the aluminum coating, and they are not sensitive to angle of incidence changes.

These beamsplitters are coated with aluminum and SiO protective overcoat in a polka dot pattern. The pattern is a series of aluminum dots, 2.5 mm in diameter, separated by a 3.2 mm center-to-center distance.

Optimized for white light illumination applications, the smallest beam diameter suitable for a 50/50 split is 0.37 inches (9.5 mm). For beams larger than this, 50% of an incident beam hits the coated area, independent of the angle of incidence, and is reflected. The other 50% of the incident beam hits the uncoated fused silica. The reflectance off the uncoated area is angle- and polarization-sensitive, but this is a minor effect (except at very high angles of incidence). For angles up to 45°, specified performance can be expected.

These beamsplitters should not be used in the focal plane of an imaging system.