BK7 pentaprism GCL-0302 series

A Penta prisms is a five-side prisms, featuring two important properties. Firstly, the images is neither inverted nor reversed while it is deviated by 90 degree. Secondly, it is a constant deflection device, i.e., all the transmitted rays are exactly deflected by 90 degree. Slight movement of the prisms does not affect the right deflected angle. This feature makes the prisms useful in rangefinder. It is also used in viewfinders of single reflex cameras. The reflecting surfaces are enhanced aluminum-coated with black paint overcoat for protection. • Dimension Tolerance: ±0.1 • Flatness: λ/4 at reflection surface λ/2 at transmission surface • Surface Quality: 60-40 scratch-dig • Clear Aperture: 90% • Coatings: Reflecting surfaces are aluminized with black paint. Entrance and exit surfaces are 1/4 wave MgF2 coating at 550nm for 0˚ angle of incidence.