There are many types of optical prisms,such as wedge prisms,righe angle prism,rhombohedral prism,dispersing prism etc.each having a particular geometry to achieve the reflections necessary to perform a specific imaging task. Rectangular prisms(right angle prism) are used to deflect a beam of light through 90 or 180 degrees. This can be used as component to create various optical devices. BK-7 can be used for a range between the visible and infrared light.Fused-silica can be used for a range between ultraviolet and infrared light. China star optics offers a wide range of different materials and different degrees of precision prisms. Specification of our right angle prisms/rectangular prisms as follow: *Material: BK7 glass or UV grade fused silica *Dimension Tolerances: +/-0.1mm *Angle Tolerance: +/-3 'or 30†*Clear Aperture: 90% *Surface Quality:60/40 or 20/10 *Surface Flatness: lambda/8 or lambda/4 at 633nm *Chamfer:0.3+/-0.1mm *Coating Optional