Specification of our right angle prism 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 @633nm *Chamfer:0.3+/-0.1mm *Coating Optional Rectangular prisms 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 an be used for a range between ultraviolet and infrared light. VY Optics Photoelectric Technology Co.,Ltd. offers a wide range of different materials and different degree of precision prisms.