High Precision Window Features: High Precision Dimension Control Minimal Transmitted Beam Deviation Excellent Environmental Durability Apply Any Anti-reflecting Coating Applications: Projection Optics System Imaging Optics System Optical Measurement Systems Specifications High Precision Windows Parameter Unit Material BK7 grade A optical glass or UV grade fused silica ,Ge,Si, MgF2 Diameter Tolerance mm +0.0, -0.1 Thickness Tolerance mm +/-0.2 Parallelism arc seconds 85% Coating Specified by customer