Prisms Optical Components PARAMETER: BK7 Glass Dove Prism have an unusual and very interesting characteristic , if you look through the prism and rotate it around a longitudinal axis, the image rotates through twice the angle through which the dove prism itself rotates. For optimal peformance, use dove prisms with collimated light. Specification Material BK7 glass / Fused Silica Dimension tolerance + 0.0 / -0.2mm Deviation 3arc min. Flatness λ/2@632.8nm Clear aperture >85% Surface quality 60/40, 40/20 Bevel 0.1mm Ã?45°