Bevels are clean ground edges used to prevent edge chips or simply as protective chamfers. Our bevels are defined as maximum face widths at 45°, with a standard tolerance of ±15°. For micro optics, we do not bevel the edges (since the attempt will likely cause chips). Also, we do not bevel the edges for small radii meeting the diameter edge at large angles. If the diameter = (0.85 x radius of curvature), then no bevel is used. The actual clear aperture (CA) value used will typically be smaller than that defined by the bevels with a maximum possible CA calculated as follows: