DIAMETER: 20.00mm +/- 0.05mm
THICKNESS: 0.50mm +/- 0.05mm
PARALLELISM: 3 ARC MINUTES MAXIMUM.
FLATNESS: 10 WAVES/INCH MAXIMUM, 2 FACES.
SURFACE FINISH: 80-50 OR BETTER, 1 FACE.
FINE GROUND OTHER FACE.
MATERIAL QUALITY: OPTICAL GRADE.
CRYSTALLOGRAPHIC ORIENTATION: C-AXIS PERPENDICULAR
TO FACES, (0001) NOMINAL.