Dayoptics manufactures high quality Crystal Quartz and MgF2 waveplates. Specification: Dimension Tolerance: +0.0, -0.1 Wavefront distortion: λ /8@633nm Retardation Tolerance: λ /800 -λ /500 Parallelism: <1 arc second Surface Quality: 20-10 Clear Aperture: Central 90% AR Coating: <0.2% @wavelength Standard wavelength: 266nm, 355nm,532nm, 632.8nm, 780nm,808nm, 850nm, 980nm,1064nm, 1310nm.