Specifications:

Material: ..................................................Crystal Quartz
Dimension Tolerance: ..............................+0.0, -0.2 mm 
Wavefront Distortion: ...............<Lambda/8 @ 632.8 nm
Retardation Tolerance: ...............<Lambda/500 (typical)
Wavelength Range: ..................................240-2100 nm
Parallelism: ..............................................<1 arc second
Surface Quality: ...........................20-10 scratch and dig
AR/AR Coating:................R<0.2% at central wavelength