Achromatic waveplates are generally made of two different crystals, Quartz and Magnisum flouride, or Quartz and Sapphire. Unlike the general waveplates, which can work at only one single wavelength or two wavelengths, achromatic waveplates can work for a relatively wide range, which can be up to 400nm (for the different targeting ranges, this data may vary).
United Crystals' Achromatic Waveplates meet the following specifications:
Retardation Tolerance: <λ/100 over designed range
Surface Quality: 40/20 scratch dig
Parallelism: <1 arc min
Diameter Tolerance: +0.0/-0.1mm
Retardance: λ/2, λ/4, or specified by customer
Wavefornt Distortion: < λ/8@633nm
AR-coating: available upon request
For more information, please feel free to contact the United Crystals'
technical support team.