The WPQ-2660-2M from OptoSigma Corporation is a Half Wave Zero-Order quartz waveplate that operates at 266 nm. It has a theoretical retardation of 133 nm and a retardation tolerance of less than λ/50. This waveplate has a clear aperture of 17 x 17 mm with a thickness of 5 to 6.3 mm. The waveplate has a surface quality of 20-10 scratch dig.
