The 05RP12-28 Multiple-Order Quartz Wave Plates is a crystal quartz optic designed to differentially retard the phase of a polarized beam. With the proper phase shift, this waveplate can rotate the direction of polarization and the amount of polarization rotation is twice the amount of the waveplate rotation. This 1/2 inch (12.7 mm) diameter wave plate is 1mm thick and has λ/2 (180°) retardation. It is antireflection coated to maximize transmission at 780 nm. When using multiple-order wave plates, several items should be considered. A wave plate of practical thickness produces a multiple of λ/4 or λ/2 retardation. Higher orders cause retardation to vary dramatically with wavelength. Wave plates are sensitive to temperature changes. A typical multiple-order wave plate has a temperature coefficient of 0.0015λ/°C, compared to 0.0001λ/°C for a zero-order wave plate, so tighter temperature control will be required. Precise adjustment of retardation is possible by tilting the wave plate. Tilting about the slow axis increases retardation, while tilting about the fast axis reduces retardation.