Achromatic Waveplate, Quarter-Wave, Polymer, 25.4 mm, 840 nm Center, 715-1000 nm

The 10RP44-3 Achromatic Quarter Wave Plate has λ/4 retardation at the 840 nm center wavelength and a ±λ/100 accuracy over the 715-1000 nm wavelength range. The standard 25.4 mm outer diameter is convenient for mounting into Newport rotary mounts. It is designed to operate with a high degree of retardation accuracy over a broad wavelength range. This 1 inch diameter true zero-order waveplate is constructed using a stack of birefringent polymer films laminated between two high-precision N-BK7 optical windows, each with a high efficiency, broadband antireflection coating. This construction ensures excellent transmitted wavefront quality, while minimizing beam deviation and surface reflection losses. The assembly is mounted in a black anodized aluminum housing for protection and ease of mounting, with the retarder fast axis marked for alignment reference. Achromatic polymer wave plates have better angular acceptance and less sensitivity to wavelength change than achromatic quartz–MgF₂ wave plates. Retardation changes by less than 1% over a ±7° incidence angle and is maintained to better than ±λ/100 over the entire bandwidth. Optical transmittance varies slightly from the precision zero-order wave plates because several polymer layers are used in each achromatic wave plate.