Each total internal reflection can induce 1/8 phase shift. The Fresnel Rhombs utilize the total internal reflection to generate the desired phase retardation. For example, one Fresnel Rhomb can generate 1/4 wave retardation, and two rhombs in series can create 1/2 wave retardation. The most common materials are BK-7 glass, CaF2, fused silica and ZnSe.
United Crystals' Fresnel Rhombs meet the following specifications:
Retardation Tolerance: <2%
Surface Quality: 20/10 scratch dig
Parallelism: <1 arc min
Diameter Tolerance: +0.0/-0.1mm
Retardance: λ/2 and λ/4
AR-coating: available upon request
For more information, please feel free to contact the United Crystals'
technical support team.