Realization and calibration of an oblique-incidence rhomb retarder of extreme retardance stability

Abstract

Based on previous theoretical studies, an oblique-incidence quarterwave phase retardation rhomb is realized and calibrated. The rhomb is made of flint glass (n = 1.7000 at 589 nm). In the wavelength interval 400–950 nm, the retardance varied between 87.98° and 88.10°. Deviation from the design retardance value of 90° resulted from the formation of surface layers on the rhomb faces, polishing effects and internal stresses. The retardance could be adjusted to ∼90° by a small variation in the external angle of incidence. Achromaticity of this type of rhombs implies using high refractive index glasses (n > 1.6).