The rhomb-type achromatic prism retarder utilizes the phase difference introduced at the glass–air interface, where the beam of light undergoes total internal reflection. With the proper choice of glass materials and the number of total internal reflection, it is possible to obtain a desired phase difference. The phase difference introduced is also dependent on the angle of incidence of the light beam at the glass–air interface. A small change in angle of incidence causes a considerable change in phase difference. The change in the phase difference introduced with the change in external angle of incidence of the light beam in an achromatic prism-type quarter-wave retarder is studied both theoretically and experimentally. The experimental results obtained are found to be in accordance with the theoretical results.