Achromatic retarders are key components used in optical system design. Various researchers have proposed different combinations of quarter-wave plates that exhibit good achromatic behavior over a broad wavelength range. One of the pioneering works in this area was that of Pancharatnam, who proposed a combination of three wave plates where the fast axis of the first and the last wave plates were parallel, and both quarter-wave and half-wave achromatic retarders were obtained by proper orientation of the central wave plate. In this paper the superachromatic behavior of a quarter-wave retardation system, consisting of three wave plates, is studied in the spectral range from 500-700 nm (i.e., the visible range), centered around the design wavelength of 575 nm. It will be shown that, if the second and third wave plates of the proposed configuration are oriented at 67.5 degrees and 90 degrees, respectively, a retardation variation of as low as +/- 0.13 degrees is observed over the said visible range, indicating the superachromatic nature of the proposed system. (C) 2021 Optical Society of America
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