Phenomenological and mathematical analyses of oblique incidence in tot
al-internal-reflection phase retarders and the procedure for construct
ing extremely achromatic quarter-wave retarders are presented. It is s
hown that the retardance can assume the same value twice at two defini
te spectral lines. As an example, a quarter-wave phase retarder is des
cribed that introduces a retardance of exactly 90 degrees at two He-Ne
laser Lines of 632.8 and 1150 nm with a maximum deviation of 0.007 de
grees for other wavelengths between these two Lines. This application
is advantageous in conjunction with two-line and multiline lasers wher
e the radiation is usually pumped in a state of circular polarization.
(C) 1997 Optical Society of America.