An exact analysis of the working parameters of a modified Wollaston prism i
s presented. Parameters include the output splitting angle, the retardation
, and the location of the plane of the interference fringes (plane of appar
ent splitting). Results are presented for the entire range of optical axis
inclinations and wedge angles. Approximate expressions from the literature
are evaluated. An angle of incidence that causes the plane of the interfere
nce fringes to be perpendicular to the axis of the optical system is found
for each configuration analyzed. This is then applied to the design of modi
fied Wollaston prisms for Nomarski differential interference contrast micro
scopy. (C) 1999 Optical Society of America.