Polarization-difference imaging (PDI) was recently presented by us as
a method of imaging through scattering media [Opt. Lett. 20, 608 (1995
)]. Here, PDI is compared with conventional, polarization-blind imagin
g systems under a variety of conditions not previously studied. Throug
h visual and numerical comparison of polarization-difference and polar
ization-sum images of metallic targets suspended in scattering media,
target features initially visible in both types of images are shown to
disappear in polarization-sum images as the scatterer concentration i
s increased, whereas these features remain visible in polarization-dif
ference images. Target features producing an observed degree of linear
polarization of less than 1% are visible in polarization-difference i
mages. The ability of PDI to suppress partially polarized background v
ariations selectively is demonstrated, and discrimination of target fe
atures on the basis of polarization information is discussed. Our resu
lts show that, when compared with conventional imaging, PDI yields a f
actor of 2-3 increase in the distance at which certain target features
can be detected. (C) 1996 Optical Society of America