An optical technique to improve the imaging of a target inside suspensions
of scattering particles includes the illumination of the scattering
particles with circularly polarized light. The backscattered light from
the host medium preserves the helicity of incident light, while the
backscattered light reflected from the target is predominated with light
of opposite helicity. Based on the observed helicity difference in the
emerging light that originated at the target and that backscattered from
the medium, the present optical technique improves the image contrast
using circular polarization. This approach makes use of polarization
memory which leads to the reflected light from the target accompanied by
weak diffusive backscattered light. Using the present technique, improved
imaging of the artery wall is achieved and plaque composition can be
assessed through a blood field associated with the artery. The scattering
from the particles, such as red blood cells, in the blood is reduced due
to polarization memory. The present invention can be also applied to
other biomedical application, as well as image targets through adverse
environmental conditions, such as fog, clouds, smoke, murky water, etc.