Degree of polarization in laser speckles from turbid media: implications in tissue optics.
The degree of polarization (DOP) of laser-speckle fields, where the speckles were generated by a polarized laser beam incident upon two kinds of samples: ground glass and wax, was investigated within a single coherence area as well as over multiple coherence areas. For the surface-scattering ground glass, the incident polarization state was preserved in the speckle field, and hence the DOP remained at unity regardless of the area of detection. For the volume-scattering wax, the polarization states varied with positions in the field, and consequently the DOP depended on the area of detection: the DOP decreased with an increasing area of detection, and only when the area was much smaller than the coherence area would the DOP approach unity. A numerical simulation explained the experimental observation. These results are important for the understanding of polarization phenomena in turbid media such as biological tissue.
Li
Jun
J
Texas A&M University, Optical Imaging Laboratory, Biomedical Engineering Program, 3120 TAMU, College Station, Texas 77843-3120, USA.
Yao
Gang
G
Wang
Lihong V
LV
D055592:Biophysical Phenomena; D001703:Biophysics; D007834:Lasers; D008962:Models, Theoretical; D009391:Nephelometry and Turbidimetry; D055095:Optics and Photonics; D012542:Scattering, Radiation