The photon-scattering imaging data of Liposyn II intravenous emulsion solution samples of different
concentrations and different thicknesses is reported and analyzed. The scattering Mueller matrix
element m11 data shows that the maximum number of multi-photon scatterings is an increasing
function of concentration and sample thickness.
Analytic formulas are derived for the Jones matrix and the Mueller matrix for dipole scattering by an ellipsoid and by a
system of ellipsoids with totally random orientation. The scattering Mueller matrix by an ellipsoid as a function of
ellipsoid orientation was simulated and showed complicated structure. The average Jones matrix for an ensemble of
randomly oriented ellipsoids is proportional to the Jones matrix for a sphere. The averaging of the Mueller matrices
washes away all the complicated structures and reduces to a simple Mueller matrix only a little more complicated than
that for a sphere. The polarization of the dipole scattering by such ensemble depends on the scattering angle and the
polarizability ratio β of a single ellipsoid. Scattering in the direction perpendicular to the incident direction shows the
largest effects on both linear polarization and depolarization, although it has minimal intensity. More anisotropy (larger
β) of scattering particles results in larger depolarization.
Tissue is optically anisotropic and highly photon-scattering medium. It has long been treated as optically
diffusive medium in bio-medical applications. The diffusion equation of isotropic photon-density wave (PDW)
was widely applied to interpret the data of reflectance spectroscopy and biomedical imaging experiments. In
our recent transmission Stokes imaging experiment of the rat liver samples, the Mueller matrix elements were
measured and analyzed theoretically. The measured data of depolarization constant has shown that the optical
property is not perfectly diffusive. Based upon our recently developed theoretical model of anisotropic and
highly photon-scattering medium, the simulated results of anisotropy, photon-scattering and depolarization
property for the reflectance/backscattering experiment are reported.
Tissues are optically anisotropic and highly photon scattering media. By using a simple ellipsoid model of bio-molecules
with anisotropic distribution and using an effective mean-field theory, the principal anisotropic index of refraction nj(ω) and absorption extinction coefficient Kaj(ω), (j = x,y,z) are derived. The scattering extinction coefficient Ksj is calculated
from our scattering depolarization theory of highly scattering bio-medium. The criterion of optical isotropy and
anisotropy of a bio-medium is derived. The non-vanishing ▵n, ▵Ka and ▵Ks exist for medium with anisotropic molecules only. ▵Ks/<Ks> is larger for medium with higher density.
Polarimetric imaging of Stokes vector (I, Q, U, V) can provide 4 independent signatures showing the linear
and circular polarizations of biological tissues and cells. Using a recently developed Stokes digital imaging
system, we measured the Stokes vector images of tissue samples from sections of rat livers containing normal
portions and hematomas. The derived Mueller matrix elements can quantitatively provide multi-signature
data of the bio-sample. This polarimetric optical technology is a new option of biosensing technology to
inspect the structures of tissue samples, particularly for discriminating tumor and non-tumor biopsy. This
technology is useful for critical disease discrimination and medical diagnostics applications.
The bio-media are made of anisotropic molecules. Using a simple ellipsoid model, the scattering of bio-medium with
anisotropic bio-molecule is investigated theoretically. The scattering fields and Mueller matrices are derived from
fundamental electromagnetism theory. The bio-medium is modeled as a system of non-correlated anisotropic molecules.
Based upon a statistical model of anisotropic distribution, the scattering Mueller matrix is derived. The single and double
photon scattering models are investigated. Double scattering is more important for high density scattering medium. For
incident light with pure polarization, such as linear and circular polarizations, the results of molecular shape-dependent
differential and total scattering cross-sections are reported. This theory can provide a simulation tool for investigating the
scattering and polarization/depolarization effect in the highly scattering bio-medium.
An isotropic medium can consist of a system of spherical particles as well as anisotropic particles with perfectly random
orientation. Even though the scattering particle is spherical, the anisotropic geometry of the incident and scattering
direction can cause polarization in the scattering beam. For a system of randomly oriented anisotropic particles, both
polarization and depolarization exist. This work reports the polarization and depolarization of dipole scattering for such
an overall isotropic system whose anisotropic particles are ellipsoids by using both the Jones matrix and Mueller matrix
Light depolarization due to multiple scattering in tissue is an interesting bio-medical issue. The bio-tissue is made of
anisotropic molecules. Using a simple ellipsoid model, the polarization property of single anisotropic bio-molecule has
been investigated theoretically. We extend this theory to a bio-tissue that is modeled as a system of non-correlated
anisotropic molecules. Based upon a statistical model of anisotropic distribution, the scattering depolarization effects are
investigated. The simulated molecular orientation-dependent single scattering depolarization Ds (1) and the double scattering depolarization Ds (2) are reported. Ds (2) contribution is more important for high density scattering medium. This theory has provided a simulation tool for investigating the depolarization effect in the highly scattering bio-medium.
The polarization of diffraction by a sawtooth reflection grating has been previously measured with fixed in and out
directions while the grating was turned. The measured polarization and depolarization can provide more information
about grating diffraction. The efficiency and polarization of diffraction by the two sawtooth facets are simulated based
on the vector formulation of the Kirchhoff diffraction theory. The simulated diffraction pattern for the two-facet model
agrees well with the measured one especially near the two specular peaks. The simulated diffraction polarization agrees
with the measured one for diffraction orders with efficiency greater than 1%. For diffraction orders with efficiency <
1%, other diffraction mechanisms also come into place.
Diffraction angles, diffraction efficiency and polarization of diffraction by a reflection grating were measured by a null ellipsometer at a wavelength of 632.8 nm. The grating is too rough to be measured by a stylus profiler or an interferometric profiler. The measured diffraction angles follow the grating equation very well and can be used to predict the period of a grating. The efficiency for different diffraction orders can be used to predict the surface profile using appropriate models. For a reflection grating with 150 grooves/mm, the measured ψ ranges from 16 to 84o and ▵ from 96 to 361o. This wide range of polarization is rarely seen for other kinds of samples. Depolarization is small when the efficiency is high and efficiency is small when the depolarization is large.
Polarization of both Reflection and transmission scatterings by a rough plane surface of a glass hemisphere with a smooth spherical surface were measured. Null ellipsometry was used to measure the ellipsometric parameters and depolarization. Linear polarization, circular polarization, and principal Mueller matrix were obtained from the above measured quantities. Scattering was measured at fixed incident and detection directions, and variable sample orientation. The scattering and its polarization and depolarization are symmetric with the off-specular angle (OSA). The measured linear polarization increases with increasing OSA, and may change sign for large OSA. Reflection scattering shows more depolarization than the transmission scattering and so do the deviations from the specular values for all parameters.
The full polarization property of a holographic volume grating sample is investigated both theoretically and experimentally. There exists strong interaction between the transmitted and diffracted beams due to the grating diffraction of orders m=-1 and 1. Based upon a volume grating mode, the diffracted fields and Mueller matrices of the interacting transmitted and diffracted beams were first analytically derived. The formalism is derived for the general case that the diffraction beam and the grating wave-vector are not in the plane of incidence, where s-waves and p-waves are not de-coupled. For a single-hologram grating sample, the Mueller matrix is measured at wavelength 632.8 nm and in good agreement with the theory. The result demonstrates a correlation between the diffraction strength and the polarization properties of the volume holographic grating. The derived algorithm has provided a simulation analysis tool for the engineering device design of real holographic beam combiner/splitter (HBCS) devices.
Principal Mueller matrices of scattering by a rough paint surface are measured. Null ellipsometry is used to measure the ellipsometric parameters and depolarization of scattering with small depolarization (< 0.2). Linear polarization, circular polarization, and principal Mueller matrix are obtained from the above measured quantities. Stokes method is used to measure the principle Mueller matrix for scattering with large depolarization (> 0.2), and all other polarization characteristics are derived from the principal Mueller matrix. Scattering is measured at fixed angle (2K) between the incident and detection directions, and variable sample orientation. The scattering and its polarization characteristics are symmetric with the off-specular angle (OSA). The measured linear polarization increases with increasing OSA, and may change sign for the cases of small K. The measured depolarization increases with increasing OSA more than linearly, and is larger for smaller K.
Ellipsometric parameters, depolarization and directional reflectance of reflection and scattering by a rough stainless steel surface are measured. Linear and circular polarizations, and principal Mueller matrix can be obtained from the above quantities. Measurements were made at fixed incident and detection directions and variable sample's orientation. For one-dimensional rough surfaces, it was found that depolarization and circular polarization increase with the off-specular angle of scattering while linear polarization does the opposite. Measurements were also made for specular direction. The effective refractive index, extinction coefficient and rms roughness for the rough sample were derived from these data.
Based upon known surface optical properties, we develop a model to calculate and analyze the linear and circular polarization signatures for targets of known geometric shapes. The linear and circular polarization radiation (emission and reflection) generated from the target surfaces are studied in two model surface structures: metallic and non-metallic substrates with/without dielectric coating. Infrared I, Q, U, and V images of a model cylindrical target with these surfaces are calculated. This paper shows that dielectric coating enhances the power of generating circular polarization radiation. In addition to the linear polarization, circular polarization imaging attributable to target surface reflection is also shown to be feasible for practical application.