We present both experimental measurements and Monte-Carlo-based simulations of the diffusely backscattered intensity patterns that arise from illuminating a turbid medium with a polarized laser beam. It is rigorously shown that, because of axial symmetry of the system, only seven elements of the effective backscattering Mueller matrix are independent. A new numerical method that allows simultaneous calculation of all 16 elements of the two-dimensional Mueller matrix is used. To validate our method we compared calculations to measurements from a turbid medium that consisted of polystyrene spheres of different sizes and concentrations in deionized water. The experimental and numerical results are in excellent agreement.

We present both experimental and Monte Carlo -based simulation results for the diffusely backscattered intensity patterns that arise from illumination of a turbid medium with a polarized laser beam. A numerical method that allows the calculation of all 16 elements of the two-dimensional Muller matrix is used; moreover, it is shown that only seven matrix elements are independent. To validate our method, we compared our simulations with experimental measurements, using a turbid medium consisting of 2.02-mm-diameter polystyrene spheres suspended in deionized water. By varying the incident polarization and the analyzer optics for the experimental measurements, we obtained the diffuse backscattering Mueller matrix elements. The experimental and the numerical results are in good agreement. © 1998 Optical Society of America OCIS codes: 290.1350, 290.7050, 260.5430. A few recent studies demonstrated that one can measure information on the properties of a turbid medium by shining a polarized laser beam upon a sample and then analyzing the state of polarization of the diffusely backscattered light. The investigated applications of this technique include measurements for the average particle size, the scattering coeff icient, and the anisotropy factor of particle suspensions 1 as well as cloud diagnostics, 2,3 the study of biological material, 4 -6 and the measurement of average photon path lengths. 7To achieve full experimental characterization of the optical properties of the sample under investigation, Hielscher et al.6 used a Stokes vector-Mueller matrix approach to polarized light scattering. They generalized the concept of the effective Mueller matrix 8 and measured the two-dimensional Mueller matrix of the backscattered light from a turbid medium. In a recent theoretical paper Ambirajan and Look 9 used a Monte Carlo technique to study the multiple scattering of a polarized light beam from a plane-parallel medium. They investigated the degree of polarization of the diffuse light when the incident beam was right circularly polarized.In this Letter our theoretical analysis is based on the assumption that the scattering of light is incoherent. The incoming narrow laser beam propagates downward along the z axis and scatters from the medium located in the lower half-space. Let P 0 be the Stokes vector that corresponds to the power of the incident laser beam with respect to the x z reference plane and let I bs ͑r, f͒ be the Stokes vector that describes the radiance at the detector [i.e., at the point ͑r, f͒ on the surface of the scattering medium]. Then, I bs ͑r, f͒ m s 2 S͑r, f; m s , m T ͒P 0 , where m s and m T are the scattering and the extinction coefficients, respectively, and S can be seen as the effective backscattering Mueller matrix. If the scattering medium is homogeneous, the effective Mueller matrix takes the formwherev is the single-scattering albedo and r s is the scaled radial distance. R is the standard 4 3 4 matrix that rotates the reference plane. 10The term L n in the above sum corresponds to backsc...

Anisotropy in the polarization of the backscattered light from a polarized laser beam incident upon a scattering medium has been observed experimentally. When the beam is viewed through an oriented polarizer, characteristic patterns in the backscattered light are observed. We present here a simple explanation of these patterns, using the theory of incoherent scattering of light by spheres. It appears that the major contribution to the observed patterns comes from the double scattering of light.

We present a theoretical analysis on use of polarized light in the detection of a model target in a scattering and absorbing medium similar to seawater. Monte Carlo numerical simulations are used in the calculation of the effective Mueller matrix which describes the scattering process. A target in the shape of a disk is divided into three regions, each of which has the same albedo but different reduced Mueller matrices. Contrast between various parts of the target and background is analyzed in the images created by ordinary radiance, by various elements of the Mueller matrix, and by certain suitable combinations of these elements. It is shown that the application of polarized light has distinct advantages in target detection and characterization when compared with use of unpolarized light.

In our recent Letter,(1) several typographical errors were present. On p. 487, in Fig. 2, the equations for the following Mueller matrix elements should read as S(14) = (RO - LO), S(22) = (HH + VV) - (HV + VH), S(23) = (PH + MV) - (PV + MH), S(24) = (RH + LV) - (RV + LH), S(32) = (HP + VM) - (HM + VP), S(33) = (PP + MM) - (PM + MP), S(34) = (RP + LM) - (RM + LP), S(41) = (OR + OL), S(42) = (HR + VL) - (HL + VR), S(43) = (PR + ML) - (PL + MR), and S(44) = (RR + LL) - (RL + LR). Also on p. 487, in the left-hand column, line 10 from the top should read as follows: mfp? = 1/[mua + mus(1 - g)], was 0.957 cm.