V. Pollak

Bio: V. Pollak is an academic researcher from University of Saskatchewan. The author has contributed to research in topics: Linear approximation. The author has an hindex of 1, co-authored 2 publications receiving 13 citations.

The Surface Intensity of Fluorescence Excited in a Turbid Medium

Abstract: Based upon the simplified theory of Kubelka and Munk a quantitative relationship for the fluorescent intensity, observed from either side of a plane parallel sheet of turbid material, has been derived. The fluorescing substance is assumed to be uniformly distributed throughout the bulk of the medium. The results obtained show that fluorescence measurements from either side have good linearity over a very wide range of concentrations of fluorescing substance. Measurements from either side are very nearly equivalent in this regard. As expected, the fluorescent intensity observed at the illuminated surface is higher than that observed at the exit plane. The results are intended mainly for use in the quantitative analysis of fluorescent substances dispersed in a turbid medium. Typical applications are thin-layer chromatography and electrophoresis.

An Approximate Linear Relationship for the Optical Response of Turbid Media

Abstract: The optical response of a homogeneous turbid medium is often expressed analytically with the aid of the simplified theory of Kubelka and Munk. The equations derived from this theory yield the response A as an explicit function of absorption Kand scatter S. In practice, however, an inverted form is frequently needed, which would display absorption as an explicit function of A and S. No closed-form rigorous inversion of the response function A(S, K) is available, though approximate solutions exist. All direct inversions, analytical or empirical, are highly non-linear, even though for measurement and instrumentation purposes a linear characteristic is highly desirable. This paper shows that this can be achieved by using a logarithmic transform for the transmittance and a reciprocal one for the reflectance mode. Graphs are given for the coefficients of the linear approximation applicable over a wide range of the parameters S and K ; also shown is the mean error incurred in this range; it is nowhere in excess ...

Progress in Inverse Optical Problems

Abstract: The direct problem in optical physics is to predict the emission or propagation of radiation on the basis of a known constitution of sources or scatterers. The inverse or indirect problem is to deduce features of sources or scattering objects from the emitted or scattered radiation that has propagated to a detector. A small selection out of the large number of topics pertinent to the inverse problem in optical physics was examined in a previous volume in this series, entitled Inverse Source Problems in Optics [1.1], namely the phase retrieval problems, the question of uniqueness in the reconstruction of scatterers, the reconstruction of subwavelength sources, the connection between coherence and radiometric quantities, and the determination of statistical features of random phase screens from scattering data. A number of topics not covered by [1.1] are discussed in the present volume, Inverse Scattering Problems in Optics: deterministic and stochastic structural determinations using the theory of entire functions, the photon-counting statistics of optical scintillations with emphasis on the recently discovered K distributions, the connection between the raw data of photodetection and the properties of the received radiation field (the inverse detector problem), the ubiquitous question of the numerical instability of inverse problems, the multiangular absorption approach to combustion diagnostics, and polarization effects in inverse electromagnetic scattering.