Intensity fluctuations in forward scattering and temporal coherence.
The problem of forward scattering by a nonergodic system of identical particles is considered. The analysis of statistical characteristics of intensity fluctuations arising as a result of finite observation time shows that the mean dispersion of intensity fluctuations can be expressed as a function of the wavelength, diffusion coefficient, scattering angle, and observation time. The relation between the temporal correlation function of the scattered radiation and its second-order intensity moments is established. Quantitative estimates of the effect with the infrared laser beam propagating through fog give results comparable to the dispersion due to refractive index fluctuations in a pure atmosphere (Tatarskii).
Measurement of temporal coherence loss in laser light scattered from simulated coastal waters
Different techniques of measuring the coherence length of a scattered laser signal propagating through water are reviewed. A Michelson interferometer experiment was used to measure the coherence length of an argon-ion laser both in air and scattered in water. It was shown in this experiment that light scattered through water experiences a definite, measurable loss in coherence of /spl sim/10 cm. The Michelson experiment measured the total coherence loss due to all spectral broadening mechanisms present. A heterodyne experiment was used to measure the coherence loss due to Doppler broadening of an HeNe laser scattered in water. A decrease in the coherence length was observed as more light was scattered. The coherence length of the HeNe laser in air was measured with a Michelson interferometer.<<ETX>>
The Form of the General Unimodular Analytic Signal
Finding the most general unimodular analytic signal is shown to be equivalent to solving a singular integral equation of the Carleman type. This equation is solved utilizing the properties of analytic functions.