Use of point spread and beam spread functions for analysis of imaging systems in water
- 1 August 1977
- journal article
- Published by Optica Publishing Group in Journal of the Optical Society of America
- Vol. 67 (8), 1105-1117
- https://doi.org/10.1364/josa.67.001105
Abstract
An accurate method of analysis of underwater imaging systems using optical spread functions and their transforms, the modulation transfer functions, is presented. The overall system spread function is obtained from the water spread functions and the spread functions of the system components. The water point spread and beam spread functions are defined, and measurements of these are presented for clear coastal water for distances up to nine attenuation lengths. Relationships between the spread functions and their dependence on range are also given. In addition, their relationships to the conventional optical oceangraphic parameters of beam attenuation, absorption, and scattering are described. Combined optics-water spread functions and their transforms are developed for illuminator and receiver geometries typically used in underwater imaging. These are then used to determine the system (optics plus water) response to the target reflectance. An analytic technique for accurate computation of backscatter signals is developed. Computed and measured signals compare favorably. It is concluded that the use of spread functions is a convenient and viable technique for analytic computation of underwater images.Keywords
This publication has 4 references indexed in Scilit:
- Multiple Scattering Calculations of Light Propagation in Ocean WaterApplied Optics, 1973
- Application of Fourier Techniques to Underwater Image Transmission: A Test of the Linear-Invariant Hypothesis*Journal of the Optical Society of America, 1972
- Loss of Resolution in Water as a Result of Multiple Small-Angle ScatteringJournal of the Optical Society of America, 1969
- Light in the Sea*Journal of the Optical Society of America, 1963