Optical Methods for Data Processing in Heat and Fluid Flow

Section 3 Fluorescence, Phospherence, and Liquid Crystals

9

The Application of LIF to Study the Dispersion of a Surface Film due to Wave Breaking using a Two-camera System

T Schlicke, A D Arnott, J M Buick, C A Greated, and N H Thomas

Abstract

In this Chapter we report on the application of laser induced fluorescence (LIF) to study the dispersion of a surface layer due to wave breaking. The technical aspects of the experiment are described; in particular we consider the production of a ‘wide screen’ image using an extended light sheet of length up to 2 m, and a double camera system which was used to obtain the images. The technique employed to produce surface films with a thickness of the order of a few microns is also described. Details are given of the normalization of the LIF images due to intensity variations in the light sheet and the calibration method which was applied.

9.1 Introduction

Surface films in the ocean can be formed in a number of ways ranging from the large-scale pollution which can be produced by, for example, an oil-spill; to small-scale, naturally occurring slicks (1, 2) due to biological processes. It is also possible that surface layers can be formed by marine rains containing high levels of dissolved free amino acids (1, 3), although it is unclear whether this constitutes a source or a sink for the surface film. Naturally occurring slicks are a complex mixture of the organic materials found in the ocean, such as fatty acids, esters, carbohydrates, and hydrocarbons ...