Ocean Optics VI

Abstract

Although the world's oceans, seas and freshwater lakes play a dominant role in the planet's ecosystem, they are possibly the least understood of our natural habitats. The challenges facing scientists and engineers in the study of this environment are immense and unique. Not only is there a need for the creation of new techniques and for advances in classical techniques, but the associated instruments must withstand the rigours of the sea. High on the list of techniques which can be exploited are those based on optics and light. Many state-of-the-art submersible instruments employ some fundamental optical technique as the method of measurement, while optical communications and fibre systems are also major aspects of contact and control of subsea instruments. Of course, the nature, behaviour and propagation of light through water are fundamental characteristics of the oceans themselves. They are also crucial to the understanding of the marine habitat, and the preservation and utilization of this immense resource. We need to know how light propagates through water, and what affects transmission and absorption, and so on. The use of optical instrumentation in the field is increasing, and is replacing more traditional, slower and destructive techniques. Optical techniques provide rapid, precise, non-destructive, in-situ sensing and high quality measurements with reduced possibility of artefacts. A series of conferences on the general theme of underwater optics have been held under the auspices of the Institute of Physics. The most recent of these, Ocean Optics VI, was held in London on 9 October 2001. Selected papers from that meeting, representing the wide range of work currently being undertaken in underwater optics, are featured in this issue of Journal of Optics A: Pure and Applied Optics. The papers range from a demonstration of the use of optics in the measurement of the flocculation of suspended sediments to such novel techniques as holography for the in-situ measurement of plankton, and from the measurement of fundamental physical characteristics such as absorption, irradiance and sea-surface reflectance to the measurement of the chemical constituents of natural seawater. There is also a paper reflecting the large amount of work taking place in satellite image analysis. All in all, the papers included here, while not all-embracing, do demonstrate the range and depth of current research taking place in the expanding field of underwater optics. John Watson University of Aberdeen, UK Derek Pilgrim University of Plymouth, UK Guest Editors