Abstract
Digital Holography is a technique which provides a measurement of the complex field reflecting from a coherently illuminated object. When the measurement is performed with two carefully chosen wavelengths a phase difference map can be created providing a three dimensional map of the object. We present results from a laboratory experiment where the surface contours of coral are measured in seawater. Contour maps with step sizes on the order of 0.1 mm can easily be obtained. We propose that this technique be used to remotely monitor the growth of coral in an effort to quantify the health of coral beds. The technique is effective from space, aircraft, ships, buoys or rigid platforms such as a pier. In the last few years we have been successfully using this technique to measure objects through very turbulent atmosphere at ranges of up to 700 meters and we are now applying the concept to shoreline applications.