The Theory of Laser Bathymetry Using the Effect of Multiple Reflection of a Light Pulse from the Seafloor

Abstract

This work deals with the problem of using lidar for measuring the extremely small depths at which the difference between the times of arrival of the echo signals from the sea surface and the seafloor becomes smaller than the sounding-pulse duration. To solve this problem, we propose to use the effect of multiple reflection of light from the seafloor, which leads to the appearance of additional echo signals with delay times exceeding the time of the double light-pulse transmission through the water layer. It is shown that the doubly reflected signal can actually be used for decreasing the minimum measured sea depth by a factor of about 2.5 with unchanged sounding-pulse duration.