Laser Surface Fluorosensor for Monitoring Phytoplankton

摘要

A free path surface fluorosensor laser system, capable of giving a real time indication of the presence of phytoplankton at or near the sea surface, is reported. The system utilises an Argon ion laser operating at 488 nm, the output beam of which is amplitude modulated, expanded and directed onto the water surface. The resulting phytoplankton fluorescence is collected via a simple telescope and filter arrangement and then passed to a phase sensitive detection system. Initial tests using a single phytoplankton species (Thalassiosira pseudonana) carried out in the laboratory have shown that the system is able to detect phytoplankton (500k cells/ml) at ranges up to 15m.