Pulse fluorescence LIDAR system for identification and low concentration measurements of Phaeocystis globosa cells and colonies

Abstract

A pulse fluorescent LIDAR system (pfLIDAR) for early-warning of Phaeocystis globosa cells and colonies outbreak is developed and demonstrated, which can realize species identification and low concentration measurement of Phaeocystis globosa in water areas. The system utilizes a high-power 532 nm nanosecond pulsed laser as excitation light source and a photomultiplier tube combined with a liquid crystal tunable filter as the detection setup. Measurement of Phaeocystis globosa solitary cells and colonies were performed in a water tank, simulating microalgae distributions and concentrations prior to blooms in real water areas. The concentration of Phaeocystis globosa cells or colonies can be accurately measured based on the received fluorescent echo signals. Obtained echo signals combined with spectral information can be used for species identification of high accuracy using a PCA-SVM method. The system works in staring scanning mode, and a gating technique is used to filter out scattering and background fluorescence noise in water path, which improves the SNR of detected fluorescent echo signals. Experimental demonstration results demonstrate the capability of the system for Phaeocystis globosa identification and biomass assessment, indicating a significant potential of the system for detailed monitoring in aquatic ecosystems.