Laser radar for remote detection of oil spills

Abstract

A laser radar system that is capable of remotely detecting oil spills, in the daytime and at night, in sea water has been developed. The system employs the second harmonic and fourth harmonic of a repetitively Q-switched Nd:YAG laser as the light sources and a gated optical multichannel analyzer as a high speed detection device. The results show that the comparison of backscattering spectra obtained from different samples enables us to detect and characterize oil spills in sea water. Raman backscattering and backscattered fluorescence of kerosene, light oil, heavy oil, and sea water have been investigated both in the laboratory and in the harbor of Seto Inland Sea of Japan by using the laser radar system described above. The SNR of this laser radar system for the detection of Raman backscattering of kerosene and fluorescence of oil is also described.

Raman spectrometry

“…Further detections of 103 ppm concentrations of S02 at 300-m distance (39) and the rotational spectrum of C02 ( 40) have been reported. An illustration of the potential of Raman-lidar is provided by humidity sounding of the atmosphere (41) where a vertical resolution of 30 m has been achieved with an accuracy of 15% at a height of 1000 m. The use of such systems for the detection and characterization of oil spills at sea has been demonstrated (42) and a Raman technique for the remote sensing of subsurface water temperature is being developed (43). Rapid Raman techniques find valuable application in kinetics measurements and in the study of transient species (44).…”

Spectrometric fluorescence and Raman lidar: absolute calibration of aerosol fluorescence spectra and fluorescence correction of humidity measurements

“…Fluorescence lidars have long been an integral instrument in the environmental sciences. For example, they are of great importance in monitoring the condition of vegetation, buildings, and water bodies (e.g., Johansson et al, 1996;Raimondi et al, 1998;Saito et al, 2016) or in hazard detection (e.g., Sato et al, 1978;Bobrovnikov and Gorlov, 2011;Li et al, 2019). In the study of atmospheric aerosol, on the other hand, fluorescence has long played a minor role compared to Raman scattering and has been treated almost in a stepmotherly way, despite its potential to add a new dimension to the aerosol information space.…”

Spectrometric fluorescence and Raman lidar: Absolute calibration of aerosol fluorescence spectra and fluorescence correction of humidity measurements

“…Fluorescence lidars have long been an integral instrument in the environmental sciences. For example, they are of great importance in monitoring the condition of vegetation, buildings, and water bodies (e.g., Johansson et al, 1996;Raimondi et al, 1998;Saito et al, 2016), or in hazard detection (e.g., Sato et al, 1978;Bobrovnikov and Gorlov, 2011;Li et al, 2019). In the study of atmospheric aerosol, on the other hand, fluorescence has long played a minor role compared to Raman scattering and has been treated almost stepmotherly, despite its potential to add a new dimension to the aerosol information space.…”