Optical Vortices through Laser Beam Engineering for Remote Sensing Applications

Because it can be used in situ without the need for any sample preparation, optical emission spectroscopy techniques are favored as a spectroscopic tool to remotely detect and interrogate nuclear materials. While they have been successful in the lab, field tests results are lacking because high laser intensity is needed at standoff distances. Furthermore, the return signal from optical interrogation drops drastically as 1/r2 with r being the distance from the detector to the sample. Our proposed technology applies a multimodal optical emission spectroscopy – utilizing both laser- induced breakdown spectroscopy (LIBS) and Raman spectroscopy – to provide both atomic and molecular measurements of the REE in both solid and aqueous media. This can be performed on site and in-line without any sample preparation. A multivariate analysis of the measured spectrum will enable the user to classify different types of coal and its by-products, and may provide sensitivity down to the sub- ppm level. For long range detection, optical vortices have shown remarkably robust propagation through turbulent atmosphere. In this work, we will conduct proof-of-concept experiments to demonstrate the advantages of nanosecond optical vortices for laser-induced breakdown spectroscopy where the characteristic emission spectrum may be enhanced at the detector. The proposed technology using high energy nanosecond optical vortices will be able to detect a wide range of materials, such as explosives, organic, radiological and special nuclear materials at standoff distances. Due to its long-range capability, this sensor can also be used for weather monitoring LIDAR, remote sensing, optical communication and material processing.