Remote sensing with intense filaments enhanced by adaptive optics

• Published in: Applied physics. B, Lasers and optics Lasers and optics, 2009-11, Vol.97 (3), p.701-713
• Main Authors: Daigle, J.-F., Kamali, Y., Châteauneuf, M., Tremblay, G., Théberge, F., Dubois, J., Roy, G., Chin, S. L.
• Format: Article
• Language: English
• Subjects: Adaptive optics; Atmospheric optics; Beams (radiation); Biological and medical applications; Clouds; Engineering; Exact sciences and technology; Filaments; Focusing; Fundamental areas of phenomenology (including applications); Laser spectroscopy; Lasers; Mathematical analysis; Optical Devices; Optics; Photonics; Physical Chemistry; Physics; Physics and Astronomy; Quantum Optics; Remote sensing; Remote sensing; lidar and adaptive systems; Wave fronts
• ISSN: 0946-2171; 1432-0649
• DOI: 10.1007/s00340-009-3713-7

A method involving a closed loop adaptive optic system is investigated as a tool to significantly enhance the collected optical emissions, for remote sensing applications involving ultrafast laser filamentation. The technique combines beam expansion and geometrical focusing, assisted by an adaptive optics system to correct the wavefront aberrations. Targets, such as a gaseous mixture of air and hydrocarbons, solid lead and airborne clouds of contaminated aqueous aerosols, were remotely probed with filaments generated at distances up to 118 m after the focusing beam expander. The integrated backscattered signals collected by the detection system (15–28 m from the filaments) were increased up to a factor of 7, for atmospheric N 2 and solid lead, when the wavefronts were corrected by the adaptive optic system. Moreover, an extrapolation based on a simplified version of the LIDAR equation showed that the adaptive optic system improved the detection distance for N 2 molecular fluorescence, from 45 m for uncorrected wavefronts to 125 m for corrected.