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LIDAR Light Detection and Ranging

LIDAR Light Detection and Ranging. Kate Whalen PHY 3903 Nov. 25, 2005. Outline. Some applications How lidar works Examples of current lidar projects Purple Crow Lidar Dalhousie Raman Lidar. Applications. Distance measurements Atmospheric composition Weather Mapping

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LIDAR Light Detection and Ranging

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  1. LIDARLight Detection and Ranging Kate Whalen PHY 3903 Nov. 25, 2005

  2. Outline • Some applications • How lidar works • Examples of current lidar projects • Purple Crow Lidar • Dalhousie Raman Lidar

  3. Applications • Distance measurements • Atmospheric composition • Weather • Mapping • Speed measurements

  4. Lidar Basics • Active remote sensing • Light is emitted, scattered, and detected. • Since we know the speed of light, we can measure the distance travelled!

  5. Details • 3 main parts • Transmitter • Example: Pulsed Nd:YAG laser (532 nm) • Low beam divergence • Narrow spectral width • Receiver • Optical telescope • Detector • PMT • Chopper • Eliminates near-field returns

  6. Purple Crow Lidar (UWO) • Detector consists of a 2.65 m mercury mirror, rotating at 10 rpm • Parabolic mirror • 532 nm Nd:YAG laser used for Rayleigh scattering • Elastic scattering at 30-90 km • Obtain T(z) from density profile • Assumptions • Hydrostatic equilibrium • Ideal gas

  7. PCL Projects

  8. Dalhousie Raman Lidar • CABOT Observatory • Canadian Atmosphere-Biosphere Observations Trailer • 607 nm Nd:YAG laser • Raman scattering • Inelastic scattering (change in rotational or vibrational energy) • Frequency of scattered photon depends on temperature, type of molecule • Investigates atmospheric aerosols & clouds • Transboundary pollution transport

  9. CABOT Projects

  10. In Conclusion… • Lidar is an example of physics for the benefit of the planet!

  11. References • Thanks to Dr. Bob Sica and the PCL group at UWO! • Argall, P. S. & R. J. Sica, Lidar (Laser Radar). In The Encyclopedia of Optics, Vol. 2, Ed. T. G. Brown et al., Wiley-VCH, Weinheim, 2005. • Duck, T. J. et al., Lidar measurements of atmospheres. Physics in Canada 61 (5) 247-252, 2005. • Sica, R. J. et al., Lidar measurements taken with a large-aperture liquid mirror. 1. Rayleigh-scatter system. Applied Optics 34 (30) 6925-6936, 1995. • Environment Canada: Air Quality Processes Research Division [Online]. http://www.msc.ec.gc.ca/arqp/index_e.cfm[Nov. 24, 2005]. • Purple Crow Lidar [Online]. http://pcl.physics.uwo.ca/[Nov. 24, 2005]. • REALM: Regional East Atmospheric Lidar Mesonet [Online]. http://alg.umbc.edu/REALM/[Nov. 24, 2005]. • The Atmospheric Optics Laboratory [Online]. http://aolab.phys.dal.ca [Nov. 24, 2005].

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