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Temporal and angular spreading of blue-green pulses in clouds
1US Naval Ocean Systems Center, San Diego, California 92152, USA.
Applied Optics
|April 15, 2010
Summary
Researchers measured blue-green laser pulse propagation through clouds, simulating satellite communications. They found pulse stretching up to 20 microseconds in 1.5-km clouds, modeled by two scattering components.
Area of Science:
- Atmospheric optics
- Optical remote sensing
- Laser physics
Background:
- Satellite-to-ground communication links are susceptible to atmospheric interference, particularly clouds.
- Understanding laser pulse behavior in clouds is crucial for reliable optical communication systems.
Purpose of the Study:
- To conduct the first measurements of blue-green laser pulse propagation through clouds simulating satellite-to-ground geometry.
- To analyze laser pulse temporal broadening and scattering characteristics as a function of cloud properties and receiver field of view (FOV).
Main Methods:
- Utilized large-diameter (6-km) blue-green laser pulses transmitted through clouds.
- Recorded the time history of transmitted pulses as a function of receiver FOV and cloud optical thickness.
- Modeled the received pulse shape using a combination of two modified gamma functions representing different scattering components.
Main Results:
- Observed maximum pulse stretching of 20 microseconds for nanosecond pulses in 1.5-km thick clouds.
- Demonstrated that pulse shapes can be represented by a sum of a slow (diffusion scattering) and a fast (direct/low-order scattering) decaying term.
- Found that dense clouds primarily exhibited the diffusion-type scattering component.
Conclusions:
- Blue-green laser pulse propagation through clouds is characterized by distinct scattering mechanisms.
- The two-component model effectively describes pulse broadening, differentiating between diffusion and direct/low-order scattering.
- Cloud optical thickness significantly influences the dominance of scattering components, with dense clouds dominated by diffusion.
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