Unconventional Laser Guide Stars and Wavefront Correction of Blue Starlight

In this project we established by theory and experiment (1) that a 1/4 Joule, 20 ns, ultraviolet laser pulse could create (near 20 km altitude) a return signal to the transmitting telescope that would appear, for 20 ns, to have a brightness temperature of millions of degrees, and thus serve as a gui...

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Bibliographic Details
Main Author: Hellwarth, Robert W
Format: Report
Language:English
Subjects:
ADAPTIVE OPTICS
Astronomy
CELESTIAL GUIDANCE
CORRECTIONS
GUIDE STARS
LASER APPLICATIONS
LASER GUIDANCE
LASER GUIDE STARS
Lasers and Masers
LIGHT MODULATORS
LIGHT PULSES
MAXWELLS EQUATIONS
Optics
RAMAN SCATTERING
STARLIGHT
ULTRAVIOLET LASERS
WAVEFRONTS
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Summary:In this project we established by theory and experiment (1) that a 1/4 Joule, 20 ns, ultraviolet laser pulse could create (near 20 km altitude) a return signal to the transmitting telescope that would appear, for 20 ns, to have a brightness temperature of millions of degrees, and thus serve as a guide star for high-order corrections of blue starlight, (2) that a much lower energy (approx. one hundred microjoules) femtosecond laser pulse could create an upward-traveling pulse near the tropopause with its wavelength shifted from the driving pulse, (3) that exact, finite-energy, pulse solutions of Maxwell's equations can have an electric (or magnetic) field with zero y-component everywhere in space, (4) that Maxwell's equations place no limit on the smallness of extinction experienced by a focused pulse of finite energy passing through finite crossed polarizers, and (5) that wavefront correctors based on photo-refractive spatial-light-modulators are unlikely to have their speed-of-response improved.