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Atmospheric and fog attenuation, which are exponential in nature, limit practical range of FSO devices to several kilometers. However, free-space optics based on 1550 nm wavelength, have considerably lower optical loss than free-space optics using 830 nm wavelength, in dense fog conditions.
The reciprocal of the Greenwood frequency is sometimes known as the Greenwood or atmospheric time constant (τ 0). Since the distortions are approximately constant over a period less than this time constant, adapting the optical system at a faster rate yields negligible benefits; conversely, adaptive system performance degrades significantly as ...
Meteorological optics is "that part of atmospheric optics concerned with the study of patterns observable with the naked eye". [2] Nevertheless, the two terms are sometimes used interchangeably. Meteorological optical phenomena, as described in this article, are concerned with how the optical properties of Earth's atmosphere cause a wide range ...
In 1981, Fried carried out the first analysis evaluating and establishing the feasibility of the use of atmospheric laser back scatter to control adaptive optics—a concept which now goes by the name of laser guide-star. He then designed, managed the development of the hardware for, and supervised an experiment that successfully demonstrated ...
The optical atmospheric window is the optical portion of the electromagnetic spectrum that passes through the Earth's atmosphere, excluding its infrared part; [10] although, as mentioned before, the optical spectrum also includes the IR spectrum and thus the optical window could include the infrared window (8 – 14 μm), the latter is ...
Powerful laser guide star system at the Paranal Observatory. The actual laser guide star is the small spot above the apparent end of the laser beam. A laser guide star is an artificial star image created for use in astronomical adaptive optics systems, which are employed in large telescopes in order to correct atmospheric distortion of light (called astronomical seeing).
Atmospheric optical phenomena include: Afterglow; Airglow; Alexander's band, the dark region between the two bows of a double rainbow. Alpenglow; Anthelion; Anticrepuscular rays; Aurora (northern and southern lights, aurora borealis and aurora australis) Belt of Venus; Brocken Spectre; Circumhorizontal arc; Circumzenithal arc; Cloud iridescence ...
Atmospheric Optics site graphical user interface. It creates simulations by accurately tracing up to several million light rays through mathematical models of ice crystals. 2010 Halopoint2 Jukka Ruoskanen webpage graphical user interface. Ray-tracing code for various ice crystals with graphical user interface 2008 HALOSKY [5] Stanley David ...