space laser communication

Propagation of EM Waves in Atmosphere - In an Earth environment, electromagnetic waves propagate in ways that depend not only on their own properties but also on those of the environment itself. Since the various methods of propagation depend largely on frequency therefore the complete electromagne..

The smallest lasers used for telephone communication over optical fibres have as their active medium a semiconducting gallium arsenide crystal about the size of a pin-hea..

The development of the laser has opened many avenues of investigation and improved many others. The important characteristics that have contributed to its usefulness in these many areas are tile coherence, monochromaticity and great intensity of its radiation. (i) The smallest lasers..

(in the ruby, at the desired frequency). Such an arrangement is called a Fabry-Perot resonator. Pumping process is carried with the help of flash tube. The spiral flash tube pumps light energy into the ruby in pulses, which are generated by the charge and discharge of a capacito..

How a Laser Works - The below figure shows schematically how a population inversion can be achieved so that laser action-or lasing us it is called can occur. Atoms from the ground state E 1 are "pumped" up to an excited state E 3 , for example by the absorption of light energy f..

Helium - Neon Gas Laser - The figure shows the elements of a type of laser that is often found in student laboratories. The glass discharge tube is filled with a 80%-20% mixture of the inert gases helium and neon. Helium is the "pumping" medium and neon is the "lasing" medium. T..

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Communication Satellites - Communication satellites are normally geostationary satellites. They have devices called transponder which receive signals from an earth station and transmit them in different directions. The signals in the form of electromagnetic radiation are transmi..

Elements of a Communication System..

Space Exploration..