Laser Propulsion
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To understand this technique of propulsion let us first see what are lasers and their properties, which enable them to be used to propel crafts.
Laser is an acronym for light amplification by simulated emission of radiation. It is an intense ray consisting of photons.
Properties of laser


Excitation of an atom
Laser light is monochromatic, directional and coherent
• Monochromatic - means of one wavelength. In contrast, ordinary white light is a combination of different wavelengths.
• Directional- laser light is emitted as a narrow beam and in a specific direction. This property is referred to as directionality.
• Coherent - The light from a laser is said to be coherent. This means that the wavelengths of the laser light are in phase.
Let us see the principle of production of laser light



Working
Principle
The principle of laser propulsion is that it uses mirror to focus the incoming laser beam. This beam strikes the propellant, which is lined at the bottom of the spacecraft. The gases produced propel the spacecraft forward.
The spacecraft consists of 2 components-The light source, which is the high precision laser powered beam and spacecraft designed as a highly polished parabolic mirror capable of receiving light.
Prior to the liftoff, a jet of compressed air is used to spin the spacecraft. This stabilizes the spacecraft. Once the spacecraft is spinning at a constant rate, the laser beam is used which propels the spacecraft into space.