Monday, 30 November 2015

optics - Laser beam sensed by scattering


Can a laser beam, whether it is a IR laser or of the visible to human eye spectrum, be seen/sensed by an electronic eye like a photosensor/photodetector, not human eye, if the beam is just in air? For example if a laser beam is say beamed up in the sky from the ground, can it be detected by an electronic eye like a photosensor/photodetector just because of the scattering from the air?



Answer



In principle, yes, but for clear air the scattering is very very weak, and the scattered light would probably be drowned out by other background sources, especially the blue sky. It would be easier at night.



If the air is not clear, but instead is carrying dust or water droplets or smoke, the beam would be easily visible and recordable, again much more easily at night.


There are plenty of photographs of night-time laser light shows in which the beam is easily visible.


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