Benm
0
- Joined
- Aug 16, 2007
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- 7,896
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Oh well, 'it can been seen from outer space'. I suppose that in itself isnt false, but it would mean this is not the only laser that can be seen from outer space either.
I think it would not require much to make this claim, only the correct circumstances that provide the contrast. If you stand in the middle of a desert at night, and the ISS flies overhead, pointing at it would probably make you visible with a minumum amount of power.
Considering 1 mrad divergence, the dot would be 350 meters radius at the iss altitude, or almost 400.000 square meters. With 100 mW output power, this would mean something in the order of 0.25 uW/m2. Going into an eye you get another 10^7 or so reduction, to 0.025 pW.
But there is the catch: We have 2.5 E-14 watts entering the eye. This equates to about 67000 532nm photons per second. As it has been demonstrated that the eye can see a single photon, i'd say its very feasible that this laser would be visible by dark adapted eyes. Then again, this also goes for a 1 mW cat toy
I think it would not require much to make this claim, only the correct circumstances that provide the contrast. If you stand in the middle of a desert at night, and the ISS flies overhead, pointing at it would probably make you visible with a minumum amount of power.
Considering 1 mrad divergence, the dot would be 350 meters radius at the iss altitude, or almost 400.000 square meters. With 100 mW output power, this would mean something in the order of 0.25 uW/m2. Going into an eye you get another 10^7 or so reduction, to 0.025 pW.
But there is the catch: We have 2.5 E-14 watts entering the eye. This equates to about 67000 532nm photons per second. As it has been demonstrated that the eye can see a single photon, i'd say its very feasible that this laser would be visible by dark adapted eyes. Then again, this also goes for a 1 mW cat toy
