In article ,
Louis Scheffer wrote:
It might be a long way out. The apparent brightness, in photons per
square degree, doesn't change with distance [...] you might
be well out of the solar system before the combined effects make the Sun
eye-safe.

This seems unlikely. Laser beams can be focused to points even smaller
than the sun, and 1 mw lasers are considered almost completely safe...
I don't know the maximum pupil area, but it should be about 1/2 cm^2 at
most, so 20 w/m^2 should be safe...

Depends somewhat on what duration you assume. Winburn's "Practical Laser
Safety" says that for visible light, continuous exposure for 1s, the
threshold of retinal damage seems to be about 10mW/cm^2 = 100W/m^2. But
you want to crank a healthy safety factor into that, not least because
the threshold is rather lower for short-wavelength IR and sunlight has a
fair bit of that.
--
MOST launched 30 June; science observations running | Henry Spencer
since Oct; first surprises seen; papers pending. |