Stargazer arrested for using green laser

Oh, I didn't mean looking into the beam. Someone added that
annotation. I meant looking the reflection of the laser off the wall.

I might give it a try tonight, will let you know.

Mark


canopus56 wrote:
Mark wrote:
Stand 6 feet away (just to the side of the beam) and take a
flash photograph [looking into the beam]. It seems to me
that if laser is brighter than the flash, the spot will
still be visible in the picture. Any thoughts? Is this a
valid experiment?

I don't know. On first impression, the laser pointer's coherent beam
is
less than the diameter of the human eye pupil and the camera iris.
The
flash bulb's light is dispersed across a wide-area larger than the
human eye pupil and the camera iris. Therefore, the general public
might disregard any analogy between the two light sources.

But your idea sounds like it's worth a digital camera click and
flash.
(On second thought, I'd do that test with film and not risk damage to
a
digital camera chip.) Because the laser beam is only 1-2mm in
diameter
at 2 meters and the beam is similar in brightness to the -26 mag
Sun's
disk, I would expect the beam to still be visible in the flash. Let
the
group know what you find. - Canopus56

n what the beam does at
distances greater than 300ft (e.g. stepping in and out of the beam at a
large distance with a brief, glancing eye exposure) - just so I'll have

Your exposing your eyesight to a hazard that might not be reversable. Why not
use a photographic light meter and then plot Lumens agaist distance from
center. This would be a lot more quantitative and subject to analysis.

Too late - empirical evidence suggests very that brief exposure from a
distance of approximately 18 inches results in no lasting damage, and
nothing detectable beyond 5 minutes or so. :-)


HAVRILIAK wrote:
n what the beam does at
distances greater than 300ft (e.g. stepping in and out of the beam
at a
large distance with a brief, glancing eye exposure) - just so I'll
have

Your exposing your eyesight to a hazard that might not be reversable.
Why not
use a photographic light meter and then plot Lumens agaist distance
from
center. This would be a lot more quantitative and subject to
analysis.

Too late - empirical evidence suggests very that brief exposure from a
distance of approximately 18 inches results in no lasting damage, and
nothing detectable beyond 5 minutes or so. :-) BRBR


The most important question in such a LASER test is did you have your eyes
focused at infinity? If you were focused at the head 18 inches away, you will
get a fairly large blur circle on the retina. If focused at infinity (LASER is
the same as the object distance being infinite -- parellel rays) you can get
all the power in a very small dot on the retina. It is an old lab trick to keep
your eyes focused on nearby objects when working with LASERs.

-- Charlie Springer