Re: Projection lamps

[P3D Gabriel Jacob <jacob@xxxxxxxxxxxxxx>]

Larry Berlin writes

>I know that the *experts* claim that we aren't really aware of light level
>changes that are very rapid, but I certainly am aware of 60 Hz fluctuations
>and I suspect the nervous system responds to high speed fluctuations even if
>it's at a very subtle level. Battery operated viewers are flicker free
>unless they have a bad connection in the switch.

Well Larry, their is another bunch of experts that back up your claim.
Not exactly in regards to light fluctuations but with something more
subtle. I remember reading (but don't remember where) that even the
scan lines on a tv can be sensed. Normally the scan lines go from top
to bottom, but in a study, they made the scan lines go from the bottom
up. The test subjects felt uncomfortable with this setup. I don't know
how they tested for this thou.
There is a simple test you can do to test for the fluctuations on a 
monitor. This is basically like a strobe light. Just wave your finger
and you'll notice you can see several individual fingers. If the monitor
or tv had a frame rate of 0 you would not be able to see your finger but
would see a blur. On a incandescent or flourescent lamp you can't readily
see your finger but the fluctuations are there. (There are other examples
that can be tried such as moving LED display calculators up and down very
quicly and others.) This can be verified with a silicon sensor and scope.
Flashing light and fluctuations also have been documented to effect 
brain waves and thus state of mind, at much lower frequencies and used to
that advantage with light goggles. So I don't see why higher frequencies
wouldn't have an effect on the mind imperceptibly.

P.S. Another way to see the scan lines on your monitor is to hum a few
bars! No I am not kidding. Just hum with a very low and deep voice
(any song will do) and you will see black wavy lines on your monitor.
I can't hum well enough to see anything on a flourescent lamp thou. ;-)

Gabriel


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