Andy,
Apparently, the effect is well known. Try a google search using
"photoelasticity with an LCD monitor." You'll get a bunch of hits.
Roger
On 26 Feb 2009, at 2:58 PM, ADavidhazy wrote:
Roger,
Are you sure you looked at the screen with the circular polarizer in
the correct
position? If "backwards" then the 1/4 wave plate "depolarizes" the
beam from
the LCD and not much of an effect will be perceived no matter how
you turn the
filter.
I looked at a 20" Apple LCD monitor and it went pretty black. Must
admit I
used a single, straight, polarizer but a circular one should behave
exactly the
same way if oriented correctly.
my $.01 worth!
andy
Roger Eichhorn wrote:
I just looked at my 15" Powerbook screen and my 20" Apple monitor
through a circularly polarizing filter. The effect is very
slight, ranging from a light tan to a light blue depending on
orientation. However, a roughly square piece of 1/8" thick Lexan,
with two holes drilled in it, when viewed through the filter with
the laptop screen as a light source, shows prominent birefringent
effects. Flexing the Lexan slightly increases the effect as the
stress increases. I'm not familiar enough with the technique to
know whether or not it's suitable for analysis of stress
concentrations.
Roger
On 26 Feb 2009, at 7:44 AM, ADavidhazy wrote:
Herschel,
interesting ... the screens should polarize the same way ... but
you can check this
out by looking at them through a polarizing filter. But I suspect
they all line up
the same way. Hopefully the LCD screens will provide a useful
amount of
illumination for what you are photographing. andy
Herschel wrote:
Thanks Andy. This is really timely good news. No kidding, I was
shooting artwork yesterday afternoon and wishing I had polarized
lighting. I'm gonna take 2 LCD monitors and try it out. I hope
they polarize the same way!
