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!
