Re: Detecting polarization axis

Hi,

to redbelly:
I was also thinking I can use different souces, even in the infrared
range, but what I'm asking is if there are any particular advanteges
using white led instead of infrared diodes or common light bulb. Then,
on the intensity I'll see, why should I still see some light when I
have 2 linear polarized filters (the fixed-one and the testing-one)
rotated 90 degress to each other along my path? If the extinct ratio of
those filters are, say, 10.000:1 I may be able to get that little part,
but it's negligible, so I can consider zero light.

to Salmon Egg:
well, the accuracy I require is to find the angle of the polarization
axis of my tested glass within 0.1 degrees. This is a first prototype.
I'm still googling around with the "half shade prinicple".

Thanks,
Marco



Salmon Egg ha scritto:

On 6/15/06 2:49 PM, in article
1150408183.350963.189630@xxxxxxxxxxxxxxxxxxxxxxxxxxxx, "Marco"
<marco@xxxxxxxxxxx> wrote:

Hi all,

My problem:
I have to find the orientation of the linear polarization axis of some
circular-shape glasses

My solution:
use a white led and a linear polarizer with the investigated glass.
Place all the elements in this order: led -> fixed-polarizer ->
investigated-glass -> light detector. My idea is to make the
investigated glass spin until the detector sees some light from the led
passing through the system, when it sees nothing on its side I know
that the polarization axis of the investigated glass is 90 degrees with
respect to the fixed polarizer and I'm done

Your opinions:
are welcome. I'm looking for comments and suggestions on different
approaches or assembly I can find on the market.

Thanks,
Marco

You don't say if that is a one shot deal or if you have many. You also do
not specify accuracy. If you need high accuracy, look up what is called the
half shade principle.

Bill
-- Ferme le Bush

.

Relevant Pages

  • Detecting polarization axis
    ... I have to find the orientation of the linear polarization axis of some ... use a white led and a linear polarizer with the investigated glass. ... investigated-glass -> light detector. ...
    (sci.optics)
  • Re: Detecting polarization axis
    ... I have to find the orientation of the linear polarization axis of some ... use a white led and a linear polarizer with the investigated glass. ... not specify accuracy. ...
    (sci.optics)
  • Re: Detecting polarization axis
    ... I have to find the orientation of the linear polarization axis of some ... use a white led and a linear polarizer with the investigated glass. ...
    (sci.optics)
  • Re: Detecting polarization axis
    ... I have to find the orientation of the linear polarization axis of some ... use a white led and a linear polarizer with the investigated glass. ...
    (sci.optics)