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spot the error III
https://www.gemologyonline.com/Forum/phpBB2/viewtopic.php?f=19&t=4332
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Author:  Doos [ Fri Nov 30, 2007 10:58 am ]
Post subject:  spot the error III

Hi,

When polarization is explained on the level of gemmology students, we usually illustrate it with what is named a "wire-grid polarizer".
In the image the wires in the polarizer are orientated vertically and the polarized wave vibrates in the north-south direction.

Image

Question: Is there anything wrong with this picture and if so, what?

Author:  JB [ Fri Nov 30, 2007 11:44 am ]
Post subject: 

Are we to assume the light wave passing through the grid has already been linearly polarized?

Author:  Doos [ Fri Nov 30, 2007 11:45 am ]
Post subject: 

Yes.

Author:  JB [ Fri Nov 30, 2007 11:57 am ]
Post subject: 

Can we assume there is another unseen polarizing grid orientated 90deg. to the wire grid shown in the picture?

Author:  Alberto [ Fri Nov 30, 2007 12:05 pm ]
Post subject: 

maybe there's another unseen polarized grid oriented LIKE the one is visible in the scheme...

Author:  Doos [ Fri Nov 30, 2007 12:05 pm ]
Post subject: 

I'm not the one who dictates what you may or may not assume. Only you can, but the image itself should be more than plenty.
One filter, one wave.

Author:  Alberto [ Fri Nov 30, 2007 12:15 pm ]
Post subject: 

what i see in this image is: a wave vibrating only on a plane so it has been filtered by a vertical grid (like the one in the picture) before entering in the image, then the wave passes through the grid.

Author:  JB [ Fri Nov 30, 2007 12:17 pm ]
Post subject: 

I don't see a problem with the picture then. Wire grid, picket fence and a linearly polarized light wave vibrating in a direction parallel to the grid orientation.

Looks right to me.

Author:  Alberto [ Fri Nov 30, 2007 12:18 pm ]
Post subject: 

and to me too...

Author:  Doos [ Fri Nov 30, 2007 12:18 pm ]
Post subject: 

Hi,

Yes that is what the image is showing.
The question is: is the propagation of the wave in this image correct or not?

Could be correct, could also not be correct.

Quote:

Yes that is what the image is showing.
The question is: is the propagation of the wave in this image correct or not?

Could be correct, could also not be correct.

Author:  Doos [ Fri Nov 30, 2007 12:22 pm ]
Post subject: 

Ok, JB and Ravirus have come to an agreement.
Anymore takers?

Remember, could be correct or wrong.

Author:  squeaky [ Fri Nov 30, 2007 1:29 pm ]
Post subject:  I'm studying....but don't wait on me...

Doos,
I'm carefully studying this but have no answer so don't wait on me to post the answer. This is something I'm still having a little trouble grasping. I'm looking forward to more information from you....

THANKS FOR DOING THIS!!!!
Lyresa

Author:  squeaky [ Fri Nov 30, 2007 1:40 pm ]
Post subject:  Confusion about this...

Here's one thing that confuses me about this whole concept. In the Gemology Project info on polarizing filter, it states the following:

"When you place a polarization filter in North-South (N-S) position, only waves vibrating in the E-W direction (or plane) are able to pass through the filter. As you rotate the filter to other positions, other orientations will pass through. This is what we call "plane polarized light", it only vibrates in one plane...."

Doos, I read in your post that you indicate the light is vibrating N/S but here it states that wouldn't go through. AM I CONFUSING 2 THINGS HERE?

Until now, light waves and their actions are something I've never had an opportunity to learn so am having to beat this into my old brain...

THANKS!
Lyresa

Author:  Doos [ Fri Nov 30, 2007 2:00 pm ]
Post subject: 

Hi,

That statement on the project needs to be rewritten to include the orientation of the wires in the wire-grid. See the discussion page of that page.

Author:  squeaky [ Fri Nov 30, 2007 2:22 pm ]
Post subject:  Error then?

Doos - THANKS!

Then, if I'm reading and UNDERSTANDING this right, the beam will not pass thru the grid. Instead, due to the orientation of the wires and the beam going the same direction, the energy of the wave will cause the electrons in the wire to begin vibrating and therefore absorbing the energy. This basically destroys the wave. If the beam were traveling E/W, it WOULD continue as shown.

Thus my answer is ERROR as the beam should NOT continue THRU the grid.

Lyresa

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