Polarized imaging with a stereo?

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Gasman
Posts: 153
Joined: Sat Jan 09, 2016 1:36 pm
Location: North East UK

Polarized imaging with a stereo?

#1 Post by Gasman » Tue Dec 07, 2021 9:23 pm

Hi guys
Been enjoying doing some polarised imaging with my Leitz compound scope. I recently bought a new stereo scope with both incident and transmitted led light and wondered if there is anything to be gained with trying polar imaging with my a stereo scope?. I 3d printed a few bits for my scope to try it on some Magnesium Chloride crystals which came out not bad but room for improvement but would be interested if anyone else has tried it.
Thanks
Steve
polarsetup2.jpg.ed71bcfbe7cb4e18b3caf2d07b58b451.jpg
polarsetup2.jpg.ed71bcfbe7cb4e18b3caf2d07b58b451.jpg (102.81 KiB) Viewed 2567 times
Magnesium chloride melted over t-lite
Magchloride.thumb.jpg.88ccd3ebbb522113adcbb13fb8774256-min.jpg
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MichaelG.
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Location: North Wales

Re: Polarized imaging with a stereo?

#2 Post by MichaelG. » Tue Dec 07, 2021 11:08 pm

Looks promising … definitely worthy of further experimentation

I can’t be sure, but I think you might do better with a linear pol instead of circular.

MichaelG.
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Edit: __ Just remembered [and located!] this previous discussion :
viewtopic.php?t=7196
Last edited by MichaelG. on Tue Dec 07, 2021 11:33 pm, edited 1 time in total.
Too many 'projects'

crb5
Posts: 101
Joined: Sat Sep 12, 2020 11:55 pm

Re: Polarized imaging with a stereo?

#3 Post by crb5 » Tue Dec 07, 2021 11:33 pm

Circular polarizers work fine as long as you have the quarter-wave plate side pointing away from the sample for both top and bottom polarizers https://youtu.be/iNNkdHyvhbs

Scarodactyl
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Joined: Sat Mar 03, 2018 9:09 pm

Re: Polarized imaging with a stereo?

#4 Post by Scarodactyl » Wed Dec 08, 2021 12:09 am

For some precise measurements the stereo light paths being off axis can affect readings, but otherwise it is a fairly popular add-on available for most any stereo. Aso nice in combination with a polarized ring light so you can fine tune reflections.

Gasman
Posts: 153
Joined: Sat Jan 09, 2016 1:36 pm
Location: North East UK

Re: Polarized imaging with a stereo?

#5 Post by Gasman » Wed Dec 08, 2021 7:43 am

Hi guys
Like Michael suggested and also suggested by a friend that you can't really get true optical extinction with a circular pol filter and a linear one but two linears are needed, just waiting for one !
Steve

Greg Howald
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Joined: Tue Oct 20, 2020 6:44 am

Re: Polarized imaging with a stereo?

#6 Post by Greg Howald » Wed Dec 08, 2021 1:39 pm

It has been pot luck for me. I have purchased polarizing lenses and sheets from Amazon which is really easy to do. Unfortunately with Amazon I haven't found any description in the advertisement of the products to tell what type of polarization is being purchased.
Greg

crb5
Posts: 101
Joined: Sat Sep 12, 2020 11:55 pm

Re: Polarized imaging with a stereo?

#7 Post by crb5 » Wed Dec 08, 2021 9:21 pm

Like Michael suggested and also suggested by a friend that you can't really get true optical extinction with a circular pol filter
Can anyone explain this? A circular polarizer is a linear polarizer in combination with a quarter-wave plate. As long as the linear polarizer sides are are facing each other and are crossed at 90 degrees they should produce extinction. I use two circular polarizers on my microscopes and get satisfactory extinction.

Scarodactyl
Posts: 2775
Joined: Sat Mar 03, 2018 9:09 pm

Re: Polarized imaging with a stereo?

#8 Post by Scarodactyl » Thu Dec 09, 2021 4:34 am

I don't think there's any reason it shouldn't work in theory. In practice the common camera ones tend to not quite give full extinction, though for most usage that shouldn't be an issue.

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