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 Post subject: Dr. Hanneman's Tips: 1:Polariscope
PostPosted: Mon Oct 26, 2015 6:53 pm 
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In this section we will explore some of the classic tools developed by Dr. W. William Hanneman as described in his Guide to Affordable Gemology, with some updated observations made by me, Barbra Voltaire. :smt006 , which I think may be helpful to all.

This section is an open, round table discussion. Therefore, anyone wishing to add tips, questions or confusions, is welcome to jump right in to this thread!

I am going to start with the instrument I start every stone identification (except diamonds) using.

The Polariscope.
Definition:
A polariscope uses polarized light for gem identification. It can be easily constructed by attaching 2 properly oriented squares of plastic polarizing material to a support rod. Proper orientation is crossing the filters at right angles so that NO light can penetrate them.
When you look through both filters it will appear dark. This is known as the “crossed position”.
In order to use this for gemological purposes, The crossed polars must be back lit. This can be done with something as simple as placing them on a night light, or setting them in front of a mag light.
Here is the setup used by Dr. Hanneman:
Simply attach the polarized sheets to a support and backlight:
Image
Image

Barbra’s Tip.
Nowadays most all of us carry a cell phone or tablet or have easy access to a laptop.
All these screens are polarized. Therefore, they can act as one of your filters and the light source, in a pinch. Your reaction between the screen and a polarized sheet will be paler than using 2 polarized sheets but it is definitely detectable.
With 2 polarized sheets you can just use the phone or pad as a light source.
Voila! Polariscope in the pocket.
Here is a set-up on my ipad:
Image

Further info:
The Gemology Project on the Polariscope
Gem-A's Video on how to use a polariscope:
https://www.youtube.com/watch?v=4zlIA6SxZNk

Starla Turner's Video on How to Use a Polariscope

Product Source:
Polarized Sheets can be purchased on eBay; I got 10 3x3" for $20.

Plastic and Lucite components: Tap Plastics: http://www.tapplastics.com/

I need some tips on mocking up a coniscope. Anyone?


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 Post subject: Re: Dr. Hanneman's Tips: 1:Polariscope
PostPosted: Mon Oct 26, 2015 8:13 pm 
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My only note would be that many phone screens are circularly polarized now (probably to avoid interacting with plane polarized sunglasses). My current and previous phones both have this "feature."

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 Post subject: Re: Dr. Hanneman's Tips: 1:Polariscope
PostPosted: Mon Oct 26, 2015 8:19 pm 
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Thanks Stephen. Good point.
Therefore, they can only be used as handy backlights.


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 Post subject: Re: Dr. Hanneman's Tips: 1:Polariscope
PostPosted: Mon Oct 26, 2015 9:37 pm 
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Bought 2 - 49mm Polarizing Linear PL Lens Filter - for $7.98 total on ebay. 2 inch PVC pipe and a nightlight plus some cutting of the pipe makes a desk polariscope.

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 Post subject: Re: Dr. Hanneman's Tips: 1:Polariscope
PostPosted: Mon Oct 26, 2015 10:20 pm 
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Pictures, Bob?
Sounds like a winner.
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FYI 49mm= approx 2"
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I was thinking since I have 3" square polarized sheets, I could cut them down slightly to 2" and use the leftover for a Hanneman dichroscope!
I'll follow up with 2: Dichroscope. :D

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FYI2: One polarizing filter makes the screen on my MacBook Pro go totally black. :D
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 Post subject: Re: Dr. Hanneman's Tips: 1:Polariscope
PostPosted: Tue Oct 27, 2015 2:00 am 
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Barbra Voltaire wrote:
I need some tips on mocking up a coniscope. Anyone?
A 10x loupe inserted between the stone and the upper polarizer produces conoscopic images of the interference figure. The photograph shows a more elaborate set-up, but the principle is illustrated.


Attachments:
Polariscope.jpg
Polariscope.jpg [ 148.17 KiB | Viewed 2485 times ]


Last edited by Duncan Miller on Sat Oct 31, 2015 2:04 am, edited 1 time in total.
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 Post subject: Re: Dr. Hanneman's Tips: 1:Polariscope
PostPosted: Tue Oct 27, 2015 11:52 am 
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I've heard one can use a loupe as a coniscope from Tim Spauwen years ago. I guess it's about time I tried it. :oops:


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 Post subject: Re: Dr. Hanneman's Tips: 1:Polariscope
PostPosted: Sat Dec 05, 2015 11:53 pm 
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Hi - I just made a polariscope from a piece of PVC pipe, a bit of plexiglass two polarized filters a couple rounds of wood, and a dollar store light.
Cut PVC into three sections. cut wood rounds to fit on top of them.
Drill holes in wood rounds.
Glue wood rounds on top of two pieces of PVC pipe.
Glue polaroid filter over holes.
Glue one round piece of plexiglass that fits inside the pipe on top of one polaroid filter.
Glue one round piece of pexiglass on top of the third piece of pvc.

Glue two of the PVC pieces together. One that has the glass on top, on top of the one that has the filter NOT covered with glass.

Glass
glue
PVC
glue filter
wood
glue
PVC

glass
glue filter
PVC


Light is turned on and the thing assembled.
Rotate the top piece until the polarizers are crossed.




Image
Image
Image


It was certainly cheap.


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 Post subject: Re: Dr. Hanneman's Tips: 1:Polariscope
PostPosted: Sun Jan 28, 2018 12:16 am 
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Barbara, I know that you are crazy busy.......

Any other updates coming?

I seem to remember a thread that was waiting for an update from Dr Hanneman on something, but I lost track of it.

Thanks for all you have done for this forum.......


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