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PostPosted: Sun Jul 14, 2019 11:42 am 
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Hello everyone

Does anyone have experience with making DIY wave retarder plates for polarized light studies? I tried making one out of cellophane but it was not optically clear and deteriorates the image quality when placed between the specimen and analyzer; when placed between the polarizer and specimen it produces interesting interference effects but I don't think thats technically the same thing (effects of this device together with polarizer rotation attached below). Perhaps someone knows of a cheap and optically clear material that I can use (the cellophane I used was the kind that comes with microscopes slides).

Thanks
Wes


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PostPosted: Sun Jul 14, 2019 2:36 pm 
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Wes,

I don't think optically clear "lamda plate" material that you can place above obejctives can be found cheaply. Unless you found a surplus eBay seller who knows nothing about his stuffs. I would jump on it before you, if there is one :twisted:

I used cheap cellophane "lamda plate" the cheap way, below sample and above polarizer, and like the esthetics. But that is only good for hobby use.


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PostPosted: Sun Jul 14, 2019 3:13 pm 
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Yes I missed a new full lambda plate from Zeiss for $85.00, it was mislabeled in terms of its manufacturer (probably explaining the nice price) but I forgot the bidding deadline and I really regret it.


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PostPosted: Mon Jul 15, 2019 2:23 am 
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Try mica. It used to be the material of choice :-)

Cheers,
John


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PostPosted: Mon Jul 15, 2019 4:58 am 
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Edmund optical has lambda plate plastic sheet available for about 15 bucks for a 2 inch square.


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PostPosted: Mon Jul 15, 2019 6:59 am 
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abednego1995 wrote:
Try mica. It used to be the material of choice :-)

Cheers,
John

Microworldofgems wrote:
Edmund optical has lambda plate plastic sheet available for about 15 bucks for a 2 inch square.

Thank you John and Microworldofgems. These are great ideas!


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PostPosted: Mon Jul 15, 2019 2:50 pm 
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Hi Wes,
not tried for microscopy, but might be an idea: The plastic foil to wrap flowers in is optically very nice.
Another source may be screen protectors for cameras and smart phones and display windows of cameras and objective covers of smartphones.

It also is a big question whether you want a retarder of unspecified properties or something precise to use on a polarizing microscope = measuring device with added image option.
I'm sure that the original lambda plates have the right amount of retardation but I wouldn't bet on them supporting perfect image quality as this is not necessary for pol work.

Bob


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PostPosted: Mon Jul 15, 2019 8:18 pm 
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MicroBob wrote:
...not tried for microscopy, but might be an idea: The plastic foil to wrap flowers in is optically very nice.
Hi Bob, actually, the popular transparent foil for flower wraps is cellophane.

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PostPosted: Tue Jul 16, 2019 11:28 am 
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If its really clear the flower shop cellophane might be just what I need. Neat suggestion!


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PostPosted: Tue Jul 16, 2019 11:47 am 
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Our house is very old, built began in the last months of WW2. When we bought it in 2000 there were still some single pane windows and we used this flower foil to get a bit better isolation without much effort. So I have looked a lot through this material! :lol:

Bob


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PostPosted: Tue Jul 16, 2019 1:23 pm 
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Microworldofgems wrote:
Edmund optical has lambda plate plastic sheet available for about 15 bucks for a 2 inch square.
What I found ◊Ěn their site at these prices are pieces of flexible modified polycarbonate film. Thickness is not specified. They also sell "polymer" retarders, which are sandwitched film between two glass plates. But for 10X the price.
In fact, flat hard transparent CD/DVD plastic packages are made of polycarbonate (guess); I wonder if they can serve as retarders (what with the tiny scratches...).

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PostPosted: Tue Jul 16, 2019 2:51 pm 
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Look at the 50mm x x50mm. Full, 1/2 and 1/4 wave. $18 each for the full wave, $12 each for the 1/2 and 1/4. Click on "Specifications and Documents" below each description to get the full data, including thickness. Put them below the condenser as they are not optically clear enough to go between the specimen and the eyepiece.

https://www.edmundoptics.com/search/?cr ... 3AMTQ4Mjc1


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PostPosted: Tue Jul 16, 2019 4:00 pm 
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Hobbyst46 wrote:
In fact, flat hard transparent CD/DVD plastic packages are made of polycarbonate (guess);


Hi Doron, I think they are Polystyrene, cheap and transparent.

Bob


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PostPosted: Tue Jul 16, 2019 6:05 pm 
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Check out this post.
http://www.microbehunter.com/forum/photographs-and-videos/pediastrum/

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PostPosted: Wed Jul 17, 2019 8:53 pm 
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MicroBob wrote:
Hobbyst46 wrote:
In fact, flat hard transparent CD/DVD plastic packages are made of polycarbonate (guess);


Hi Doron, I think they are Polystyrene, cheap and transparent.

Bob
Bob, thanks for the correction; yes it is polystyrene.

Just for fun, I performed a small experiment with cellophane and a CD package plate. Such experiments have been done and posted by other folks in the past.

1) Sandwiched A 2cm x 2cm piece of thin flower-wrap cellophane between twp slides, placed the sandwich-slide on top of the polarizer (which in turn is laid on the field aperture). The other polarizer in inside the head, above the objectives. Rotation of the sandwich-slide creates a partial spectrum of background colors. Adding a second layer of cellophane creates a full spectrum and fairly strong coloration.

2) Cut a 2cm X 2cm piece of solid transparent polystyrene from the front plate of a DVD package. Placed the piece on the polarizer on top of the field aperture, and repeated the experiment. The same rainbow effect was obtained. I was not sure about the birefringence of PS, but there it is and it works.

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PostPosted: Thu Jul 18, 2019 2:58 pm 
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MICA is one of the materials for making retarders. I just noticed that small MICA plates are being sold, very cheaply (a few $$ apiece) as replacement parts for microwave ovens. Various dimensions. No idea about their optical properties - transparency, etc - maybe someone will try those.

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PostPosted: Fri Jul 19, 2019 7:16 pm 
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Seb28 wrote:
Tom Jones wrote:
Look at the 50mm x x50mm. Full, 1/2 and 1/4 wave. $18 each for the full wave, $12 each for the 1/2 and 1/4. Click on "Specifications and Documents" below each description to get the full data, including thickness. Put them below the condenser as they are not optically clear enough to go between the specimen and the eyepiece.

https://www.edmundoptics.com/search/?cr ... 3AMTQ4Mjc1

Thats kind of what I'm doing now. A piece of polystyrene or cellophane goes above the polarizer but below the condenser (thats how I get the images in the OP). But technically speaking that's not the same as a dedicated phase plate that's going above the specimen, is it?


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