What are the uses of 530nm and 147.3nm wave plates

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Guercini
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What are the uses of 530nm and 147.3nm wave plates

#1 Post by Guercini » Sat Oct 31, 2020 5:14 pm

All I know is that 530nm is "Full-Wavelength Retardation" plate and 147.3nm is "Quarter-Wavelength". I would like to know the different applications for each. If I can have only one of these which one would be "better" to own? Thanks in advance for guidance and info on these plates.

PeteM
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Re: What are the uses of 530nm and 147.3nm wave plates

#2 Post by PeteM » Sat Oct 31, 2020 7:07 pm

This might get you started. The wave plates are typically used in association with a polarizer and an analyzer - between crossed polarizers. So first you want (and probably already have) a decent polarizer and analyzer (with good extinction and no apparent optical defects).

The designations of the plates refer to how much of a wavelength of green light the plate can retard in one of those polarized directions. One full wavelength (near that 530nm depending on maker) or one quarter wavelength. There's a notable color shift, dependent upon polarized light path length through the specimen.

The uses might be divided into to two parts - quantitative applications (measuring retardation and phase differences in a specimen) and visual (enhancing contrast and colors). For example, identification of crystal and mineral composition is a quantitative application. Seeing and identifying gout crystals is a specific medical example. If one polarizer is just above the field lens (base of the scope), the wave plate can rest on top or be put in a filter tray below the condenser. It can also fit in a slot often provided above the objectives and below the upper polarizer/analyzer.

I'd assume you're interested in visual differences -- and suggest you acquire cheap versions or make your own. Between rotating one polarizer and/or the wave plate you can get a wide variety of visual effects.

A wave plate is also often a component of DIC systems.

Forum member Stitchy Mitch was doing a tutorial on polarized light, maybe he and others will have more to add.

This article shows some comparisons for one crystal sample. Just crossed polars are pretty interesting.

http://www.microscopy-uk.org.uk/mag/ind ... jcomp.html

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mrsonchus
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Re: What are the uses of 530nm and 147.3nm wave plates

#3 Post by mrsonchus » Sat Oct 31, 2020 7:49 pm

Hi, I often use polariser and full-lambda plate when examining xylem elements of plant tissues. Transvers and longitudinal orientations of fibers will show different (opposite) colours when crossing the retardation at an angle - giving indication as either yellow or blue as the xylem elements are rotated. This works very well also I find for cell-wall fibers and pits.
Here's a great article and downloadable PDF re this - see this link...

Here's an example of xylem vessels with full-lambda retardation of crossed-polarisers,

Xylem vessels spirals using 'Only' crossed-polarisers - everything birefringent shines without directional differentiation,
Image

As seen with the full-lambda plate,
Image

Here I use this for picking out some very fine detail of 'cross-members' between the spriral-bars, rather than attention to direction in particular,
Image

As seen with full-lambda plate added,
Image

alternative orientation,
Image

Finally of course the plate may be used just to make a beautiful image, as what appear to be sclerids or maybe broken xylem spiral are seen in this hand-section of untreated plant stem,
Image

There are many uses beyond my simple excursions though, see the linked-to article above etc...
John B

PeteM
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Re: What are the uses of 530nm and 147.3nm wave plates

#4 Post by PeteM » Sat Oct 31, 2020 8:17 pm

Great examples and beautiful images, John.

Guercini
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Re: What are the uses of 530nm and 147.3nm wave plates

#5 Post by Guercini » Sun Nov 01, 2020 2:11 am

Thank you very much Pete and John! Great information.

microb
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Re: What are the uses of 530nm and 147.3nm wave plates

#6 Post by microb » Sun Nov 01, 2020 5:53 am

Would be curious about the properties of a 1/4 wave retarder using a film such as this:

https://www.edmundoptics.com/f/polymer- ... ilm/14827/
Last edited by microb on Mon Nov 02, 2020 11:04 am, edited 1 time in total.

Greg Howald
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Re: What are the uses of 530nm and 147.3nm wave plates

#7 Post by Greg Howald » Sun Nov 01, 2020 2:20 pm

I appreciate this post and it's responses. I'm comfortable with my compound scope, but I've only had the petrographic scope for a couple of months. Very new to it. This post has taught me some things and I downloaded the info you folks made available and have shared the men with my brother.
Thanks, Greg

Plasmid
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Re: What are the uses of 530nm and 147.3nm wave plates

#8 Post by Plasmid » Sat Feb 13, 2021 12:06 am

Greg Howald wrote:
Sun Nov 01, 2020 2:20 pm
I appreciate this post and it's responses. I'm comfortable with my compound scope, but I've only had the petrographic scope for a couple of months. Very new to it. This post has taught me some things and I downloaded the info you folks made available and have shared the men with my brother.
Thanks, Greg
Greg, I was wondering if you had any luck with the plates? Im considering purchasing one or more for my set up and had a couple of questions for you or anyone on this forum on regards to the plates.

1.Is there any variation of differences in plates like the ones in the picture below, the seller doesn't specify if different effects can be attributed to each plate ( base on color) or are all retarder plates the same?
2. On regards to the placement of the plate, are they solely used in between the polarizer and analyzer?
3 . Can more than one plate be used at the same time?
Thank you in advance.
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Greg Howald
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Re: What are the uses of 530nm and 147.3nm wave plates

#9 Post by Greg Howald » Tue Feb 23, 2021 2:19 am

I think ( not really sure) the wave plates will filter out color in particular ranges of the wavelength of color. Red has a range. Blue has a range. I doubt if you could use more than one plate per slot. In my metallurgical scope of I place a red filter in the top light and a blue filter in illuminator I can get purple. Pretty but without a spectroscope I could never guess the true wavelength.
Greg

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