How are polarization test cards created for proving polarized glasses?

In summary, polarization test cards are made using a thin polarized film, typically polyvinyl alcohol (PVA) plastic with iodine doping, which is laminated onto the card. The film is stretched during manufacture to align the PVA chains in one direction. This process is also used to make polarized sunglasses. The test cards can be tested by looking at a screen at different angles, and can be made with both linear and circular polarization. The film also has a multi-layer coating to reduce direct reflection from the front surface. There are many resources available online for more information on how polarized cards are made.
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LightningInAJar
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I could swear I saw this topic in the forum in the past but haven't found it today. I was curious how polarization test cards are made to prove that a pair of glasses are polarized. Special ink or paint? What is that type of substance called or commonly used for? I'd love to use it for art. Does it require special paper medium? Anyone ever make printer ink cartridges with an ink invisible only without polarized glasses?
 
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LightningInAJar said:
I was curious how polarization test cards are made to prove that a pair of glasses are polarized. Special ink or paint?
Chemistry could print a circular molecular polarizer, but how might you align a linearly polarized ink?

My guess is that a thin polarized film is laminated onto the test card, the same film as used to make polarized sunglasses.
https://en.wikipedia.org/wiki/Polarizer#Absorptive_polarizers
"Its current H-sheet form is made from polyvinyl alcohol (PVA) plastic with an iodine doping. Stretching of the sheet during manufacture causes the PVA chains to align in one particular direction".
 
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  • #3
I actually have a few small polarized sheets. Not sure if they're the right kind but will see.
 
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LightningInAJar said:
I actually have a few small polarized sheets. Not sure if they're the right kind but will see.
The "right kind" to do what?
 
  • #5
LightningInAJar said:
I was curious how polarization test cards are made to prove that a pair of glasses are polarized.
I have no answer to your particular question, but in case you weren't aware of it, I just wanted to say that glasses can often be tested for polarization by looking with them at a screen (tv, computer etc) at different angles. I've noticed this since I often wear sunglasses :smile:.

Regarding linear and circular polarization I just fetched two of of my polarizing filters (one linear, one circular) for camera lenses and tested them on my screen, and they both worked:

1. Linear polarizing filter (at different angles):

1a.jpg


1b.jpg


1c.jpg


2. Circular polarizing filter (at different angles):

2a.jpg


2b.jpg


2c.jpg
 
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Screens are now often clad in a circularly polarized film. Incident light, say LHP entering, is absorbed on the first pass, so only RHP survives to be reflected. But the reflection reverses the CP hand, to make the RHP reflect as LHP, which is absorbed on the second pass through the filter. That process of reversal, also operates on multiple internal reflections, which is why you no longer see your reflection in your computer monitor.

Direct reflection from the front surface of the CP film is also reduced by a multi-layer coating of that surface, with quarter-wave thicknesses of impedance matching materials.
 
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It's done with polarizing film. How do I know? I asked Google. "how are polarized cards made" Zillions of hits,

You really should try Google sometime.
 
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Vanadium 50 said:
It's done with polarizing film. How do I know? I asked Google. "how are polarized cards made" Zillions of hits,

You really should try Google sometime.
I did. I even asked a company that sells them. The sales guy had no idea.
 
  • #9
I guess Google just deliberately refused to give you the answer. Bad Google! Bad, naughty Google!
 
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FAQ: How are polarization test cards created for proving polarized glasses?

1. What materials are used to create polarization test cards?

Polarization test cards are typically made from a combination of polarizing film and a substrate material such as plastic or cardboard. The polarizing film is crucial as it filters light waves to demonstrate the polarization effect.

2. How does the polarizing film work in these test cards?

The polarizing film in the test card works by allowing only light waves of a specific orientation to pass through. When polarized glasses are used to view the test card, the alignment of the lenses with the film will either block or allow light, creating a visible pattern that proves the glasses are polarized.

3. What patterns or images are typically printed on polarization test cards?

Polarization test cards often feature patterns such as grids, stripes, or specific images that change appearance when viewed through polarized lenses. These patterns are designed to clearly demonstrate the polarization effect by showing contrast or color changes.

4. How are the polarization test cards tested for accuracy?

To ensure accuracy, polarization test cards are tested by viewing them through a known polarized lens. The test card is rotated, and the change in visibility of the pattern is observed. If the pattern changes as expected, the card is deemed accurate.

5. Can polarization test cards be reused multiple times?

Yes, polarization test cards can be reused multiple times as long as they are not damaged. The polarizing film and printed patterns are designed to withstand repeated use, making them durable for multiple tests.

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