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.
  • #1
LightningInAJar
213
30
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?
 
Engineering news on Phys.org
  • #2
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".
 
  • Like
Likes hutchphd, LightningInAJar and BillTre
  • #3
I actually have a few small polarized sheets. Not sure if they're the right kind but will see.
 
  • #4
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
 
  • Like
Likes LightningInAJar and BillTre
  • #6
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.
 
  • Informative
  • Like
Likes LightningInAJar, BillTre, berkeman and 1 other person
  • #7
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.
 
  • Like
Likes phinds and BillTre
  • #8
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!
 
  • Haha
  • Like
Likes berkeman and BillTre

Similar threads

Replies
3
Views
1K
  • Quantum Interpretations and Foundations
2
Replies
45
Views
4K
Replies
20
Views
11K
  • Classical Physics
Replies
9
Views
6K
  • Art, Music, History, and Linguistics
Replies
1
Views
1K
  • Special and General Relativity
Replies
13
Views
2K
  • Beyond the Standard Models
Replies
2
Views
2K
  • MATLAB, Maple, Mathematica, LaTeX
Replies
1
Views
2K
  • MATLAB, Maple, Mathematica, LaTeX
Replies
5
Views
3K
Back
Top