Expose a Hidden Message w/ Polarisation Filters

In summary, the conversation discusses the possibility of using a special type of film to encode hidden messages that can only be revealed when viewed through a polarising filter. The suggested film is PAN F PLUS 35MM, which is a high contrast, sharp and fine-grained black and white film. However, it is mentioned that standard photographic film is not sensitive to polarization and there are other ways to encode hidden messages on it. The conversation also mentions the process of making polarized film, which involves stretching plastic film to create elongated domains that give the film its polarization capability.
  • #1
Phil the tinkerer
3
1
I want to expose a very fine grain film where an image disguises a message but when viewing the through polarising filter allows the message to be revealeded. I envisage exposing the B & W image that is light by light polarised through a positive mask of the message and simultaneously a negative mask light oppositely polarised of the same massage. The idea is the final image will have the property that in natural un polarised light appear to be a simple image but when viewed through a polarising filter the message will be seen. Is what I suggest possible?
 
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  • #2
Ordinary film will not preserve the polarization.
 
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Likes Phil the tinkerer
  • #3
Is there a kind of film which will preserve polarisation? The film I have had suggested is:-

PAN F PLUS 35MM​

35mm, ISO 50, high contrast, super sharp black & white film with very fine grain. Ideal for studio photography and bright, natural light.

  • Slow speed ISO 50
  • Exceptionally fine grain
  • Outstanding resolution & sharpness
 
  • #4
As DrC said, standard photographic film is sensitive to light intensity only, not to polarization. If you want to encode hidden messages, there are other ways to do that on standard photographic film. Have you looked into any of those?
 
  • #5
Thank you for answering. No I haven't where can I learn about those? What search term would you suggest? do you know how polarised film is made? My impression from a long time ago it consists of lines for linear and circles for radial. How close together are the lines? or is this a metaphor for some quantum type effect?
 
  • #6
Phil the tinkerer said:
No I haven't where can I learn about those?
Just try some general Google search terms. Try stuff like Hiding information in images and similar. IIRC one of the techniques is to superpose low-level intensity variations in the image that are not apparent to the naked eye, but carry information (like a low-contrast QR code added to the image that people will not normally notice).

Phil the tinkerer said:
do you know how polarised film is made?
You could search on Poloroid lens or similar to get some good info. IIRC, one way is to heat and stretch the plastic film to make the domains elongated, which gives the film an overall polarization capability in the long direction.
 

FAQ: Expose a Hidden Message w/ Polarisation Filters

What is the basic principle behind using polarization filters to expose a hidden message?

The basic principle involves the manipulation of light waves. Polarization filters can block or allow light waves of certain orientations to pass through. By using a combination of polarized filters, a hidden message can be encoded and later revealed when the correct orientation of filters is applied.

How do you encode a hidden message using polarization filters?

To encode a hidden message, you can use a polarizing filter to write the message on a medium that can alter the polarization of light, such as a transparent sheet. The message is written in such a way that it is only visible when viewed through another polarizing filter oriented at a specific angle.

What materials are needed to perform the hidden message experiment with polarization filters?

You will need at least two polarizing filters, a light source, and a medium to write the message on, such as a transparent sheet or a display screen. Optionally, you may also use a polarizing film to create more complex hidden messages.

Can this technique be used with any type of light source?

While it is most effective with polarized light sources, such as those from LCD screens, it can also work with natural light. However, the contrast and clarity of the hidden message may vary depending on the type of light used.

What are some practical applications of exposing hidden messages with polarization filters?

This technique can be used in various fields, such as security (to create anti-counterfeit measures), art (to create hidden images), education (to teach principles of light and polarization), and in scientific research (to study properties of materials that affect light polarization).

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