Expose a Hidden Message w/ Polarisation Filters

[Phil the tinkerer]

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?

 

[DrClaude]

Ordinary film will not preserve the polarization.

 

[Phil the tinkerer]

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

 

[berkeman]

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?

 

[Phil the tinkerer]

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?

 

[berkeman]

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).

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.