How to create diffraction gratings from negative film

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SUMMARY

This discussion focuses on the challenges of creating diffraction gratings using negative film from disposable cameras. The primary issue highlighted is the film's resolution limitations, with Kodak Color films achieving only 20 to 30 lines per mm, while optical gratings require at least 300 L/mm for effective results. Participants suggest avoiding flash photography to reduce glare and recommend using alternative materials like CD or DVD surfaces for better grating quality. The importance of proper focusing and setup is emphasized for achieving clear diffraction patterns.

PREREQUISITES
  • Understanding of diffraction grating principles
  • Familiarity with photographic techniques and film types
  • Knowledge of optical resolution and spatial frequency
  • Experience with light sources and their effects on photography
NEXT STEPS
  • Research the use of CD and DVD surfaces as diffraction gratings
  • Learn about the optical properties of Kodak 349F film and its alternatives
  • Explore advanced photographic techniques for capturing high-resolution images
  • Investigate the effects of lighting on photographic clarity and diffraction patterns
USEFUL FOR

Photographers, optical engineers, and hobbyists interested in creating and analyzing diffraction gratings for scientific or artistic purposes.

Paddyster
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Hi,
I recently tried to create diffraction gratings using the negative film of a disposable camera. I designed them so the 'slits' were black and the rest was white so on the negative film the slits would be transparent and the rest would be opaque. It didn't work however. Does anybody have any tips on how to make this work?
Kind regards, Patrick.
 
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Paddyster said:
Hi,
I recently tried to create diffraction gratings using the negative film of a disposable camera. I designed them so the 'slits' were black and the rest was white so on the negative film the slits would be transparent and the rest would be opaque. It didn't work however. Does anybody have any tips on how to make this work?
Kind regards, Patrick.
Photographic techniques work pretty well for producing some fine structures like integrated circuits. You say it didn't work but what were your results like?
The quality of the optics is relevant to image quality. Were your pictures well focussed? What was the grating design you were aiming at and what did the stripes on your film look like under a powerful lens? Colour film has a layer of 0.1mm or more.
 
results didn't work at all, I think the problem was I took the pictures too close with the flash on so there was a lot of glare and what not. Do you think if I done them again with no flash they would work? I don't know how focussed they were as I only got the negatives printed, the camera says stand 1m away for it to be fully focused but if i do that i get more than my diffraction grating design in the lens' sight. Would you recommend blowing the designs up so I can stand 1m away and only get that in?
 
Do you mean that you couldn't get a picture at all?
1. What was your original? Hand drawn or printed, perhaps?
2. Did you do some scale calculation, to find whet pitch to expect for the photographic grating?

It is quite a business to get a good photo of a flat image that needs to have exact proportions. Flash is a bad idea and multiple light sources placed around the original will avoid specular reflections. If you want to get a good result, the setup below would be ideal. Having the camera too near to the original can easily produce distortion and the grating would not have parallel lines.
26.jpg

Not easy, I'm afraid.
I suggest that you could try part of the surface of a CD or DVD as a good grating. People here on PF have reported some very convincing results.
 

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Paddyster said:
Hi,
I recently tried to create diffraction gratings using the negative film of a disposable camera. I designed them so the 'slits' were black and the rest was white so on the negative film the slits would be transparent and the rest would be opaque. It didn't work however. Does anybody have any tips on how to make this work?
Kind regards, Patrick.

It's not simple; did you inspect the developed negative to see what the structure looked like?

I've used a similar test target to evaluate microscope objectives, this is a piece of exposed film-

https://www.edmundoptics.com/test-targets/resolution-test-targets/sinusoidal-targets/

Not sure how they were fabricated.
 
It's been a long time since I did this but I used a laser and two separate paths combined to get the diffraction pattern. I exposed a plate of Kodak 349F, which has a spatial frequency of thousands of cycles per millimetre. I guess 349F is long gone but I made lots of gratings this way.

Cheers
 
cosmik debris said:
It's been a long time since I did this but I used a laser and two separate paths combined to get the diffraction pattern. I exposed a plate of Kodak 349F, which has a spatial frequency of thousands of cycles per millimetre. I guess 349F is long gone but I made lots of gratings this way.

Cheers
The film stock in a disposable camera doesn't support that sort of resolution. it will have a coarse grain and a high enough ISO speed to make up for a lens that's like the proverbial 'sucked boiled sweet'.
 

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