How to create diffraction gratings from negative film

In summary, Patrick tried to make a diffraction grating using the negative film of a disposable camera, but the results were not successful. He suggests trying a CD or DVD as a test target, but it's not easy.
  • #1
Paddyster
6
0
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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  • #2
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.
 
  • #3
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?
 
  • #4
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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  • #5
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.
 
  • #7
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
 
  • #8
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'.
 

What are diffraction gratings and how are they created?

Diffraction gratings are optical devices that consist of a series of parallel lines or grooves etched onto a surface. They are used to diffract light into its component wavelengths, creating a spectrum. To create diffraction gratings, a common method is to use a negative film with a pattern of lines etched onto it. The film is then placed onto a substrate, such as glass, and coated with a reflective material.

What is the process for creating diffraction gratings from negative film?

To create diffraction gratings from negative film, the film is first developed and washed to remove any residual chemicals. Then, it is dried and placed onto a flat, clean surface. A layer of photoresist material is applied onto the film and exposed to UV light through a mask with the desired grating pattern. The exposed photoresist is then developed and etched, leaving behind the desired grating pattern on the film. The film is then coated with a reflective material and the photoresist is removed, leaving behind the diffraction gratings.

What factors should be considered when creating diffraction gratings from negative film?

Several factors should be considered when creating diffraction gratings from negative film, including the desired grating frequency, the depth of the grooves, and the angle of the grooves. These factors will determine the diffraction angle and the quality of the grating. The type of photoresist and etching process used will also affect the final product.

What are some common applications of diffraction gratings?

Diffraction gratings have a wide range of applications, including in spectroscopy, telecommunications, and laser technology. They are used to analyze the composition of light sources, to separate different wavelengths of light for communication purposes, and to create lasers with specific wavelengths. They can also be used in optical instruments, such as spectrometers and monochromators.

Are there any alternative methods for creating diffraction gratings?

Yes, there are alternative methods for creating diffraction gratings, including direct laser writing, electron beam lithography, and holography. These methods offer greater precision and control over the grating pattern, but they also require more advanced equipment and expertise. The method of using negative film is a more accessible and cost-effective option for creating diffraction gratings.

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