Why does the use of photopolymer film produce ripples?
Why does the use of photopolymer film produce ripples?
Why is the brightness distribution uneven, usually bright at a certain point
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The subject is Spider-Man's spiderweb gesture.
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Re: Why does the use of photopolymer film produce ripples?
Looks like your laser has a low coherence length. I would suggest trying a laser with a single longitudinal mode.
Re: Why does the use of photopolymer film produce ripples?
Hello, this is the single longitudinal mode coherent laser used, coherence length 50m



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Re: Why does the use of photopolymer film produce ripples?
It doesn't look like a coherence problem. When that happens, there are contour fringes (light and dark bands across the image of the object). This corresponds to the coherence length going in and out throughout the depth of the scene. In the photo, it looks like the bands are going across the plane of the film (two-dimensionally). I can't say what the problem is, but sometimes stray light can enter the side of the glass plate (or glass carrier plate in the case of photopolymer) and cause odd effects. Another possibility (probably more likely) is that, if you're not using Brewster's angle with the correct polarization of your laser (to minimize internal reflections), light could be bouncing around inside the glass, which can also cause bands in the hologram.
Also, I saw something strange the other day when doing an exposure using Bayfol with a 1-watt green laser. It looked like the film itself was moving as the exposure was being done. The film looked "alive" with horizontal stripes during the exposure. It was extremely odd, I've never seen anything like that before. The hologram still came out, but there were fuzzy horizontal bands across the final hologram. I have no idea what was happening.
Re: Why does the use of photopolymer film produce ripples?
Light going in from the edge looks different and produces relatively straight lines that don't go that far across the plate. This looks like interference fringes. If you have access to a scanning interferometer, I'd check the laser. It may not be operating properly. Or try to make a hologram of a ceramic object.
Re: Why does the use of photopolymer film produce ripples?
My first instinct was woodgrain - the lines that come up if the wrong polarisation is used at Brewsters, or it's at the wrong angle; the lines are formed by bouncing around inside the material, But, the lines are too closely set together, implying the angle is pretty low. Assuming this is woodgrain, the reference angle, θ, is given by:
θ = arctan(s/(2d))
where s is the line separation, d is the thickness of the glass. Carrying out the calculation using reasonable figures, makes the reference angle to be about 10 deg, which is unlikely for a display hologram.
I don't think it's light creeping in from the edges, again because the spacing - the spatial frequency - is too high. The light would have to penetrate at about 10 deg.
I also don't think it's an interference pattern because to make an interference lines that are parallel with this relatively high spatial frequency would require two plane (collimated) beams. If one beam was diverging/converging, the spatial frequency would vary.
So, I was a little lost. I showed this to Joy, and she, at once, said "Film motion". She pointed out that the lines went beyond the image; had it been object motion, the lines would have been on the image. This would explain the high-ish spatial frequency, if the film/glass were bowed because of stresses in holding the film. If the film were pinched between clips, for example, and there was dust underneath one clip, the film would bow. Also, if the clips were different strengths, it would place stress on the film. At any rate, if the film was stressed, and tried to slowly return to being flat during exposure, it would cause just this type of fringing. The high spatial frequency is explained by the fact that there probably was not too much bowing, and the regularity of the fringes would be explained by the fact that the bowing was circular.
So, it depends on how the film was secured during exposure.
θ = arctan(s/(2d))
where s is the line separation, d is the thickness of the glass. Carrying out the calculation using reasonable figures, makes the reference angle to be about 10 deg, which is unlikely for a display hologram.
I don't think it's light creeping in from the edges, again because the spacing - the spatial frequency - is too high. The light would have to penetrate at about 10 deg.
I also don't think it's an interference pattern because to make an interference lines that are parallel with this relatively high spatial frequency would require two plane (collimated) beams. If one beam was diverging/converging, the spatial frequency would vary.
So, I was a little lost. I showed this to Joy, and she, at once, said "Film motion". She pointed out that the lines went beyond the image; had it been object motion, the lines would have been on the image. This would explain the high-ish spatial frequency, if the film/glass were bowed because of stresses in holding the film. If the film were pinched between clips, for example, and there was dust underneath one clip, the film would bow. Also, if the clips were different strengths, it would place stress on the film. At any rate, if the film was stressed, and tried to slowly return to being flat during exposure, it would cause just this type of fringing. The high spatial frequency is explained by the fact that there probably was not too much bowing, and the regularity of the fringes would be explained by the fact that the bowing was circular.
So, it depends on how the film was secured during exposure.
Re: Why does the use of photopolymer film produce ripples?
Plate motion wouldn't cause fringes like that, in my experience. Fringes caused by the plate being under stress during exposure would not have regular spacing, and certainly not across the whole plate. I can't even think of a way to make a plate move that would cause such fringes. Also, the fringes are not straight lines. While I've not seen this pattern before, I 'd still recommend a coherence length check on the laser used, or trying a different laser.
If it's the laser, all exposures would generally have the same issue. Fringes caused by plate motion would be different for each exposure. Same with object motion.
If it's the laser, all exposures would generally have the same issue. Fringes caused by plate motion would be different for each exposure. Same with object motion.
Re: Why does the use of photopolymer film produce ripples?
Previously, our company sold photosensitive polymer film to a private enterprise, which also encountered similar problems during its use. After communication and adjustment on WhatsApp, our factory specially configured a new coating solution based on his situation, and they successfully solved the problem.
The general problem lies in:
1. There are occasional noises around the environment, such as the honking of cars near the highway;
2. Vibration caused by the presence of vibration ripples, as small businesses find it difficult to have large metal workbenches;
3. Insufficient laser power and exposure time result in unstable and attenuated images.
The above is for reference, hoping it will be helpful to you. I am Uky, the business manager, and my explanations may not be professional. If you need more help, you can add me on WhatsApp+86 189 7939 8198, and I can ask the professor from the research institute to help answer it!
We are Chinama Optoelectronics Technology Group, specializing in the research and development, design, production, export of holographic optoelectronic components and industrial products! For example, the quality and price of photosensitive polymer film and silver halide glass are comparable to Litiholo, Geola,Integrat, When the country is similar, we will continue to research and optimize, reduce costs, optimize prices, and provide unlimited supply. We welcome customized procurement!
The general problem lies in:
1. There are occasional noises around the environment, such as the honking of cars near the highway;
2. Vibration caused by the presence of vibration ripples, as small businesses find it difficult to have large metal workbenches;
3. Insufficient laser power and exposure time result in unstable and attenuated images.
The above is for reference, hoping it will be helpful to you. I am Uky, the business manager, and my explanations may not be professional. If you need more help, you can add me on WhatsApp+86 189 7939 8198, and I can ask the professor from the research institute to help answer it!
We are Chinama Optoelectronics Technology Group, specializing in the research and development, design, production, export of holographic optoelectronic components and industrial products! For example, the quality and price of photosensitive polymer film and silver halide glass are comparable to Litiholo, Geola,Integrat, When the country is similar, we will continue to research and optimize, reduce costs, optimize prices, and provide unlimited supply. We welcome customized procurement!
Re: Why does the use of photopolymer film produce ripples?
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