RGB white laser for holography?

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warrencat2015
Posts: 3
Joined: Thu Nov 04, 2021 11:30 am

RGB white laser for holography?

Post by warrencat2015 » Thu Nov 04, 2021 12:43 pm

I want to make reflection holograms from long distances away (10ft?) in rgb color. I need a powerful RGB laser.

https://www.laserlands.net/diode-laser- ... odule.html

I want to get the "1w" version of this. I want to use a microscope objective as my diverging lens, I am not sure what would be the best option. I know you can change the multiplication and make the hologram come out more or less life sized but I dont know much about that. I need to read into it more.

It has a red laser 180mw, green 180mw and blue 650mw. I dont know why the blue is that powerful. I dont know if the laser is a TEM00, its probably not. I dont know if it matters that much. I think the temp regulation is already built in.

I am going to use Lippmann plate recipe for the exposure. They are more or less the same thing as holographic plates (just thinner, slower?) and I wanted to try Lippmann too. I figure maybe the thinner emulsion will work better to let more light through to the object? I dont know

lobaz
Posts: 280
Joined: Mon Jan 12, 2015 6:08 am
Location: Pilsen, Czech Republic

Re: RGB white laser for holography?

Post by lobaz » Fri Nov 05, 2021 10:59 am

Hi,
I'm 99.9% positive these lasers are not suitable for holography, at least without considerable effort. Lasers for holography must be strictly single wavelength (so called single longitudinal mode, SLM), while most lasers are far from that. The result of using non-holographic lasers is extremely limited depth of holograms, down to few micrometers.
If you need 1W lasers for holography, be prepared to pay about 30000 USD, perhaps a bit less for second hand equipment.

Petr

warrencat2015
Posts: 3
Joined: Thu Nov 04, 2021 11:30 am

Re: RGB white laser for holography?

Post by warrencat2015 » Thu Nov 11, 2021 10:05 am

Yeah I feared that would be the case. However, I have seen the usage of diode lasers in a similar setup to produce color holograms on the litiholo plates. They are photopolymer, I do not know the grain size. Hopefully comparable to lippman plates, because that means they would work. I will contact their email and ask them I suppose.

I do not have that much money and I probably wont have that much for a considerable amount of time. I am in Northern Kentucky, if there is anybody with such lasers I wish to borrow yours :(

warrencat2015
Posts: 3
Joined: Thu Nov 04, 2021 11:30 am

Re: RGB white laser for holography?

Post by warrencat2015 » Thu Nov 11, 2021 10:58 am

I received the email "Take a look at a recent Youtube video by Thought Emporium that uses our hologram film and diode lasers to make full-color holograms. No issues with grain size for reflection holograms (lippman), and the material is full-color sensitive. Diode lasers do work, but not all diode lasers work for holograms (stability, coherence length, multi-mode, etc). So it is often a bit of trial and error. "

I think if he did it, I probably will be able to.

lobaz
Posts: 280
Joined: Mon Jan 12, 2015 6:08 am
Location: Pilsen, Czech Republic

Re: RGB white laser for holography?

Post by lobaz » Sat Nov 13, 2021 9:32 am

Hi,
a few notes. The term "grain size" applies just to silver halide material, as there are grains of silver halide (often abbreviated AgX) dispersed in the gelatin layer. Materials such as photopolymer do not have any grains of anything like that. This results to an important fact: grainy materials based on AgX tend to scatter light and limit achievable resolution. Both of it limit its usage in holography. Yes, there are AgX emulsions for holography that are very fine grain, but one has to look for one. AgX emulsions for Lipmann photography should be fine grain too, but there is no certainity they will be the best emulsion for holography.

I have very good experience with low power red laser diodes, say up to 10 mW. I was able to make a decent hologram with any of them I ever purchased. I don't have such experience with other colors or higher powers. I know some people succeeded with strong green laser pointers, but I guess they were just lucky they got a good piece and worked in suitable environment.

I would not say it is "trial and error", I'd call it "hit or miss" with high probability of "miss". The problem is that if you are lucky, you don't know about it. If you are not, you have no idea where is the problem -- it may be the laser itself, it may be the power supply, optical setup, weather (no kidding), the object, the photosensitive plate, the development process -- anything.

My recommendation is: If you want to play with a powerful RGR laser, order a few low power modules as well, such as this one:
https://www.laserlands.net/diode-laser- ... 1001a.html

You can start experimenting with the RGB module, but I recommend to start with the low power one. Unscrew the collimating lens (use pliers and a vice), power it from common batteries and make a simple reflection (Denisyuk) hologram of a coin in contact with the plate. If you don't succeed, you can try another laser module (that's why I recommend to get more than one). If you still don't succeed, ask for advice as this **should** work.

Well, and if you succeed, proceed slowly by replacing the components in the setup one by one. For example, you plan to use a microscope objective to widen the beam. Thus, you should use a low-power red module with the collimating lens attached (because you know that it works) and observe whether an objective ruins the setup, or not.

One more last thought. It is not very difficult to make your first simple hologram as a proof of concept. It will be most probably small, of a small object, monochromatic, and not very bright. However, making a high quality large RGB hologram -- that's a very different story. It is not very hard to learn how to ride a bicycle -- but qualifying for Tour de France is, well, a long process.

---

By the way, you have mentioned you want to make "reflection holograms from long distances away (10ft?) in rgb color". Could you make a sketch? I am not sure I understand. If you want to make a reflection hologram of an object located 10ft from the plate, you are out of luck even with the best equipment.

Din
Posts: 333
Joined: Thu Mar 12, 2015 4:47 pm

Re: RGB white laser for holography?

Post by Din » Sat Nov 13, 2021 9:49 am

I would add, start with a negative lens (bi-concave lens) to diverge the beam. You won't get a lot of divergence, not as much as an objective, but enough to shoot a coin in contact with the plate. Negative lenses are a lot cheaper - you can get one from Edmund Optics for about $20 - and a lot easier to align.

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