Introductions

Holography related topics.
Din
Posts: 259
Joined: Thu Mar 12, 2015 4:47 pm

Re: Introductions

Post by Din » Thu Feb 04, 2016 2:42 pm

Well, as a dcg holographer, let me say that dcg is like walking on a shaky bridge while juggling five balls! As I mentioned (and Petr also re-iterated) there are many failure modes in holography: motion, air currents, etc. For dcg, you're making your own emulsion, so you have to multiply the failure modes of conventional holography with the failure modes of coating dcg and developing it.

Let me not discourage you from trying, however, be aware. What you're trying to do is to read about driving a car, never having driven one, then getting a fast sportscar and driving it on a freeway. So, proceed with caution. I agree with Petr that you should start with Ag., In fact, I think it may behoove you to get the kit from Integraf.

Insofar as making dcg's on concrete floors, we did it at the first PCCG. That may be where read about it. John brought the plates (roughly 2" x 2" or 50mm x 50mm, if memory serves) , Danny brought the laser - a solid state 532, I think - and I brought the model. We literally set it up on the floor with the plate above it and zapped it for about 2 minutes. John then developed it. So, it is possible. But I've been doing dcg holography since the 80's, John had coated quite a few plates and got the technique down, and, while he was processing I was watching to make sure we were optimising the development procedure. So, it was a team effort with a wide knowledge base. Doing it just from written material, I think you'll find that troubleshooting the hologram will be challenging.

But, if I may air my personal philosophy: If you don't throws the dice, you ain't gonna win nuthin'. I made my first hologram without having any clue what "exposure" meant!

So, good luck!
lobaz wrote:A DCG plate has sensitivity about 2.5x10^5 uJ / cm^2.
True for HOEs. Not true for display. For display, generally, the exposure is ~ 50 - 70mW. Of course, it's very lambda dependant. Here's the absorption curves for dcg:
dcg-lamda.jpg
dcg-lamda.jpg (38.26 KiB) Viewed 8139 times

pluto
Posts: 97
Joined: Fri Feb 05, 2016 2:06 am

Re: Introductions

Post by pluto » Fri Feb 05, 2016 2:29 am

Hello (again) all! My former account was "hologram" -- I decided to ditch the awfully unimaginative username while I was still relatively new :)

John Klayer
Posts: 271
Joined: Thu Jan 08, 2015 2:28 am

Re: Introductions

Post by John Klayer » Sat Feb 06, 2016 9:10 am

Pluto, why not simply use your real name?

pluto
Posts: 97
Joined: Fri Feb 05, 2016 2:06 am

Re: Introductions

Post by pluto » Sat Feb 06, 2016 12:31 pm

John Klayer wrote:Pluto, why not simply use your real name?
Maybe Pluto is my real name! Haha, no, just privacy concerns.

Wackhaus
Posts: 38
Joined: Sat Feb 13, 2016 3:45 pm

Re: Introductions

Post by Wackhaus » Sat Feb 13, 2016 4:53 pm

Hey guys whats up :)
SO- im new,i started out over the summer at dr lasers in the city and i just never left.. and now i make them at home at night, i snatched up like 3 different kits off of ebay just so i could get as many plates as i could to practice on, and ive been pretty happy making weird little holograms and testing out my materials and playing with light and seekng the way it acts, and im reading up on optics and lasers and photonics, and im really pretty psyched i found this forum :)
(And it looks fairly active, which i great i really miss messageboards
pocket full of holograms

lobaz
Posts: 272
Joined: Mon Jan 12, 2015 6:08 am
Location: Pilsen, Czech Republic

Re: Introductions

Post by lobaz » Sun Feb 14, 2016 4:31 am

Hello, Wackhaus, and welcome to the forum. What sort of kits are you talking about? I know just Integraf and Litiholo kits - did you find anything else? By the way, you can add chemistry and mechanics to your list of books to read. :)

Wackhaus
Posts: 38
Joined: Sat Feb 13, 2016 3:45 pm

Re: Introductions

Post by Wackhaus » Sun Feb 14, 2016 2:00 pm

Also metrologic :lol:
Im loving the integraf, i cant make ANYTHING with the liti plates. Theyre from 2004, and ive been told to push the exposure time +10 minutes and at this point i dont even think of using it anymore. I havent checked the film on the metrologic yet, it was opened so im just hoping it wasnt exposed
pocket full of holograms

lobaz
Posts: 272
Joined: Mon Jan 12, 2015 6:08 am
Location: Pilsen, Czech Republic

Re: Introductions

Post by lobaz » Tue Feb 16, 2016 3:31 pm

Thanks, I did not know metrologic kit! Looks nice.
Liti plates require very long exposure times. Set up everything in a very calm environment (like in the basement in the night) and try a reflection hologram of e.g. screws glued to a base with the plate directly lying on them. Expose for about 20-30 minutes with Litiholo kit laser diode. It is almost impossible to overexpose them, but easy to underexpose! :)

pluto
Posts: 97
Joined: Fri Feb 05, 2016 2:06 am

Re: Introductions

Post by pluto » Wed Feb 24, 2016 3:21 pm

Din wrote:Well, as a dcg holographer, let me say that dcg is like walking on a shaky bridge while juggling five balls! As I mentioned (and Petr also re-iterated) there are many failure modes in holography: motion, air currents, etc. For dcg, you're making your own emulsion, so you have to multiply the failure modes of conventional holography with the failure modes of coating dcg and developing it.

Let me not discourage you from trying, however, be aware. What you're trying to do is to read about driving a car, never having driven one, then getting a fast sportscar and driving it on a freeway. So, proceed with caution. I agree with Petr that you should start with Ag., In fact, I think it may behoove you to get the kit from Integraf.
I just wanted to follow up on my DCG progress.

It was actually much easier than I thought to produce DCG holograms! Besides the cost of the initial investment (stable green lasers can be pricey), I don't understand why one wouldn't start with DCG, in fact.

I spent an evening mounting my laser on a heatsink and an evening making the emulsion and doing the exposures -- I made a hologram the same day! And this is with a very simple setup -- no vibration isolation, optical table or even optical mounts. I should post a picture of my setup when I get home.

It wasn't the prettiest, but that was largely due to sloppy coating of the glass plates. I've made a couple since and they look quite good where the emulsion was the right thickness.

Also the ingredients for the emulsion are dirt cheap. You can produce many plates in batch and be set for many dozens of exposures then refridgerate the excess.

This is for single beam reflection anyway. I would definitely recommend DCG to beginners unless they just want to produce a handful of holograms. Spend your money on a good laser rather than an Integraf kit, IMO. I don't know much about MBDCG, but you could possibly even do DCG holography with the cheaper red lasers.

Anyway, I'm finished extolling the virtues of DCG now :)

Din
Posts: 259
Joined: Thu Mar 12, 2015 4:47 pm

Re: Introductions

Post by Din » Wed Feb 24, 2016 5:42 pm

Glad to see this level of excitement!

I made my first hologram in 1982. We had a family town house in a village called Hindhead, about 40 miles from London. This house had a garden with a view of the main London road, or rather, anyone driving to London had a great view of the garden. I bring this up because, like you (but without the benefit of the internet), I had to pretty much figure most of it out by myself. Anyway, I finally finished a shot at 3 in the morning, propped the hologram by the bedside lamp and went to sleep. The next morning I thought I saw something in the glass (it was a porcelain bear, about 2 inches tall). So I grabbed a bathrobe and rushed down to the garden, for the sun. So, there was a hologram! A real, 2 in tall, red bear, by god! I had a grin a mile wide. Then I looked up and saw the rush hour London-bound traffic. All those drivers, stuck in a traffic jam, all looking at this idiot with a bathrobe and a big idiotic grin staring at a small, empty glass rectangle! I resisted the temptation to go running up to the drivers and say, "Look! Look! Hologram!"

But, as I said earlier, it's easy to make a hologram. It's a little more diffcult to make a good hologram. I say this because you're excited that you got a hologram because you didn't think you'd get one on your first attempt. Now comes the hard part. You've got to figure out emulsion depth, processing, uniform coating, lighting etc etc.
pluto wrote:I don't understand why one wouldn't start with DCG, in fact.
Because you don't have to worry about coating issues, for one, and you can get a range of colours relatively easily. Colour tuning with dcg ain't easy. Another issue is that dichromate is not a good substance to mess with. I'm not sure what the situation is in Canada, but I believe you can't buy dichromate in some parts of Europe. Here in the USA, I had to fill out a form stating why I wanted it, for the first time since starting Triple Take Holographics in 1999.
But again:

Keep calm and shoot holos

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