It's time...guidance apppreciated.

[Vaaccess]

Hey everyone. A couple of decades ago I went to the Mall of America and witnessed holograms for he first time. I was blown away.

Since then I had read a couple of hologram books but never had suitable space for the sandbox, etc.

I now live in a house with a cement floor basement and more space so I think it's time I give this hobby a try.

I have middle school aged kids and want to expose them to this awesome science, but moreover I want to make art and gifts for people. I am a techie by day and a serious photography hobbiest.

Ive looked at some of the current kits on the market, but have questions. When I saw the kits where the plate rests against the object, I was highly skeptical. Is it really that simple now!?? Will the quality be good? I love the idea of self-developing plates, are they going to be a good choice? I know pulse lasers are potentially going to change things, should I consider jumping straight to that?

I guess I'd wrap this up by saying...I want this to be a rewarding hobby, but I don't want to start too basic and be frustrated with the results. Can someone confirm that the Standard kit is indeed the right starting point or recommend an alternative path?

So very excited, thanks in advance for your help!

Mike

[Din]

When I saw the kits where the plate rests against the object, I was highly skeptical. Is it really that simple now!?? Will the quality be good?

You seem to be talking about the Liti kit. I've heard mixed reports. Some here on the forum seem to have got good results, while I never did.

The basic issue with holography is stability. As a photographer you're aware that if the subject moves during the exposure, you get a blur. However, in photography, thee exposures are extremely fast, so the issue does not arise. In holography, you're taking a photograph of very, very tiny lines - about 1/100,000 th of an inch and the exposures are in the area of several minutes. In other words, the object of your hologram cannot move by about one hundred thousandth of an inch over a period of several minutes. So, in answer to your question about the quality of simply propping the plate against the object, unless your table is extremely stable, it's unlikely to give good results. The material used by Liti is what's known as a "photopolymer". These materials are very insensitive (in photographic terms, they have an ASA 0.000....) and so require several minutes of exposure. You might want to take a look at the Integraf kit ( http://www.integraf.com/shop/hologram-kits ). These kits use silver halide film and are much faster.

I know pulse lasers are potentially going to change things, should I consider jumping straight to that?

I would say, "no". Pulse holography is a quite a bit different from, and more difficult than, continuous wave holography.

If I may offer a bit of a tutorial, as I mentioned, in holography you're taking a photograph of very, very tiny lines. Also, you're effectively taking this photograph from "inside" the camera. A photographic camera has all the appropriate optics "built into" (or attached onto) the body of the camera and all the "controls" are on the outside. In holography, you lay out all the optics on the table, "free form" as it were, so as to produce appropriate reference and object beams.This means that all the lenses, mirrors etc are also subject to the same stability conditions as the object itself. In other words, all the optics and the subject (including the plate holder) needs to be stable to within 1/100,000 of an inch over several minutes/seconds.

In holography, the exposure is determined by the energy issuing from the laser onto the film, and the film sensitivity. So, for example, if you have a 10 mW laser (this is specified by the manufacturer and laser142 on this forum can advise you about lasers), then by the time the beam has expanded through various lenses etc, you may have about 1 mW of laser power hitting the plate Silver halide film (the standard photographic medium, but very high sensitivity) has a sensitivity of about 0.2 to 0.5 millijoules (mJ), so you need an exposure of about 1/5th to 1/2 seconds. Photopolymer has a sensitivity of several mW (say about 10), so you need an exposure of 10 or more seconds. In a pulse laser, the laser "dumps" a large amount of power very quickly. So, if an object is inherently unstable and cannot be stabilised, such as human skin, then you need exposures of milliseconds to microseconds. In this case, you'd need a pulse laser. But, because of the very short "flash" it's difficult to set up.

Your best bet to start would be to make a stable plate holder, one in which the plate, when inserted, does not rattle, expand the beam to the dimensions of the plate, and place an object behind the plate. The object needs to be also very stable (most people start with a porcelain object such as a porcelain cat - therein lies a joke! - or a brass Buddha) and secured stably. This geometry is called a Single Beam Denisyuk.

Processing the film is whole another talent. But Alex Jeong, owner of Integraf is pretty responsive on helping with the kit.

[jsfisher]

I also recommend the Integraf kit as a starting point. If your intent is to discover how interesting a hobby in holography can be, the Integraf kit will get you involved; the Liti kit has you snap a few plastic parts together then flip a switch. Either way, you'll probably end up with at least one (probably dim) result you can show others by the time you burn through all the plates in the kit, but only with the Integraf kit will you have ideas of how you'd like to experiment with more plates.

Oh, don't get the "Budget Kit". For your first attempts, go with glass plates, not film. I'd recommend the "Standard Kit"; you'll have far more fun with 30 plates than with 12.

[Vaaccess]

Thanks to both of you for your replies!

In holography, the exposure is determined by the energy issuing from the laser onto the film, and the film sensitivity.

Precisely one of the things I was hoping to get more feedback on. Specifically, while I know the kits come with a specific laser, should I consider bumping up a level higher? When I started doing photography I splurged on nice, fast glass. And it has paid off over the years. I'm wondering if the same type of thing might exist in holography, in that a minor upgrade in cost to a more expensive laser (or more sensitive plates/film) wouldn't yield a better experience out of the gate since the end-result would be better and less frustrating.

However, it's also very possible that the cost of entry for the "next step up" might be too high to consider.

So let me ask it this way...Knowing that the integraf kit is a strong entry point, what would be my next step up from a laser/film/plate perspective?

On the processing of the film/plates...That'll be new to me, but fortunately my wife has processed film before so hopefully that will help! I do have an inner laundry room with a sink that will hopefully be a good candidate to process everything.

Thanks again for your responses and all of your other comments as well.

Mike

[Din]

I think that a higher power laser is probably the way to go, assuming you want to invest in holography. As for more sensitive plates, silver is already the most sensitive material out there. What you have to consider is the type of hologram you want to make.

First, the laser: THE most important thing (and I capitalise to stress) is stability in your system. If any component of your system moves by about half a wavelength (the 1/100,000 th of an inch i mentioned above), you won't get a hologram. However, all systems will move sooner or later, if only because of thermal currents as the day wears on from day to night or vice versa, you walking about the room etc. So, the most important thing is to keep the exposures as short as you can. If your system does not move by half lambda over the period of your exposure, you'll get a good hologram, (all other things considered). So, the shorter the exposure, the less the motion problem.

If you want to make a white light viewable hologram (that is, one that can be seen in normal light, as opposed to laser light), then you need to make a reflection hologram, usually most people start with a single beam Denisyuk, as i explained above. But, a Denisyuk has more stringent stability requirements and needs a longer exposure. If you make a laser viewable, transmission hologram, only viewable by laser light, the exposure is shorter and the motion less stringent. The disavantage of laser viewable holograms is that you can't show it to anyone else unless they have a laser, the advantage is that it's a good way to "get your feet wet" because it requires less stability and less exposure. However, if you go this route, sooner or later you'll want to make a white light viewable hologram. So, once again, a more powerful laser is probably a good idea to start. Also be sure that the laser is single mode TEM00. I'd ask Laser142 for help on this (Phil?)

On the processing of the film/plates...That'll be new to me, but fortunately my wife has processed film before so hopefully that will help! I do have an inner laundry room with a sink that will hopefully be a good candidate to process everything.

The thing about processing is that it's really a sort of intuitive ability that people develop. There are general "rules". First off Alec Jeong sells a two-part developer (JD-something -or-other) that needs to be mixed just prior to developing. You place the plate in the developer tray and rock gently. The plate needs to go roughly about "90% dark" in about 3 minutes. That means that you need a safelight, and as it develops, you need to look at the safelight through the (developed) hologram. If the (developed) hologram cuts out about 90% of it's light in about three minutes, your exposure is probably OK. If it goes 90% dark in less than a minute or so, you've overexposed, and if it doesn't go after about 6 minutes, you've underexposed. So, you need to do exposure tests. The "standard" method is to make a mask that covers about 1/3 of your plate, expose 1/3 of your plate, move the mask and expose the next section by a bit more. It's difficult to say what the initial exposure should be, but with a 2"x2" plate, the power will be about 1/2 to 1/4 of the laser power (depending on your optics) , so you can calculate the exposure from the film sensitivity. Generally speaking, the film Alec sells has a sensitivity of about 200 - 300 mJ. So, a 1 mW laser will give you about 250 - 500 uW at the plate. This translates to about a 1 second exposure. Basically, the power of the laser tells you how many photons are being thrown out by the laser/second. The sensitivity of the film tells you how many photons the plate needs before good fringes start to appear.

After this, you need to bleach. You make up the bleach solution as per instructions. After the developer stage, you wash the plate in water for about a minute or two. You then place the film in the bleach and rock gently. It should start to go clear in about a minute or two. Once it clears, leave it in for another 30 seconds ("clear + 30"). Then wash again for about 5 minutes. At this point, you can put it in some Photoflo for a few seconds. You can now dry it with a hair dryer, if you're really impatient and take a look. If you do this, put it back in the wash. The hair dryer reticulates the emulsion.

Here's somethig I wrote about silver halide emulsions in the wiki: http://holowiki.org/wiki/Silver_Halide_Materials

By the way, there's a lot of information on this wiki, so I'd suggest looking around at it.

[Ed Wesly]

You would be better served looking at these links:

http://edweslystudio.com/Pedagogy/TS/Te ... meset.html on how to do test strips.

These for a discussion of the processing steps: http://edweslystudio.com/Formulae/Developers/PYROAB.pdf; http://edweslystudio.com/Formulae/Developers/CWC2g.pdf;

The Integraf/Photographers’ Formulary kits JD-2 and JD-3 are the CWC2 developer, with either a reversal bleach or rehalogenating bleach, respectively. JD-4 is a stronger brew, suitable for the Slavich PFG-03M or PFG-03C emulsions, or the Harman Technology/Ilford HoloFx plates.

And of course explore the full web site, http://edweslystudio.com

My vote is to start with the Integraf kit.

[Colin Kaminski]

I am glad you put together a web site Ed. I can't wait to look through it. The Integraf kit is my vote too.