Safelighting

[Howie]

Hi,

I JUST got done developing my first 4 holograms and can't wait to see what they look like when they dry.

One thing that I'm unsure of though is what is considered acceptably low light levels. I don't have a safelight so I manipulated lights in other rooms till I could just BARELY see what I was doing, and went with that.

I've read you want the light low enough that you can't read, and I certainly was at, or below that level. Are people using the green lights though to be able to see and if so, do they really need to be the purpose built lights I've seen at B&H and places like that?

Anyhow, thanks for the tips and links and hopefully I can get something work looking at. I have 30- 2.5"x2.5" and 6- 4"x5" PFG-03M plates and hopefully I can get some good ones.

[laston]

Search for "safelight" in the old holography forum archives http://holoforum.org/oldforum/

PFG-03M is sensitive to red and relatively insensitive to green.
You can use green LEDs as safelight, or even a diffused 532nm laser beam.

[Jem]

Hi Howie

Don't forget to post some pic's of your hologram(s) when you get them finished. It is worth a search of the old forums as there is loads of useful information there. However, most holography film doesn't appear to be hyper sensitive to ordinary white light, if you keep the light as low as you can manage you'll probably get away with it.

However, I wouldn't particularly recommend this method as it's not worth risking fogging a batch of film. Do you have an old green laser kicking around the place?, that would make an ideal safelight for the film you're using.

[Howie]

Thanks for the tips. I could swear the archives of the old holography forum weren't up last time I looked but it's been a while. I'll definitely have to dig into that!

Of the 4 I made the other day, two are hardly visible at all and two turned out much better. I have a video of the two "good" ones I'm trying to upload and I'll post the link.
The two that didn't turn out some seashells and a couple little glass balls.

I just did 4 more and upped the exposure from ~10 seconds to ~15. I'm not sure if that will brighten them up at all but we'll see if there is any difference. Also, I made these vertically which made it a little easier to get the object right in the center of the light. I did use a single green led pointed away from where I was doing the exposure to give me just a hint of light to see what I'm doing. The only green laser I have is my RPL-260 which is way too much I think.

This is the video. I shot the video with my phone so it's not the best quality but it should give an idea of what they look like.
http://www.youtube.com/watch?v=-9eADxy4GO4

[Jem]

Hey, nice work , those look really good.

[Howie]

Thanks Jem, they're a lot of fun.

I made a few more last night and one turned out a lot better I think. I'm still having 50% failures where there is no image at all but that's to be expected I think.

Now if I can just get the elusive seashells to show up...

[Jem]

That's great, i'm pleased you're having some success. With regard to your failures, is your setup stable enough? If you're making single beam reflection holograms it's best to have your plate leaning against, or supported by, the object. What you need to avoid is any movement between the object relative to the plate. By placing the plate against the object the chances of movement are minimised. However, you still need to make sure you've got a reasonably stable base such as a paving slab etc.

If vibration is a problem you could mount the slab on a partially inflated car innertube and place it on a concrete floor etc. I've had horrendous problems overcoming stability issues and cannot stress enough how important stability is for obtaining decent holograms. Don't forget to allow plenty of settling time.

Keep up the good work

Cheers

Jem

[laston]

.... The only green laser I have is my RPL-260 which is way too much I think......

Hello Howie,
Did you make the holograms with the RPL-260?
Are your holograms banded, e.g. do they show lines across the image?
It would be a great surprise if a small laser like this is single mode and stable enough to be used for holography.

[Howie]

Jem, my setup isn't close to ideal for sure. I'm working on my dining room table which has a glass top. For the first ones, I folded a blanket on top of the table then placed another glass end table top on top of that. I have the plate and object in contact and once I set the plate, I let it settle for about a minute, then expose. This will be the first area of improvement that will probably yield some positive results.

laston, I haven't tried the RPL-260 because I don't think it's slm. I'm using the little module that came with the Integraf kit. I don't see any banding on the ones that have turned out. I either get an image, or not. It's likely the stability of my setup that is at fault. I'll have to try and get the specs for the RPL now that you mention it and see if it would be useful for holography.

[holokidd]

Helo howie, your settling time is way to short. you should wait at least 10 minuets or more ...