Focus and Perspective

Lots has changed in the dozen years since my last time here, and I'm thinking it's a good time to step in again. My intent is to focus on old laser issues (which are sparse) and laser history, and comment only from the perspective of a professional holographer of forty years.

Yep, grampa's lasers (things of the past).

And real holograms (things of the future).

Welcome back to the forums!

What was your previous account?

Is this you?

Yeah, that's me. Here's the article.

Welcome back! Great to have you here again to share your knowledge.

I recently pushed my record for my oldest working laser back a few years.
I just got three working SP-155, from 1976-77, with the oldest being Sep 1976. Surprisingly all were working, though they don't light up consistently.

I've decided to let one of my first holographic images to represent me here. His name is "Boris". I made the 4x5" image-planed reflection hologram in 1984 with an anonymous sculpture received as a gift, and sold a few hundred of them in the following few years. The "master" was an 8x10" transmission hologram in Agfa silver-halide material (as were the transfers), both made with a Spectra-Physics model 124 15mW He-Ne laser. He plane of the hologram goes through his ears.

How do you make a hologram out of a real object?

Best way is transmission holography.

Hi!

I'm relatively new to holography. I've made a handful of decent ones myself with red diode lasers and red HeNe. I'd really love to be able to make some green holograms, but I can't seem to find a complete OPSL or acceptable green diode/DPSS laser for holography. I'd love to hear any recommendations. Ultimately, I'm wanting to make something that records both red and green wavelengths to make a sort of bicolour hologram, but first things first.

I would also love to get into deep-field holography, if possible without an overly large HeNe tube. The only holograms I've had turn out decently were only 2-3 cm deep.

Probably the best to use would be a 543nm HeNe.

Unown (WILD) said:

How do you make a hologram out of a real object?

Click to expand...

Too many ways to do that to describe here, but the drawing above shows one. Another (invented by Yuri Denisyuk, who also taught me to drink shots off my elbow) is to lay a plate with recording material on it on top of the object, and illuminate the whole scene with a diverged beam from a laser operating in a single mode for the proper exposure. Diode lasers can sometimes operate single mode when just above threshold current. Look for interference fringes in the reflected spots off a glass window in the expanded beam to identify if and when this happens with your laser.

bostjan said:

Hi!

I'm relatively new to holography. I've made a handful of decent ones myself with red diode lasers and red HeNe. I'd really love to be able to make some green holograms, but I can't seem to find a complete OPSL or acceptable green diode/DPSS laser for holography. I'd love to hear any recommendations. Ultimately, I'm wanting to make something that records both red and green wavelengths to make a sort of bicolour hologram, but first things first.

I would also love to get into deep-field holography, if possible without an overly large HeNe tube. The only holograms I've had turn out decently were only 2-3 cm deep.

Click to expand...

Use silver-halide film instead of the easier photopolymer (like from Liti) and you'll be able to use much, much lower powered lasers. Processing is simple with chemicals from Photographer's Formulary, and can be done easily in a bathroom.

Bicolor holograms can also be made with "pseudocolor" techniques. A common one is to use a red laser for a first red exposure, then swell the recording material with triethanolamine, dry and clean the plate and put it back into the plateholder, then do a second exposure also with the red laser. The image from the first exposure will be red after processing. The second exposure will be green after the triethanolamine washes out. I'm leaving out a few fine details, but the technique was used a lot in the '80s.

You may consider visiting Southwood Holographics in Germantown, NY. They have resources for lots of holography of all sizes, have programs for educational and artistic explorations, and it's run by Oscar-winning cinematographer Hart Perry.