Results of color tests

Dinesh · Post by **Dinesh** » Tue Nov 02, 2004 5:50 pm

As I mentioned elsewhere, I spent last week playing with color.
Here's the first object:

and here's the hologram:

However, I wasn't happy about the rendition, so I went back to basics. Here's a new set of objects:

and here are the holograms:

Ad you can see, the red objects became green and the blue/green became purple. At first I though it was emulsion collapse. So I changed from JD4 to CWC2 (the 2nd pic) and still got green/purple. So then it occurred to me that it was overexposure. So I reduced the red exposure (3rd pic) and the red/yellow objects became red while the blue/green objects remained purple. I then reduced the green exposure (4th pic) and nothing happened!

Most perplexing. Is a puzzlement!
Unfortunately the power supply to the HeNe exploded curtailing any further experimentation.

JohnFP · Post by **JohnFP** » Tue Nov 02, 2004 6:11 pm

hey, the rendition may not be to your liking but I like the multicolors in the first hologram. Flowers and birds come in all colors so it's not obvious that the final hologram colors are not natural. To me, not seeing the original object, the colors look very natural with bright multi colored flowers, dark leaves and dark and light birdie. I like it!!!

Guest · Post by **Guest** » Thu Nov 04, 2004 11:59 pm

Dinesh wrote:So then it occurred to me that it was overexposure. So I reduced the red exposure (3rd pic) and the red/yellow objects became red while the blue/green objects remained purple. I then reduced the green exposure (4th pic) and nothing happened!

Based on those pics, my guess would be still overexposed on both, maybe moreso on the red. The white card holding balls looks like it doesn't quite get to yellow.

I can consistantly get green holograms on PFG-01 when using my Red HeNe by just over-exposing.

Could it be that same mehanism (whatever that is) is being applied to the over exposed green, shifting it closer to blue/purple?

Have you tried red alone and green alone?

Sorry to hear about the power supply! Hopefully your lab doesn't smell like melted platic and PCB's, etc...

Dinesh · Post by **Dinesh** » Fri Nov 05, 2004 2:52 pm

[quote:d9c5790054="LarryD"]

Could it be that same mehanism (whatever that is) is being applied to the over exposed green, shifting it closer to blue/purple?[/quote:d9c5790054]
I thought of that. I reduced the red first and then the green. It didn't take much reduction of the red to get the green back to red. Going just by memory without my notes, I think I had the red at 7 seconds and the green at 15 seconds. I reduced the red to 5 and left the green alone and so got the red image back to red. I then took down the green by stages: 15secs, 12 secs, 10 secs and still the purple persisted. I'd have expected a 30% reduction in exposure to have some effect, but nothing!
[quote:d9c5790054="LarryD"]

Have you tried red alone and green alone?[/quote:d9c5790054]
No. In fact that was going to be my next attempt. I was going to make simple gratings with just red and just green so I could get efficency vs exposure curves for the stuff. One problem with colour holography seems to be that PFG-03C is the only pan material out there and it's incredibly soft and I can't get reliable exposure vs wavelength numbers. I tried Colourholographics BB stuff and I liked that, but so few people are doing colour holograms (

) that Colourholographics is apparently not even producing the stuff and Slavich has to be specially pre-ordered. With so little activity there's no community you can ask questions of.

[quote:d9c5790054="LarryD"]Sorry to hear about the power supply! Hopefully your lab doesn't smell like melted platic and PCB's, etc...

[/quote:d9c5790054]
It actually smelt of burnt carpet all through the weekend.

JohnFP · Post by **JohnFP** » Fri Nov 05, 2004 3:03 pm

This is just my 2 cents but I think you were on the correct path with your first assumption, that is the emulsion is collapsing or shrinking. At least if you swelled the emulsion in the first photo you would get the red ball red and the green ball green. Once you got the red ball red and the green ball green then modifying the relative intesity of both may be helpful. I have a 10 mw HeNe, would you like to borrow it?

DJ Mathson · Post by **DJ Mathson** » Sat Nov 06, 2004 12:11 am

Dinesh wrote:One problem with colour holography seems to be that PFG-03C is the only pan material out there and it's incredibly soft and I can't get reliable exposure vs wavelength numbers.

You also have the Ultimate plates from Yves Gentet.
http://perso.wanadoo.fr/holographie/GB/ ... nglais.htm

Dinesh · Post by **Dinesh** » Sat Nov 06, 2004 2:52 pm

[quote:01821e591c="D J Mathson"]You also have the Ultimate plates from Yves Gentet. [/quote:01821e591c]
I couldn't see any sensitivity vs wavelength figures on their site. Has anyone done color with Ultimate. I I have an Ultimate hologram by Kris Meerlo , but its monocolored. Is Ultimate now producing film?

[quote:01821e591c="JohnFP"] I have a 10 mw HeNe, would you like to borrow it?[/quote:01821e591c]
Thanks, but I'm going to get a new power supply. I don't think the head got damaged. Besides which, I'll be shelving color for a while. Research comes second place to income, unfortunately

.

Guest · Post by **Guest** » Tue Nov 09, 2004 12:38 am

I was lookng at the CIE color chart and your pics and came up with this thought...any chance your argon was outputing more than just the green when you shot the hologram? Specifically also a shorter wavelength like 454nm or whatever lines your laser outputs that are more blue than green?

Dinesh · Post by **Dinesh** » Tue Nov 09, 2004 3:37 am

[quote:69d9bdd0e7="LarryD"]I was lookng at the CIE color chart and your pics and came up with this thought...any chance your argon was outputing more than just the green when you shot the hologram? Specifically also a shorter wavelength like 454nm or whatever lines your laser outputs that are more blue than green?[/quote:69d9bdd0e7]
It's unlikely to be lasing at more than "one" wavelength, but that wavelength may not have been 514. The laser is supposed to have a calibrated wavelength selctor, but I know the calibration's off, so what I thought was 514 may not have been. I did think of it, but had no way to check this. Unfortunately, there seems to be no way to backtrack from the output to the input. It would be great if, in colour holography, I could look at the output and say, "This, this and this wavelength went into this hologram in this, this and this ratio". But there seems to be no way of doing this. You have data on what went in, but not on what went out. If you see a full color hologram, you have no clue on what the input was, just the output. I have a few ideas along this direction, though. As I said earlier, I think we can learn a lot from the color coordinates that computer graphics people use all the time, instead of sticking to RGB. HSB, for instance.

DJ Mathson · Post by **DJ Mathson** » Wed Nov 10, 2004 2:43 am

Dinesh wrote:
D J Mathson wrote:You also have the Ultimate plates from Yves Gentet.
I couldn't see any sensitivity vs wavelength figures on their site. Has anyone done color with Ultimate. I I have an Ultimate hologram by Kris Meerlo , but its monocolored. Is Ultimate now producing film?

During the color holography course that I went to this summer we used Ultimate plates, the 08, if I remember it right. We also used the Slavich plates that needed hardening before developing. We used 442, 532 and 633 or 650 nm. In my opinion the Ultimate plates looked good. The Slavich plates had a somewhat greyish haze over the image. But I have a very limited experience of both these plates so I can not make any final judgement. Nevertheless the Ultimate plates seemed very suitable for real color holography.