annoying fringes in hologram

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blue_electric_71

annoying fringes in hologram

Post by blue_electric_71 » Fri Jun 11, 2010 5:35 pm

Hi, i've been doing some tests and every one of them turned out like this one:

http://vimeo.com/12493171

I use integraf's jd4 kit. exposure 30 seconds, development 2 minutes. They turn out quit bright though.
Could this mean slight motion/vibration, or a mode hopping problem?. I read Max's post on a similar problem:

http://www.holographyforum.org/phpBB2/v ... ing#p56462

I just use a simple overhead single beam setup. The video show some clay scarabs and pretty little shiny things..I put them in a black painted metal cup about 1 inch deep. But as you can see the black fringes seem to emanate from each object's center/pivot point..

The is also quite some dust on the concrete floor in the basement where I shoot. Could dust particles be responsible for this effect?

Thanx in advance :pray:

Gilbert

rzeheb

annoying fringes in hologram

Post by rzeheb » Fri Jun 11, 2010 6:00 pm

Hi Gilbert,

Looks like a mode-hopping laser to me. What laser are you using and at what power level? How long are you letting the laser warm up before shooting? Without looking back at your other threads I would assume that you are using a low-power diode? If so, it would be pretty inexpensive to try a different diode, maybe one from Integraf. Even so, it looks like you're making great progress. Keep up the good work! Best, Ron

dave battin

annoying fringes in hologram

Post by dave battin » Fri Jun 11, 2010 6:08 pm

mode hopping, bread slicing, diode laser!

blue_electric_71

annoying fringes in hologram

Post by blue_electric_71 » Fri Jun 11, 2010 6:47 pm

Thanks for the quick reply, I use integraf's 5 mw laser diode...rather odd they would sell you a laser diode that does mode hopping...or could that be different on every single one of them..

I'm not quite ready yet to pay $1200 dollar or so, on a more high-end laser. What would be a good alternative for the one I got from integraf?

Well, at least I now know what the problem is..and I'm not planning on making just coins on the 12 plates I got left.

I have been doing some reading on DCG...but first I need to get the hang of making holograms with commercially available plates and chemicals
So before I decide whether to invest in a more expensive red or green laser I need a cheap(ish) red laser diode that is stable..

Thanks again
Gilbert

Tom B.

annoying fringes in hologram

Post by Tom B. » Sat Jun 12, 2010 3:29 am

More details on your setup, environment, exposure time, and how long you are allowing things to settle before exposing would help. I thought at first classic sliced bread from either diode multimode or plate movement, but then noticed that some of the objects are perfectly free of fringes. I suspect that some of the shells are moving somehow. Maybe try some blu-tack or something to keep them from moving? - the shell should contact the support, and should not be resting on blu-tack - just use little balls of blu-tack around the contact point to keep it stable. Small amounts of room vibration can make unstably supported things like shells rock and roll quite a bit.

You are wise to plan on getting your feet wet with commercial plates and gaining some confidence before diving into DCG and expensive lasers. I think most low-power red diodes are OK, it's just that so much else can go wrong such as vibration etc.

Colin Kaminski

annoying fringes in hologram

Post by Colin Kaminski » Sat Jun 12, 2010 4:59 am

Just in case warm up your laser for about 20 minutes. I have not had an Integraf 5mw mode hop unless I tried to change its temperature during exposure.

blue_electric_71

annoying fringes in hologram

Post by blue_electric_71 » Sat Jun 12, 2010 2:05 pm

- I let the laser warm up for about 30 minutes, while I set up the scene . I also use a 3 volt mains power supply instead of batteries.
-after that I let it settle for another 30 minutes
-Exposure is 40 seconds (i really need an electronic shutter there...)
- Rinse 20 sec
- Develop 2 minutes
- Rinse 3 minutes
- Bleaching for about a minute + 20 seconds
- Rinse 3 minutes
- Photo flow bath for 1 minute

I will try the adhesive putty you suggested....I guess double sided tape would'nt work ?

When it comes to drying, is it better to let it dry naturally than using a blow dryer?

Anyway, I'll post some new attempts later on...and Tom, I really love your holograms on your site...space kitty rules! How do you get them so bright and sharp..even with the doll's hair it's amazing....I would like to reach that level of quality some day.. :clap:

cheers,
Gilbert

jnhong

annoying fringes in hologram

Post by jnhong » Sat Jun 12, 2010 2:22 pm

IF your ambient temperature is fairly stable, Integraf's laser diodes don't need more than 10 minutes of warm up time. They're typically very stable after 5 minutes. Laser diodes are very sensitive to backreflections, however. Shiny objects may reflect back enough power to mess up the laser output. Can you change the overhead angle and see if that eases the problem?

Stability of objects and setup is ALWAYS the biggest concern. If your objects are not rigidly affixed to their places, it's the first thing that messes up the hologram exposure. Your holograms are bright and clear enough to assume that the setups are mostly rigid and stable. I would recommend moving to battery power, but your success with these holograms indicates the laser diode is working to 90% of expectation. Mains power supplies generate a lot of heat, not a good thing in proximity to a holographic recording setup.

I had a few earlier posts on my experience with laser diodes. If you read those you might recognize some issues you are encountering.

Joe

dave battin

annoying fringes in hologram

Post by dave battin » Sat Jun 12, 2010 2:24 pm

go back to batteries and see if the fringes go away, the power supply needs to be good and stable !.................. this could be your problem

BobH

annoying fringes in hologram

Post by BobH » Sat Jun 12, 2010 2:42 pm

Very cool hologram! The fringes are so symmetrical on the objects they cover. :)

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