DCG Wavelength Sensitivity

baja · Post by **baja** » Sun Dec 05, 2010 4:29 pm

Hi All,

I'm thinking about getting a laser for some home DCG holography.
The 315m looks like a good choice but I think the sensitivity is low
at 532nm, so maybe I should get a shorter wavelength (like 488 or
479), but they seem pretty expensive. I might go that route if they
have a big advantage for DCG. I spent hours online but can't find
any sensitivity curves for DCG, so I'd like to hear from members
who can vouch for the relative sensitivity.

An obvious question is how many mJ/cm^2 is required to record.
That will give me an idea of exposure times.

Thanks in advance!

Joe Farina · Post by **Joe Farina** » Sun Dec 05, 2010 4:46 pm

Hello Baja,

Straight DCG is most sensitive to blue or violet light, and it's easiest to make DCG with wavelengths around 442 to 488nm. However, that's also the most expensive light, because it needs to have enough coherence length. Blue, highly coherent light is quite expensive. Although I haven't used 532nm for DCG, it can be done quite easily, though as you mention, the sensivity is less, so you have to use a higher percentage of dichromate. To get a feel for things, I would go to the Holography Forum archive at the bottom of the main page of this forum, and put some search terms in the search field like DCG, 532nm, 315M, dichromate, etc. There will be a lot of things to look at, to provide guidance. The 315 is a very good laser. I would suggest the 100mW variety if you're working with DCG, the extra power will come in handy. There might be some good deals out there for blue lasers, just be certain they have enough coherence, and expect to pay more than $1,500, which is about what the 315M goes for.

Johnfp · Post by **Johnfp** » Mon Dec 06, 2010 10:19 am

I still use Slavich's site as a baseline starting point.

http://www.slavich.com

Then go to Emulsions for Holography on left, then PFG-04.

baja · Post by **baja** » Tue Dec 07, 2010 2:15 pm

Awesome! Thats an excellent site and I'm sure I will be a customer of theirs soon. It looks like 479nm would be about 1/5 the exposure of 532, unless I used some presensitizing tricks I've read about, in which case 532 looks to be very fast. Thanks for the tip.

Dinesh · Post by **Dinesh** » Tue Dec 07, 2010 3:19 pm

Here are dcg sensitivities:

142laser · Post by **142laser** » Thu Jan 27, 2011 1:19 pm

Hi,
Wow I did not realize how much better blue is than green for this media. I still have the best of my 479 nm SLM Coherent Sapphire lasers for sale with only 165 hours use. It is 200+ mW capable and I am asking $6K. I also have a Coherent Sapphire HP 488-200 coming in soon. I will test it for SLM; it has 420 hours on it and I am thinking $7,500 with the Coherent CDRH lab supply and software for computer control of the laser. Phil 142laser (813) 974-2378