New to the forum and lasers.

Kenom · Post by **Kenom** » Tue Jul 20, 2010 7:32 am

Hello everyone. I'm a big laser aficionado and was recently shown this forum as a source of some wonderful information on holography. I actually got to know one of the professors at my university who was in charge of the holography courses and was absolutely fascinated by the prospect of doing my own holograms.

I have read through the forum a bit and will not bore you with a bunch of silly questions about what is or is not needed in order to do holograms. I'm capable of searching and will do so before I ask a question that may have been already posted.

To date, I have quite a few lasers ranging from 1mw HeNe (spectra physics) to a 1W 445nm multimode laser. I will list the other lasers at the end of this posting

I manufacture laser pointer hosts. I know that a lot of folks sneer at the laser pointers as being ridiculous and dangerous and I totally agree. Safety first! I am a member of the dreaded LPF *(laserpointerforums.com) for over 3 years and have developed a Laser power meter called the Kenometer. (I saw someone posted a link to the meter in the for sale section as a potential source for a thermopile based laser power meter. I do hand make them, so build quality isn't the greatest, but given that each one is assembled by myself alone, I think they don't look bad at all.

My main interest in joining this forum is to make a hologram using a 405nm laser. I don't know for sure, but was told by the professor that as long as the diode puts out a single mode, the laser can be used for holography. The diode is single mode and can put out anywhere from 1-60mw depending. Hope to meet and develop some friendships here. I already recognize one person Bobh and am sure I will recognize more.

list of lasers to date.
Kryton Prototype 660nm laser pointer (280mw)
5 assorted modules with 650nm laser diodes at 1-5mw.
3 Assorted modules with 405nm laser diodes at 1-200mw
Kryton groove laser pointer 445nm multimode 1.02W
Lasertel fiber coupled 800nm diode 40W (plan on making a fiber coupled engraver eventually)

a_k · Post by **a_k** » Tue Jul 20, 2010 10:43 am

Hello Kenom

Welcome to the forum. I do know you from LPF and it's possible that i participated in one of your GBs there.

To the subject: The PHR diodes and other 405nm diodes i know of are all strongly multimode. About 2 years ago i got interested in 405nm LDs and made tests recording holograms with them. Here is the thread i started: http://www.holographyforum.org/phpBB2/v ... f=2&t=6493

The very first LD was usable but all others tested were strongly longitudinal multimode. Others have tested the diodes as well and came to the same conclusion, the bare diodes have very short coherence lengths, fractions of a mm - a couple mm usually.

Wler had success with the 405nm LDs but he was using them in an ECDL configuration and got an output of about 15mW.
http://redlum.xohp.pagesperso-orange.fr/laser/ECDL.html
http://redlum.xohp.pagesperso-orange.fr ... ml#blueray

This might sound like little but as the recordings materials (DCG) are very sensitive to 405nm 15mW is a lot to work with. With laser diodes it is essential to have a very accurate temperature control, 0.01°C at least, a noise free diode driver, to select carefully which LD to use and to set the LD in a stable operation region. For ECDL in addition a grating is needed, which sends some of the LDs output beam back to the LD, selectivly frequency filtered.

In my experience using the 405nm LDs for holography is not a trivial matter. If you happen to know of LDs with this wavelength which run reliably longitudinal single mode, i would be very much interested to learn about the and i'm sure many others would be interested too.

Good luck.
Ahmet

Jem · Post by **Jem** » Tue Jul 20, 2010 12:06 pm

Hi Kenom

And welcome to the holography forum. I've seen you over on Photonlexicon and it's nice to see another holography 'convert' make it over here

Cheers

Jem

BobH · Post by **BobH** » Tue Jul 20, 2010 2:14 pm

Yes, welcome to Holotown! You won't be "baited" by drama queens or banned from here for participating in discussions like the children at LPF do. :wall: Here, you'll find people who actually USE lasers for something constructive while appreciating the wonderful beams they produce.

I've recently made a hologram with a 405nm laser pointer. Typical of the dishonest bastards who produce laser pointers, this one was labeled for 5mW but puts out 35mW. Anyway, I used it in a contact copy arrangement with a "master" hologram having 50% diffraction efficiency. Coherence length requirements for this geometry is minimal. Making a pictorial hologram master tuned for 405nm would be tricky, but possible, using something like 532nm where coherence length and power are plentiful.

Jeffrey Weil · Post by **Jeffrey Weil** » Tue Jul 20, 2010 3:17 pm

Hello Kenom,

I posted that comment about your meters. I hope that didn't offend you. Ok, back to your post.

When I started making holograms in the 80's I listened to what Bob H and Ed W had to say on what to do and they never steered me wrong. Now 25 years later I'm still in the industry full time. This was back in the day when you had to go to a symposium to meet up with these guys. Now there right here on this board. Take advantage of what they have to say.

Ok, back to the meter. While your meter wasn't the best choice for me it's a fine meter and has the coolest features of all of them. The best display, peak readings and data logging. If you need that stuff it's the right choice. I just needed something simple.

Here's the Kenometer page http://www.kenometer.org/

Jeff Weil
NorthBeach Holography Inc.

Kenom · Post by **Kenom** » Tue Jul 20, 2010 5:00 pm

thanks for the warm welcome guys. Bob, if your here, that speaks highly of the integrity of this forum and not the child like tendencies of LPF. I look forward to having intelligent conversations about lasers and it's uses. Not oooh look what I can burn! LOL. As to the other stuff you said about teh 405 hologram, I didn't understand, but I'm still fresh on holography and don't understand what is really required and how it's truly accomplished. Not to worry though, I'll learn

Jeffrey, your comment did not offend me. I will be the first to admit they are not professionally assembled. The fact that you mentioned it as a potential source for a power meter though, was a good thing. Apparently the build quality didn't throw you off completely.

Honestly, the meter wasn't built specifically for holography enthusiasts. It was designed for those that build higher powered lasers, which aren't needed for holograms, to see what their builds truly are putting out. So, I'm honored that you at least mentioned it. I'm not here however to "hock" my meters. If you want or need a meter, I'll sell ya one, but I really am here to learn about holography!

Time to read and learn!

Jeffrey Weil · Post by **Jeffrey Weil** » Wed Jul 21, 2010 1:18 pm

Hello Again,

I forgot to mention Jeffrey Murray. Those are the 3 that helped me the most when I was starting out.

Jeff Weil

Colin Kaminski · Post by **Colin Kaminski** » Thu Jul 22, 2010 12:53 am

BobH wrote:Yes, welcome to Holotown! You won't be "baited" by drama queens or banned from here for participating in discussions like the children at LPF do. :wall: Here, you'll find people who actually USE lasers for something constructive while appreciating the wonderful beams they produce.

Just as a side note...

Running a forum can be quite stressful even when everyone is conscientious, intelligent and considerate. For fora that draw a larger cross-section of people the administration issues must be quite difficult. I have not visited any laser fora but I can see how I would not like to administer them.

Cheers Kenom!

Kenom · Post by **Kenom** » Thu Jul 22, 2010 1:13 am

Bobh was banned from that other forum and I don't believe it was a right decision. Needless to say, we don't need to be bringing that drama here. I see his knowledge as a good thing and look forward to learning from him.

Colin Kaminski · Post by **Colin Kaminski** » Thu Jul 22, 2010 6:42 am

Bob is the greatest and I can't imagine this forum without him.