Blue frenzy hits the holographer too

This is a forum to share experiences and ideas about holography.
wler

Blue frenzy hits the holographer too

Post by wler »

There has been for the last 10 days or so an incredible frenzy over the 1W 445nm Nichia diodes that can be harvested for like $30-50 from a Casio A130/140 projector; see the turmoil at the various light show and ballon popper forums. Well the holographer, being not particularly interested in wielding 1W laser pointers in public, is more interested in the mode stucture of these little beasties. So I had to get a few of those, and today, within the hour of receiving it, I set it up and checked the mode structure with my CCD spectrum analyzer. And voila - without any systematic search, I found that the diode runs single longitudinal mode up to 55mW (with Lens-27 at 221mA and 15.4C) ! This is truly exciting, not the least because the diodes are transverse multimode and apparently have many emitters. Here is a quick sample overview:

Image

From top to bottom the current was 221mA, 225mA, 300mA, and 400mA. I didn't turn the diode up to more than 500mA where it was yielding 430mW (with non-optimal Lens-27), because single mode cannot be expected at high powers anyway. Note the beautiful single mode at 221mA!

Most likely this can be optimized and I am about starting my computerized machinery for systematically finding sweet spots. Results should appear over time here. I tested also an ECDL setup but so far the power wasn't significantly higher, but this can probably be improved as well. There seems much work ahead, from long term stability to beam shaping (as such the beam won't go well through a spatial filter), but things appear much more promising as expected! Stay tuned.
Joe Farina

Blue frenzy hits the holographer too

Post by Joe Farina »

Wow! Please keep us posted. 445nm would be ideal for color holography.
DJ Mathson

Blue frenzy hits the holographer too

Post by DJ Mathson »

Yeah! I was looking forward to hear your results. I had the idea that it might be possible to shield off most of the emitters but it seems this isn´t necessary. Great news. I assume that more emitters kick in when you turn up the current.
Tom B.

Blue frenzy hits the holographer too

Post by Tom B. »

Truly exciting indeed. My compliments to wler for his contributions.
Colin Kaminski

Blue frenzy hits the holographer too

Post by Colin Kaminski »

This is indeed big news! Can you post a picture of the illumination pattern?

I am eagerly awaiting holograms!
DJ Mathson

Blue frenzy hits the holographer too

Post by DJ Mathson »

I hope the diodes are consistent, or rather that you got a bad diode... :)
Joe Farina

Blue frenzy hits the holographer too

Post by Joe Farina »

Since the bare diode is doing so well at 55mW (221mA) it would be interesting to try a simple, short-exposure hologram with it. 445nm would be absolutely ideal for DCG, and color holography as well.

The ECDL idea is also very exciting. It looks like Switzerland has become the leader in ECDL research for holography, with both wler and a_k making superb progress!
wler

Blue frenzy hits the holographer too

Post by wler »

Colin Kaminski wrote:This is indeed big news! Can you post a picture of the illumination pattern?

I am eagerly awaiting holograms!
The far-field pattern is indeed quite unpleasant and needs to be corrected at least in order to fit a decent fraction of the beam through a spatial filter. There are pictures of it all over, for example in
http://www.photonlexicon.com/forums/sho ... 312&page=1
and
http://www.laserfreak.net/forum/viewtop ... 2&start=75
I was looking into custom-made anamorphic prisms for this purpose, pondering about a group buy.

As for holograms, I am lacking right now film and space (my table is used for measurements). But indeed the ultimate verdict are test holograms! However so far things look preet good, I was finding a sweet spot at 64mW now, but it is quite narrow and it is unclear whether it would be stable enough. ECDL on der other hand went worse than expected, this needs a lot of further investigation. I wasn't yet even done with red ECDLs and now all this got interrupted by the "blue frenzy" ;-)
Colin Kaminski

Blue frenzy hits the holographer too

Post by Colin Kaminski »

The farfield pattern is indeed bad. It should be posible to get it into a spatial filter with a 6 to 1 compression. A couple of cylindrical lenses would give us a rough idea as to what could be done.

12.5mm Dia X 12.5mm FL Cylinder Lens MgF2 Coating NT48-352 $44.00
12.5mm Dia X 75mm FL Cylinder Lens MgF2 Coating NT48-355 $42.00

From Edmund would be a quick start but I am sure there are better prices around.

Where can one find these projectors? I am only finding new ones.
DJ Mathson

Blue frenzy hits the holographer too

Post by DJ Mathson »

Colin Kaminski wrote:Where can one find these projectors? I am only finding new ones.
Since this is a new product, there are only new projectors. What people do is they buy a unit and harvest the diodes. There are 24 blue diodes in each projector. At $800 they are $33 each. They are doing group buys at several places.
Locked