Firsts Casio diode hologram @ 445nm

This is a place to post pictures of your latest work.
dave battin

Firsts Casio diode hologram @ 445nm

Post by dave battin » Mon Aug 09, 2010 1:34 pm

Joe Farina wrote: By the way, were you using any kind of feedback to the diode?
Not that i am aware of ! I will start working on better optical set up now, so when i do the teardown ill test to see if there's any feedback from the back reflections............. Joe did you get your diode going yet .

Joe Farina

Firsts Casio diode hologram @ 445nm

Post by Joe Farina » Mon Aug 09, 2010 1:50 pm

dave battin wrote:Joe did you get your diode going yet .
I had to return the first, but another one is on the way from Thieu. I've also ordered an AC/DC adapter, and have a driver that Ahmet provided. I will need to make a heatsink from aluminum. I checked Wolfgang's pages this morning, and he said he was getting 80 to 120mW single-mode with simple feedback (no grating). Once the diode comes in, and I get the other things together, I'm planning to try shaping the beam with two cylinder lenses, to see what it looks like. Thieu has an interesting idea of placing a micro-lens close to the emitter (by opening the can of the diode). In that case, there would be practically no expansion before it hits the collimating lens, which might go a long way to solving the beam-shaping problem. It does sound like a ticklish job, though.

Thieu

Firsts Casio diode hologram @ 445nm

Post by Thieu » Mon Aug 09, 2010 8:33 pm

The beam shape is not as bad as it seems. At the low currents where SM operation seems to be easily achieved, the beam is pretty much like a TEM00 beam, just very elongated, but still gaussian in both directions. It's only at the higher powers that the outer regions of the stripe start to emit and the beam gets bad. See my post here: http://www.holographyforum.org/phpBB2/v ... =30#p57701
If you can collimate the beam with two cyclindrical lenses like explained here: http://www.newport.com/store/genContent ... 70345/1033 , you will have no problem sending it through a spatial filter.

Joe Farina

Firsts Casio diode hologram @ 445nm

Post by Joe Farina » Mon Aug 09, 2010 9:04 pm

Thanks for the link to the cylindrical lens tutorial, Thieu. I made a note of it.

When I bought a Melles Griot 457nm laser, a nice mechanical component came with it. This is to hold and adjust two cylindrical lenses, to correct the elongated beam. After some trial and error, I got it to work. It has a rather large cylinder lens in one mount, and a much smaller one in the other. Apparently whoever had the laser before me chose to use this method to correct the beam profile. However, the 445nm diode is quite a bit different from the Melles Griot laser. I will have to see what happens.
Attachments
P8090018.JPG
P8090018.JPG (39.01 KiB) Viewed 4133 times
P8090019.JPG
P8090019.JPG (39.34 KiB) Viewed 4133 times
P8090020.JPG
P8090020.JPG (41.94 KiB) Viewed 4133 times

Locked