520nm diodes - Beam shape? Bias current? Cooling?

[hakzaw1]

15
0000000000 subbing

good info
thanks to all!!

[andy_con]

https://docs.google.com/file/d/0B_6-...bHc/edit?pli=1

operating temp of up to 50 degrees, does the base plate in your projector get to 50 degrees?

I suspect it gets no where near 50 degrees, so don't bother tec'ing it. just a good diode holder and heat sinking via the base plate, with a tec you will have twice if not more heat to remove

[planters]

Andy is right. These are GaN diodes (and very similar to the 445nm diodes) I suspect that like the blues these will gain a little from aggressive cooling, but not much. To get a 10% increase in the blue diodes you have to isolate the diode and its mount from the atmosphere and bring the temperature to < 0 degrees. It's not worth the effort. Just mount the diode holder to the base plate with tight clamping and thermal grease.

Cylinders work a little better than prisms and you should plan to use them otherwise you will end up with a thin rectangular beam at the scanner and a wide rectangular beam in the far field. A longer FL collimator would decrease this problem in the one axis but then the other axis will produce the same problem in reverse. With a long enough FL the lower divergence axis can go negative. This will be a very tight beam, but also a very asymmetrical one.

[greenalien]

OK, so if I just mount the diode holder plus lens in a block of aluminium, (drilled to fit, slotted on one side with a clamping bolt to hold the diode housing firmly in place), the block then bolted to the base plate, then I don't need a TEC cooler at all? And I should get a G2 long focus lens for the tightest beam, but then clean up the asymmetry with a pair of cylindrical lenses?

[andy_con]

Get a brass diode holder from dave

[LaNeK779]

Get a brass diode holder from dave

or even better, get one of the copper ones he has available for the 9mm diodes

[andy_con]

Perfect .

[mccarrot]

I personally would no longer bother with a P3 driver; Alex's drivers from LaserTack are better:
http://www.lasertack.com/en/laser-diode-drivers

Alex's drivers are indeed nice drivers. good qulaity good footprint, good manual, and easy to adjust.
the only problem is I had is the wires included with the drive are .22mm^2. with a 2A for the diode and 1A for the TEC= 3A trought the 0.22mm^2 is not a good option. when the tecs kicks in you see the laserdiode dimming due to the voltage drop over the wire.
Its easy to solve by soldering 1mm^2 wire direct to the PCB for the power.

Maurice.

[danielbriggs]

Good point Maurice,
I didn't experience this, as I used my own hook up wire.

Dan

[planters]

I like LaserTack's prisms. So I don't doubt his drivers are good. Dave's drivers are good as well. will handle 2A and are dual channel. So, if you choose to double the 520 diode in the future you will have the additional channel already. The TEC control should not be needed and you probably want Dave's copper mounts in any case.