ML501P73-2, a capless 638nm 5.6mm 500mW Red Laser Diode - Test results.

[andyf97]

Some Good news!!

Tested with no lenses to see the raw output and:

The emitter does in fact appear to be the same as the 300mW.

The divergence is larger but not by much, I did manage to get a similar beam as the 300mW using my test lenses.

So likely a shorter FL lens will be perfect just to take into account the larger divergence of the 500mW diode.

At one meter I have like a 5mm x 0.Xmm line + some considerable length wings. Pretty much the same as the 300mW.

Need a bit more time to get some shots and am also going to test a few other shorter FL lenses.

Don't get too excited yet tho, am still testing and hope to get a few photos soon.

Andy

[Fenechlaser]

i would agree that gas filled or liquid filled might be a bit much

Is arctic silver conductive? Would just placing a dab on the sides and placing the diode in a porperly made tight fit holder for better thermal conduction (someone mentioned this in some post) work better and allow more overdriving?

[planters]

Andy,
Thanks for the good news. What lens did you use for that first test that produced the 5mm wide stripe?

kiyoukan,
The problem with the bond wire heat is that to melt off they are running at hundreds of degrees while I guarantee that the emitter is running only a few degrees above the heat sink (based on wavelength shift). Lowering the heat sink temperature a few degrees will barely impact the wire temp and the maximum safe current will rise maybe 1-2%. I was not really serious about flowing deionized water. Although it might work it would be an incredible hassle. I am serious about lowering resistance, however. If a glob of solder or a conductive strip could be added the result could be interesting. Otherwise, I agree with Andy. Just limit the 73 series to a reasonable max.

[andyf97]

Ok, so I spent a few hours now trying different corrective options and looking more and more at the diode.

Bottom line is NOPE, the 500mW is indeed worse to correct that the 300mW.

I will try again when the corrective stuff comes from the kiyoukan BG

[planters]

I assume the corrective optics will improve both diodes by the same ratio. 6:1 in both cases. What did you find? How much of a difference between the two diodes. With a given lens what kind of numbers did you see?

[Stoney3K]

Andy,
Thanks for the good news. What lens did you use for that first test that produced the 5mm wide stripe?

kiyoukan,
The problem with the bond wire heat is that to melt off they are running at hundreds of degrees while I guarantee that the emitter is running only a few degrees above the heat sink (based on wavelength shift). Lowering the heat sink temperature a few degrees will barely impact the wire temp and the maximum safe current will rise maybe 1-2%. I was not really serious about flowing deionized water. Although it might work it would be an incredible hassle. I am serious about lowering resistance, however. If a glob of solder or a conductive strip could be added the result could be interesting. Otherwise, I agree with Andy. Just limit the 73 series to a reasonable max.

I think there's a combination of some factors involved here that causes the bond wires to blow at the contact point.

The contact point itself doesn't need to be heated to hundreds of degrees for it to melt, because the wires also carry about an Amp of current while they're micrometers apart -- this would cause them to generate a considerable magnetic field on such a small surface.

If those bond wires are parallel, they'll be pulling each other together due to their magnetic fields, causing a tug and shear force on the bond wire attachment. That only needs to heat up just to the point where the connection is weakened, and the force combined with the weaker bond material will pull everything up to breaking point.

Running the diode in a modulated way (as we do in projectors) may make the situation even worse, because it also creates a fatigue stress on the attachment point, because the bond wires are effectively vibrating under their own magnetic forces.

[chad]

Believe me, bond wires can go in other places as well.

chad

[swamidog]

hey chad, why does your diode have a spark gap?

Believe me, bond wires can go in other places as well.

chad

[CDBEAM]

ANYONE else......do any optical experiments with the P73-2 LD yet ??? Is this one a Photon Phog Horn ?????? Anyone try 12X Cylinderical PCV + PCX ?????

BEAM

[LaNeK779]

i think the only good news we will get with this one is when someone gets it GRINed...