Heatsink positioning?

[dnar]

Hi guys, I just received a 200mW 532nm DPSS module from DX, it is 11.9mm with what appears to be an M10 thread. DealExtreme: $46.81 200mW 532nm Green Laser Module (3V 11.9mm)

I have a 10mm thick right angle ali bracket as a heatsink for this module, but I am wondering which end of the module requires the most cooling, the lens end (to cool the crystal) of the diode end?

So, should I tap an M10 thread for mounting, or 11.9mm and position the module so that the diode end is in contact with the large chunk of heatsink?

Someone here mentioned that the crystal used in these modules is not large and can burn out so hence my thought of screwing the module in to the heatsink providing for a cooler crystal.

Thanks in advance!

 

[Prototype]

I think placing the heatsink nearest to the diode would be best, perhaps a bit ahead of it as the diode and crystals are close together. How thick is the bracket, if I may ask?

 

[goninanbl00d]

Preferably, the whole module should be heatsinked.

But in your case, the pump end is more important. The KTP prefers warmer temperatures (80C) for maximum efficiency. The pump end will also get warm extremely fast without a heatsink. The Nd:YVO4 is usually straight up against the pump diode, so you'd probably be able to heatsink both elements in one go.

Look at the back of the module- you should be able to see where the pump diode is located. Place the heatsink over the pump diode. (on my module it's about 5mm from the start of the brass casing going from the driver end)

Also- I doubt it's actually 200mW. Going by DealExtreme's standards, it'd probably be in the 100s somewhere.

P.S. Looks like you were lucky.

- Attention Australian Customers: due to new regulations enforced by the Australian Customs, orders of >1mW lasers units shipped to the Australia are no longer accepted. Orders that were previously accepted and unshipped will be cancelled and refunded to customers. This affects Australian orders only.

 

[dnar]

I think placing the heatsink nearest to the diode would be best, perhaps a bit ahead of it as the diode and crystals are close together. How thick is the bracket, if I may ask?

Ok, thanks.

The bracket is 10mm thick as per my first post.

Cheers.

+1 for the tip.

 

[goninanbl00d]

That should be more than enough to cover the pump diode and the YVO4.

 

[dnar]

Preferably, the whole module should be heatsinked.

But in your case, the pump end is more important. The KTP prefers warmer temperatures (80C) for maximum efficiency. The pump end will also get warm extremely fast without a heatsink. The Nd:YVO4 is usually straight up against the pump diode, so you'd probably be able to heatsink both elements in one go.

Also- I doubt it's actually 200mW. Going by DealExtreme's standards, it'd probably be in the 100s somewhere.

P.S. Looks like you were lucky.

Yes, very lucky!

One thing I have observed with a 50mW green (inbuilt driver) in the same heatsink, is that once the night time temps get below 20c, the current drain drops (300mA at 25c, down to 230mA at 15c) which I am sure is due to the optical feedback. Without a LPM it is hard to determine if the output power changes, I can't detect any change.

What is the optimal case temp of a DPSS? I have a Peltier and driver I was planning to add to the 200mW, but from what I have measured with a 50mW is that I might need to regulate the temp by heating rather than cooling. This chunk of heatsink is large, 10mm thick L: bracket approx 4" x 2".

 

[Prototype]

Oh *facepalm*, it's 5:45 am, my bad. That should be plenty, as gonaninbl00d said.

 

[dnar]

Oh *facepalm*, it's 5:45 am, my bad. That should be plenty, as gonaninbl00d said.

Thanks man! Go to bed! :thanks:

 

[goninanbl00d]

I used to be concerned about heatsinking.

Now I'm not.

I let my module warm up in my hand, otherwise it mode-hops between TEM00, pseudo TEM00 (with a small lobe to one side) and TEM10.

It'd be more important to keep the temperature consistant. Add the Peltier and a thermistor and try to keep the temperature at 25C. That'd mean cooling it in summer, and heating it in winter.

 

[dnar]

I used to be concerned about heatsinking.

Now I'm not.

I let my module warm up in my hand, otherwise it mode-hops between TEM00, pseudo TEM00 (with a small lobe to one side) and TEM10.

It'd be more important to keep the temperature consistant. Add the Peltier and a thermistor and try to keep the temperature at 25C. That'd mean cooling it in summer, and heating it in winter.

Ok, so I might setup a H bridge driver that provides cooling and heating as required.

Thanks! +1 rep.

 

[goninanbl00d]

No problem, mate.

Always glad to help when I can.