Welcome to Laser Pointer Forums - discuss green laser pointers, blue laser pointers, and all types of lasers

Laser Pointer Store

Extending the duty cycle on a 1150 mw 445 nm laser via cooling methods

Oct 24, 2008
In truth most diodes can easily operate at temperatures we would consider "hot". I kinda baby my builds and turn them off when the get IMO "warm" to the touch. I figure if the outside of the host is warm than the diode is hot. In fact rarely ever have I read of a diode failing because it got too hot. Most of the time the output just diminishes by as much as 30%, but once they cool they're okay again.

Actually I'm more concerned about the driver. It's really annoying that Dr. Lava is out of the Flex Drives right now. The Boost drives work but they've only got about 90% efficiency at best. That may seem high but 10% of the 6w that the driver draws from the battery is actually quite a bit for those tiny components. Even if you do glue a small bit of aluminum to the switching chip, they're still more likely to fail before the diode. If that happens they may take the diode with it.

And BTW.. High thermal mass like that host you pointed out has an achilles heel as well. While lots of thermal mass makes it slow to heat.. It also makes it equally slow to cool off.
That's true. What you're referring to is a material's Specific Heat. Basically it's a measure of how much thermal energy a given volume of the material can contain. Liquid water actually has a high specific heat compared to most metals. That's why it's ideal for pumped cooling systems. If you've got a sq inch of water and a sq inch of aluminum, both at 100 degrees, the water contains more thermal energy.

Typically you'll want good heatsinks to have a low specific heat. That way it only has to absorb a little bit of energy before its gets "hot" so it can be radiated away into the air quickly. However, I'd argue that for our "heatdump" builds, you would want a heatsink with a high specific heat. That way it can absorb high amounts of thermal energy before it gets "hot" to the touch. It acts like a heat capacitor. Yes it will also take longer to cool, but for most practical cases that shouldn't be a problem. If it didn't have a high specific heat temperature would rise faster and saturate quicker.