K40 Laser Power Meter - easy & cheap!

Upshot: You can't tell exactly how strong it is, but I guarantee you it's under 9000.
I'd like to hear if any of you try other coatings and find them to work as well. The key is to get one that'll absorb the infrared energy, but won't burn up immediately once it gets hot!
Here's a playlist for all my K40 laser stuff:
• K40 Laser Stuff
Donations help me make more cool shit:
paypal.me/swolebroshopworks

[@klave8511]

The absorption rate of water is very high (lots of data online because CO2 lasers are used for surgery) as long as you don’t boil it off at the surface, it may be a good reference absorber to calibrate your probe. The heat capacity of water is very high and I guess you should use a styrofoam cup so you don’t heat up the container. Unfortunately you can only measure a vertical beam because the water is a liquid.
You can use the min/max functions on you thermometer to do the test, clear them when you start and it uses the current temperature for the min. Read them after you’ve run the test and the maximum will be stored too. Now just subtract.
BTW, the wavelength is 10.6 micro meters, very far infrared.
Great video, love the soot idea. I see some people use a piece of heatsink, don’t think the black is necessarily better than just plain anodizing but they are anodized and aluminum oxide is a good absorber at this wavelength.

[@pietzeekoe]

Did you end up upgrading the mirrors and lens? A lot of the online guides and reviews on the K40 list upgrading the lens and mirror as a must. I wonder how much of a difference it makes.

[@swolebro]

Hahah, a homegamer finishing a project! That's a good one. I've continued using it in a mostly-stock configuration. Still cuts 1/4" oak well enough, albeit charred. The machine should get some more attention come August. The past six months I've been busy moving/downsizing, so the Ender and K40 are going to be focal points of my new workspace.
No welding in an apartment, unfortunately. At least that makes more times for electronics/prototyping/etc., and I've found a public makerspace that will help fill in the gaps when I need specialized stuff.

[@pietzeekoe]

@@swolebro I feel ya. It's hard making time for projects. I actually came across you channel when researching LinuxCNC for a plasma cutter, all I've had time for so far is installing LinuxCNC on a computer. The K40 seems like a good (relatively) quick way to get my feet wet with this whole CNC thing.
I guess your relocation means the plasma CNC is gonna get mothballed. I hope your relocation was due to positive reasons, downsizing a home workshop must suck.