Effects of High Beam Intensity

Written by Tom Nugent on Friday, July 6th, 2007

After we received our laser back in May, we started testing it. First came a set of bench-top tests. We used a foamed carbon block as our beam dump, and here’s what it looked like during the second test of one session:

After the tests, you could see some permanent marks on the beam dump:

Those marks on the foamed carbon block are from the carbon oxidizing, which doesn’t happen until well over 1,000 degrees C. The calculated power density from the test is somewhere over 220 times normal solar intensity (outside Earth’s atmosphere), i.e., on the order of 330 kW/m^2. The intensity is this high not because the laser put out so much power (it was actually low for what the laser can put out), but because the beam stop was close to the laser and therefore the laser energy was concentrated into a very small area.

These photos highlight yet another reason why everyone must be extremely careful when working with class IV lasers. Even if the total power used in one test is relatively low, it comes out of a small area and hence is very intense. Safety is the highest consideration when working with lasers, and we take the ANSI Z136.1 safety rules very seriously.

Oh, and as a result of our tests, we now know the laser stack output at low power, and overall we’re happy with the performance of the laser stack. We’re testing regularly, and will have more to report on in the future.