styropyro

air force solar laser

Added 2022-11-20 01:45:50 +0000 UTC

I recently bought some equipment in an auction from a small photonics company in St. Louis that was closing doors. The company owners were three physicists in their late 80s that were super smart and a lot of fun to talk with. I bought a bunch of useful stuff there, but the most interesting item I won was definitely this solar pumped laser that was built for the US Air Force in 1976.

The work that went into designing this was crazy and I don't even want to know how much it cost to develop. Apparently there was a push to make a laser that was directly powered by sunlight that could be used in optical communication when mounted on a satellite, along with a complementary solar telescope to drive it. There were a few prototypes built before this one, and the one here was built to the specs to be ready for operation in space.

Using the sun to directly energize a laser crystal was not a new idea, and in fact some of the first CW lasers ever built used solar pumping. However, in 1976, a laser system like this (a self modelocked, frequency doubled Nd/Cr:YAG laser) would typically be arc lamp pumped, which is power hungry and inefficient and simply unfeasible to mount on a satellite. Thus, the idea of using sunlight to directly energize the laser crystal was appealing at the time. Not long after, laser diode pumping would prove to be a much more efficient and easier to control method, but this project was still very cool.

It's funny because a solar pumped laser has been on my list of projects to try for quite some time, but after seeing how this laser was designed, it has made me second guess how I would go about it.

You can read the whole 100+ page report on this very laser here!

https://apps.dtic.mil/sti/pdfs/ADB015176.pdf