Lasers
HeNe | CO₂ | Argon Ion | Excimer

In our advanced optics lab at the college we have a dual-tube CO₂ laser.

It was my job to align the optics on this very large laser, there are two parallel tubes (folded), and about 3m of total gain medium. There are 4 mirrors (two of which are fixed at 45 degree angles), the remaining two were the output coupler and the high reflector.

To line up the mirrors, a HeNe laser was directed through the output coupler and through the laser with the shutter closed. The beam was lined up such that it passed through both tubes once and stopped when it hit the shutter. Once this was achieved the shutter was opened and the reflected beam was lined up. It was important to line up the beam going in the reverse direction as well, since this proves that the light will oscillate inside the laser cavity.

Copyright (c) 2003 Mark Csele
To be published in Fundamentals of Light and Lasers, Wiley, 2004
View of the laser operating, the second tube cannot be seen in this view, click the image to see an enlarged version

Above are a couple of images of the laser operating at about 20 W in CW mode.
The first image is of the laser burning into wood, and the second is of the laser striking the protective firebrick which is in the beams path for safety reasons

The laser is currently outputting 20 W of power in CW mode, and is being powered by a single 20kV neon sign transformer. Shortly (as of June 2003), the laser will be powered by two 20kV neon sign transformers (possibly floating) to hopefully produce upwards of 120W of CW infrared laser light.