What's with the Purple?

Occasionally people will ask us why our web site has an abundance of purple in it. The purple hue throughout our site is representative of the plasma discharge of CO2 lasers. The picture above is a snapshot taken of a healthy CO2 laser during operation. The discharge of the laser is one of the many aspects of the lasers operation that is helpful in diagnosing a malfunctioning machine. Impurities in the gas, gas leaks, power problems, and many other conditions can create varied colored discharge. In short we always like to see this color when we are working on your laser.

Q. Okay purple is good, but what's this about discharge?

A. Without going into stimulated emissions, population inversions, quantum mechanics, and thermodynamics, the discharge can be best understood by looking at how CO2 lasers work. CO2 lasers use carbon dioxide, nitrogen, and helium as a laser medium. We'll focus on the nitrogen and the carbon dioxide. Before the laser can fire, the resonator must be evacuated of all resident gasses and then it is filled with a specific mixture of gases. After the gases are introduced into the resonator, energy (DC or RF) is pumped into the laser medium. The nitrogen picks up this energy but because nitrogen is a homonuclear molecule (molecules comprised of only one element) it can't lose this energy as photons (light waves). The "high powered" nitrogen then collides with the CO2 molecules transferring their energy, but because CO2 is not a homonuclear molecule it is able to return to a normal vibrational state by releasing some energy as photons (light waves). The helium acts as a coolant for the process and it also assists in returning the CO2 to its normal state. This happens over and over again until the laser is powered up and ready to fire. The discharge of power from the high energy sources of the resonator and the nitrogen/carbon dioxide mix produces a faint purple glow.

Q. Was that your definition of a simple answer?

A. No, but in that instance it is about the simplest way to put it. The CO2 laser was invented in 1964 by Kumar Patel of Bell Labs and it remains still one of the most useful lasers today. Kumar Patel built upon the work of physicists all the way back to Albert Einstein and his work on the photoelectric effect, so from the start lasers were already complicated beasts. Interestingly enough lasers are one of the few real world examples of quantum mechanics in action.

Q. Okay that's great, but can you fix my machine now?

A. We'd love to. Please contact us to schedule a service visit.

AvidTek, Inc. 2016