What Elements Are Used in Blue-Green Lasers?
- Lasers create a special kind of light.fond zulux laser image by Strikker from Fotolia.com
Lasers work by bouncing light from an external source back and forth between two mirrors inside a gas or solid medium. To be effective, the medium must be pure so that all the atoms inside the medium vibrate at the same wavelength. The medium must resonate like the pipe in an organ to produce a strong beam. Blue-green laser light comes from argon gas in an ionized form and is used in biomedical instruments. Creating blue-green laser light from argon gas requires specialized equipment.
The Laser Tube
- A tube with a ceramic liner contains the argon gas. The outside energy source loads the gas with energy, heating it to a temperature equal to the surface of the sun and removing one or two electrons from the argon atoms. These depleted atoms are called ions. The hollow core is contained within tungsten disks mounted inside copper disks to aid in heat dispersal. The earliest tubes were made with simple quartz.
The Power Source
- An external power source starts the process. It can be another light source or electricity. Some small argon gas lasers run on 110-volt house current.
The Mirrors on Each End
- The mirrors at each end of the tube are vital to the laser. The argon gas atoms respond, not only to the light from the external source, but to light careening back and forth between the mirrors. The back mirror is completely opaque and reflects all of the light striking it. The front mirror is partially obscured. The laser light bounces back and forth until it has enough energy to burst through the front mirror.
The Magnetic Field
- The tube is contained within a magnetic field that pushes the plasma away from the walls of the tube and the tungsten disks. Failure of the magnetic field will allow the heated gas to damage the walls of the tube. Small argon gas lasers are air-cooled. Larger lasers require a water jacket.
Uses for Argon Gas Lasers
- Medicine uses the argon gas laser to remove soft tissue in a process similar to industrial laser drilling. The laser cauterizes as it burns, minimizing bleeding. Ophthalmologists use argon gas lasers to repair damage within the eye. The light produced by the argon gas laser passes through the liquid inside the eye without damage and is absorbed by tissue on the other side. Other lasers use argon gas lasers as a secondary energy source to increase the strength of their laser beams.