Laser Systems
One type of laser system, the visible laser, emits light with a wavelength in the visible spectrum, which may be red, green, violet or blue. Most lasers are defined by their lasing medium; some are gases like neon or CO2, some are liquid and others solids like crystals or glass. CO2 lasers and helium neon lasers use gas as the lasing medium. Dye lasers use a dye solution, which is liquid, and solid state lasers like YAG and diode lasers, which are semiconductor lasers, use a solid material as the lasing medium. Depending on the strength of the laser, there are many different applications across the medical, manufacturing, construction and electronics industries. The weakest lasers are used as pointers, leveling tools and surveyors. The medical industry uses them for surgeries and optical procedures. The most powerful lasers are used in material fabrication and cut, weld, etch, engrave and heat treat non-reflective metals and plastics.
All lasers, visible or infrared, are divided into different classes, which are based on their power and heat. Class I lasers are the weakest kind and pose zero biological hazard. They are less than 1mw. Class II lasers are also safe to use and unless focused on the retina for long periods of time won't cause optical damage. They are powered up to 1mw. Class IIIa lasers are a little more dangerous. At 1 to 5mw, eye injury is possible, but they will not burn any materials. IIIb, 5 to 500mw, will cause eye damage and may burn materials. They are equipped with many safety features. Finally, class IV lasers are the most dangerous at 500mw or more. They burn any material on contact, including human skin and hard metals. They must have a key lockout switch to ensure only authorized personnel operate them, as well as several warning labels and a timer that allows personnel to move out of the way of the laser before operation. Most lasers consist of 3 components: an optical cavity, lasing medium and pumping system. The optical cavity contains the lasing medium and a series of mirrors that increase the beam's intensity and direct it to a certain point. The pumping systems may be optical, which uses photons, collision, which transfers energy by an electrical discharge and binding energy, which is released in chemical reactions.
