The term laser is an acronym; it stands for Light Amplification by Stimulated Emission of Radiation. In other words, when stimulated, lasers release a beam of electromagnetic energy that manifests as monochromatic, coherent light. Though they are now quite advanced, the road that lead to the invention of the laser was walked not very long ago; it began with Einstein’s paper, On the Quantum Theory of Radiation, a thought process which was researched and built upon into the 1950s.
The laser itself, however, was officially invented only within the last sixty years; the first one was built in 1960 by Theodore H. Maiman, who based his work on the theoretical works of Arthur Leonard Schawlow and Charles Hard Townes. Within the last sixty years, the capabilities of the laser have made great strides.
Today, industrial lasers are very powerful, used for a number of highly technical and highly sensitive applications, including surgery and skin treatments, optical disc drive reading, printing, materials cutting and welding, free-space optical communication, barcode scanning, and DNA sequencing. Read More…
Highly concentrated, laser beams may be visible or invisible, depending on the wavelength they emit. Visible laser beams emit light using a wavelength from the visible spectrum, which includes wavelengths that are red, green, violet, and blue. Invisible beams, on the other hand, are generated from infrared wavelengths, which are longer than those in the visible spectrum and cannot be seen.
Lasers can be categorized in a number of ways; one of them is by power output. Lasers are divided into five classes based on power output, and these class assignments help operators understand their level of safety or lack thereof, and how to proceed with safety measures. With maximum power at less than 1 milliwatt (mW), Class I lasers are the weakest and are completely safe to use.
Lasers in this class mostly serve as pointers. One level up are Class II lasers, which produce power up to 1 mW. Mostly safe, they only threaten eye tissue damage to those who focus the laser at their eye. As lasers climb to level IIIR (formerly IIIa), they begin to pose a threat to careless users. Operating between 1 and 5 mW, they can cause eye injury but they will not burn anything. Class IIIb lasers can display power anywhere between 5 and 500 mW. With this level of power, they have many more applications, including with CD-ROM drives, DVD players, DVD-ROM drives, high speed CD and DVD burning, and the physical burning of thin plastics.
With the added ability to burn some materials, Class IIIb lasers are more dangerous than the last. The highest class of lasers, Class IV, presents users with the most risk of injury and accident. Operating at 500 mW and above, they can burn any material they touch, including hard metals and human skin. To protect users, all lasers operate inside enclosures that limit access to them by unauthorized personnel. Class IV lasers are further regulated with a master switch, and shielded from those around them with a permanently attached beam stop or attenuator, which greatly reduces beam emission when a laser is on standby.
Regardless of their class, all lasers consist of an optical cavity, a gain medium, and a pumping system.
The optical cavity, also called a resonating cavity or an optical resonator, consists of a pair of mirrors, placed on either end of the gain medium so that light, or photons, can bounce back and forth and steadily amplify.
Said gain medium is a mechanism made up of materials that allow it to amplify light and energize the laser. The medium may be made of any number of materials, but some common options include liquid dyes, semiconductors, solids, or gases like argon.
In order for the gain medium to work, it needs energy. It receives the energy it needs via the pumping system, which transfers energy either via collision pumping, optical pumping, or chemical reaction. In collision pumping, energy is transferred by an electrical discharge inside a pure gas or gas mixture media. Optical pumping, on the other hand, gets energy from outsourced photons, such as those existing in a xenon gas flash tube. The last method uses the binding energy released in chemical reactions to raise media to a lasing state.
Industrial lasers are also defined by their gain medium, or lasing medium. They may be broadly classified as solid state lasers, dye lasers, gas lasers, and semiconductor lasers.
Under the umbrella of solid state lasers exist fiber lasers, which use materials like glass or crystal and neodymium-yttrium aluminum garnet lasers, or ND:YAG or YAG lasers, for short.
Dye lasers use complex organic dyes in suspension or liquid form to reach a wide range of wavelengths.
There are many different types of gas lasers, the most common including CO2 lasers, helium lasers, helium-neon lasers, and excimer lasers. Excimer lasers use a mixture of reactive and inert gases as their lasing medium; examples include chlorine or fluorine and argon, krypton or xenon, respectively.
Finally, semiconductor lasers, also called diode lasers, use electrical power as their medium. Usually, they are small and low in power, used in appliances like CD players and laser printers.
No matter the application, there is a laser out there that will do the job. From pointing, surveying, and leveling, to etching and engraving, to bloodless surgeries to guided missiles, lasers offer dependable, low maintenance solutions that, with the proper safety precautions, are relatively risk-free.