When we think of lasers, we may conjure up something seen in the movies. Lasers, however, can be found in real-world industry, making slicing and transforming objects much simpler in industry. In laser material processing, a laser will strike a target and changes to that object will happen, such as through the soaking up of photons, which are particles of light emitted from the laser. These photons will be changed into heat energy.
How a Laser Works
Lasers are the instruments that manipulate how highly stimulated atoms release photons to create a stream of light. There are only three things that can occur when a laser connects with a material. The laser beam will either be reflected, sent, or it will be absorbed into the object. Sometimes two or three of these events, such as transmission and absorption, may happen at the same time. The beam will be a certain wavelength and a certain color as well as compact and concentrated, unlike beams of light encountered in everyday life. If most of the beam is soaked up into an object, which is most often the case in laser material processing, the main characteristics that have to be taken into account are the average strength the laser beam has, its intensity on the object it hits, and its wavelength. Intensity on a basic level is the brightness of the laser beam. The wavelength is the sequence of waves the photons produce. Think of a rippling water wave, the photons are fluctuating in the same type of wave. The average power of a laser beam is quantified in watts (W). Lasers all have an active medium that takes in energy. The medium can be made of either a solid crystal-like material, liquid, gas (such as in a CO2 laser), or a diode, and holds the atoms absorbing the energy. A laser also has to have a method to make the atoms become energized. This might be a light source, for example.
The optical resonator is a pair of mirrors in the laser system. One of the abilities of a laser is to pump up the atoms to get them excited. This is accomplished by pumping up what is called a lasing medium inside the laser. At each extreme of the lasing medium is a mirror. Photons reflect off of both of them and energize other electrons to emit even more photons. The mirror at one extreme allows some light through, which forms what is known as the laser beam. Getting the atoms pumped up involves getting their matching electrons at a advanced level of energy. The energized electrons that first absorbed energy to get excited can now give off energy as light energy, or a stream of photons.
Laser Classifications
Lasers are classified according to the characteristics of average power, wavelength, and intensity. This implies they are either solid-state, liquid, gaseous, or semi conductor lasers. Solid-state are lasers with material that is optically see-through and the active medium is solid. Liquid, or dye lasers have a medium that is liquid and they can operate with pulsing or continuous wavelengths. Gaseous lasers have a medium of gas. Examples of gas lasers are CO2 lasers and neon signs found in store windows. And the fourth group is semi conductor or diode lasers that are the most common type of laser.
Lasers and Cutting Applications
Using CO2 lasers as an example, carbon dioxide gas atoms become energized at a low pressure between two mirrors. One of the two reflective mirrors lets some of the beam leak through. They make a huge amount of heat. The light output is at the end of the infrared spectrum. Having a beam of high quality is paramount, especially in cutting. Lasers cut via the beam of light the laser makes. The beam starts by melting what is in front of it or sometimes vaporizing the material. Slicing happens when the beam has cut through the object. There are various types of lasers designed to slice various types of materials. CO2 lasers have high absorption rates, and are often used in the cutting of plastics, wood, stainless steel, carbon steel, aluminum, and other metals such as titanium. CO2 lasers actually have more than CO2; they have a mixture of gases including helium (He) and nitrogen (N2). Nitrogen will cut up to inch thick stainless steel as well as aluminum. Oxygen is able to slice carbon steel. Laser cutting advantages include no wear and tear on machinery, are faster than using other options for cutting, and can slice through physically thicker material objects.
Lasers have applications from communications in data storage to the medical field. They have revolutionized methods of conducting surgery as well as methods in industry. It is exciting to see what is in store for cutting applications with lasers in the future.
Marc Anderes is the VP of Operations of Maloya Laser which specializes in Laser Cutting and Metal Manufacturing with advanced laser technologies, for aerospace, medical, machinery, scientific and transportation needs.