Laser Cutting Part 2
Laser technology has the capacity to excite atoms through several methods, which provides the opportunity to create different types of lasers. Though theoretically an amazing array of laser types can be constructed, at this time only a few kinds of lasers can be created in the real world. The most common types of lasers are solid-state, gas, liquid dye, semiconductor, and fiber.
A laser is essentially a light beam. However, unlike the light beams we are accustomed to, such as those from a lamp of flashlight, laser light is far more concentrated, which is why lasers are a single color, such as red or green.
Typical white light lacks color because the photons (packets of light) that create it exist on different wavelengths and hence have different colors. The mix of colors results in white. Laser photons are all of the same wavelength, or color, so they combine together to create a far more powerful light of a single color. It is owing to this increased power that some lasers can cut through steel.
Light can be a mighty force when concentrated into a laser. Let’s look at how different types of lasers work to create the power that does everything from cut metal to play DVDs.
The Three Main States of Matter
Solid, gas and liquid are some of the most common types of lasers because they are the three main states of matter. In other words, the same type of matter can exist in any of these three states, depending upon the condition it is exposed to.
To visualize matter in different forms, imagine an ocean beach just after a snowstorm. In this scene, water exists in all three forms. The ocean is water in liquid form, while the snow on the beach is H2O in its solid form. Above, we see water in the clouds existing as vapor, or a gas.
These states of matter are part of nature. Because they are all prevalent here on Earth, we can use either of these states of matter to make laser beams.
To create a laser, we need a medium. A medium is a collection of atoms that are excited in order to create the light (photons) that become the laser beam. Mediums can be solids, liquids or gases.
To create solid-state lasers, the medium needs to be something solid. Common solids used in these types of lasers include ruby rods or other crystalline materials.
For the medium to produce a laser beam, it must be “doped”. The doping process replaces some of the medium’s atoms with ions, which are charged particles. These charged particles provide enough energy for laser light of a precise frequency, the frequency that corresponds to the desired color and power of the laser.
Solid-state lasers have flashtubes wrapped around the medium. When activated, these flashtubes fill the medium’s atoms with energy. The result is a high-powered laser beam that usually emits light in brief pulses.
By contrast, gas lasers produce a continuous laser beam that is both powerful and efficient. For this reason, they are used in industrial cutting applications and welding.
Gas lasers employ noble gases or Co2 as their mediums. Electricity is pumped through the gas medium to excite the atoms and create the laser beam.
These lasers use organic dye molecules as their medium, which are mixed into a solution. A flash lamp or even another laser interacts with the solution, resulting in the laser beam. Liquid dye lasers emit a broader light band versus solid-state and gas lasers. Because of their broader light band, they can be programmed to produce different frequencies, providing flexibility unavailable in solid-state and gas lasers.
Semiconductor and Fiber Lasers
These types of lasers are in a different category because their mediums are not one of the natural states of matter.
Semiconductor lasers are a cross between LED (light emitting diode) lights and the traditional lasers we previously discussed. LEDs make light because they stimulate electrons to join with “holes”, which are essentially missing electrons.
Laser diodes take it a step further versus LEDs. Electrons enter the diode and combine with holes, and some of the excess energy becomes photons. These photons interact with more incoming electrons, which in turn produces more photons. This self-perpetuating process is known as resonance. The resonance increases the power of the light and produces it in a uniform color, as do conventional lasers.
Semiconductor lasers power many electronic devices, including CD players, laser printers and bar code scanners.
Fiber lasers work due to “doped” fiber optic cables, which function as the medium. These cables then “pipe” the laser light where it is needed.
Laser light is an amazing technology that has introduced everything from laser welding to laser printing. By using different mediums, engineers have been able to create the diverse types of laser light that make these scientific advances possible. Over time, it is possible that new types of lasers will be invented that will further enhance everything from industrial production to surgery.
Prototech Laser located in Chesterfield MI, is a national leader in laser cutting and metal fabrication services. With over two decades of laser and program management expertise, our full-service offerings include state of the art laser, plasma cutting, forming, machining, welding and more.