A fact sometimes overlooked about lasers is that the word itself is an acronym — standing for Light Amplification for Stimulated Emission of Radiation. The key details in this name tells us how unique it is as a light source, producing a much narrower beam than a torch or a light bulb. So what’s the science behind this fascinating phenomenon, and what role does it play in everyday life? Beyond laser pointers and barcode scanners, this article will explore how laser technology finds its way into industrial applications you may not have expected.
What is a laser?
To understand lasers first we have to grasp what wavelengths are. Simply put, they describe the horizontal distance between two peaks of a wave of light — named because of how they resemble those of the ocean, with light’s peaks and valleys, or crest (highest point) and trough (lowest point). Light travels in seven different types of wavelengths, such as infrared or ultraviolet, for instance, which make up a spectrum. Red light, for instance, has a much longer wavelength than blue light.
Lasers, however, do not occur naturally on this spectrum. They operate at quantum levels, meaning at the scale of atomic and subatomic particles. Lasers are created by changing the behaviour of the parts of the atoms that absorb and radiate light particles — otherwise known as photons. As NIF explains, “a laser is created when the electrons in the atoms in optical materials like glass, crystal, or gas absorb the energy from an electrical current or a light”. With this additional energy, the electrons are stimulated to increase the power with which they orbit the atom’s nucleus.
While visible light is made up of various wavelengths, these are deemed ‘incoherent’ because they move in different directions and frequencies. When the energized electrons are transmitted through a gain medium (made from glass, or gas), they generate light that “travels in the same direction, and at the same wavelength”, thus producing narrow beams of radiation — the laser.
How lasers work
To emit a laser requires materials like an optical cavity. This is an arrangement of mirrors inside a very small chamber, which is used to reflect light. A material that generates electromagnetic radiation (the energy that travels at the universal speed of light) goes inside a cavity with a dual-mirror system at either end of it. That way, the reflections bounce off each other to amplify light signals, which then travel through a transparent lens.
What are industrial lasers?
Despite their immediate association with a mischievous laser-pointer, or as a far-fetched device in science fiction or action thrillers, we forget how lasers are present in many uses in everyday life. They have numerous applications across different industries, whether in eye surgery (or the fated tattoo-removal operation), video games, or merely the laser scanner barcodes in the supermarket.
But there is also the next level of laser applications, which, in some ways, ironically draws a comparison with their more exciting and fantastical counterparts found in Star Wars and James Bond. They are, in fact, widely applied in manufacturing. For example, in laser material processing, they are used to cut, weld and mark products like smartphones and cars. Fibre-optics for broadband technology are also made possible by industrial lasers that have a “uniform phase”, producing a smooth light wavelength that does not disperse, making for the fastest possible communication.
The most common industrial laser uses CO2, and is categorized into two distinct groups: axial-flow lasers, and diffusion-cooled lasers.
Axial-flow lasers circulate CO2 gas through their container or arc tube. This removes byproducts, cooling the gas to ambient temperatures (relative to its immediate surroundings) externally. Through simple electrical discharges, they cause carbon dioxide gas to emit light, creating small and powerful beam outputs, which are regularly used for welding or cutting industrial materials.
These lasers similarly use a process of cooling to emit their light. However, they employ radio-frequencies (RF), which are electromagnetic waves generated when alternating current goes through a conductive material. These transfer electricity into CO2 gas, with the mixture sandwiched in a narrow gap between two extended electrodes (electrical conductors). The laser then exits this cavity through a miniscule window. Hot gas molecules transfer their energy to the water-cooled electrodes, removing heat.
These lasers provide the highest levels of output available, but this requires RF power solutions — in other words, a system that can generate these electromagnetic waves. They can then produce “high quality, stable and repeatable” lasers that can “adapt to cutting-edge manufacturing”, according to XP Power.
The future of lasers
As INDUSTR pithily described, the laser is now “the smartphone of industrial tools”. While we have established in this article the science behind these wondrous rays of light, artificial intelligence is also being used to develop new forms. Though electromagnetic technology has been applied to power electric vehicles, manufacturers are persistently toying with new ways to hone the building process of these cars using the advanced welding capabilities of laser mechanisms. What’s more, fibre lasers are also being utilised in the vehicle batteries themselves, using a more flexible Adjustable Ring Mode (ARM) technology.
Although laser equipment is already used to help eliminate cancerous tumours, researchers at Queens’ University Belfast have developed “high intensity, high contrast laser pulses” as part of the cutting-edge Gemini Project. They have demonstrated that using short, intense bursts could lead to diminished side effects and more successful treatment.