Shots of a laser head seen from the inside
Lasers are everywhere around us. From the industrial world(automotive, tooling, hydraulics, home appliances), to the medical world to the aesthetic world, lasers are now used in virtually every field because they are versatile and can perform a variety of tasks: laser cutting, welding and marking, tattoo removal, eye surgeries, hair removal, and so on.
Of course, all lasers are not the same, and depending on the application, the most suitable one with the most appropriate source for the purpose is chosen.
Lasers are classified into five categories:
In addition, these five types of lasers can be divided into subcategories based on their mode of operation: continuous wave lasers and pulsed lasers. In addition, there are also different types of pulsed lasers. The same fiber laser dedicated to marking can have variable pulse duration (MOPA version) for mark plastics without smearing and burning. Before delving into the different types of lasers, let’s define what a laser is and how it works.
A laser is a device that generates light in the form of a laser beam. A laser beam is different from a light beam in that its beams are monochromatic (one color), coherent (of the same frequency and waveform) and collimated (going in the same direction). Lasers provide this “perfect information,” which is ideal for applications requiring high precision. In this article we discussed the History of lasers , from Einstein to Gordon Gould. Let us look technically at the components of a laser. In a laser we find three main components:
The energy source pumps light into an active medium (the active medium is the resultant stimulated emission of photons through electronic or molecular transitions to a lower energy state from a higher energy state previously populated by a source). It varies depending on the type of laser. It could be a laser diode, an electric discharge, a chemical reaction, a flash lamp, or other types.
The active medium emits a beam of light of a specific wavelength when excited by light. It is said to be the source of optical gain. Lasers are generally named after their gain medium. In a CO2 laser, for example, the gain medium is CO2 gas.
The resonator amplifies optical gain through mirrors surrounding the gain medium. These include bulk mirrors in solid-state lasers, cut or coated facets in laser diodes, and Bragg reflectors in fiber lasers.
The Nd: YAG laser was introduced to the market almost 30 years ago and is perhaps the most famous and well-known laser in the industry. This is because of the large number of applications it covers. Originally these lasers were pumped by lamps. Later they evolved, replacing lamps with diodes. Diode-based systems are robust with excellent expected life. An advantage of Nd: YAG lasers is the quality of the laser beam. This is due to the small spot size. This, combined with short pulses, produces high peak power that can be useful in deep engraving with sharp, clear marks and small characters.
Vanadate lasers can emit at three different wavelengths: 1064, 532 (green) and 355 nm (blue). Vanadate lasers are also diode-pumped and are particularly suitable for ablation process and heat-affected area applications. One of the major fields of application of vanadate lasers are the Day&Night markings. In this case, the laser removes the surface coating of the component (usually they are car interior buttons) exposing the underlying surface with the functional marker.
Since these buttons are backlit, their effect is what we are all familiar with on the stereo, window, and air conditioning buttons.
With the advent of the fiber laser, there has been a real revolution in the world of lasers and marking. The fiber laser has become the center of every application and has been tested and perfected to fit almost every market demand.
Its effectiveness is remarkable especially in the laser marking of metals.
One thing to keep in mind is that the output power of all solid-state lasers degrades over time, but it is possible to calibrate the system to maintain the same power in the laser as the day it left the factory. This will allow the laser to maintain the same sign quality and speed as the day it arrived and was put into production.
The wavelength of the fiber laser is 1064 µm, with an extremely small focal diameter. This leads to an increase in intensity, which is 100 times greater than that of CO2 lasers, at the same average output power.
A Gaussian beam has an M²of 1 and allows for a smaller spot relative to the wavelength and optics used. The best beam quality possible in Nd: YAG and vanadate laser marking systems has an M²of 1.2. Fiber-based systems generally have an M²value of 1.7. This means a larger spot size and lower power density. Better beam quality means finer lines, sharper contours, higher marking speed (because of the higher power density), and deeper engraving.
YAG and vanadate lasers are very different from fiber lasers in terms of peak power and pulse repetition frequency range. The pulse duration can be adjusted in the case particular fiber systems such as the MOPA laser.
Industrial CO2 laser is a laser in which an electric current is sent through a gas to generate light through a process known as population inversion. Examples of gas lasers include carbon dioxide (CO2) lasers, helium-neon lasers, argon lasers, krypton lasers, and excimer lasers.
Gas lasers are used in a wide variety of applications, including holography, spectroscopy, barcode scanning, air pollution measurements, materials processing, and laser surgery.
CO2 lasers are probably the best known gas lasers and are mainly used for laser marking, laser cutting, and laser welding. LASIT, with the FlyCO2, realizes markings on organic materials such as wood and bamboo, which are particularly useful in the Promotional sector.
The solid-state laser is a laser whose active medium is a crystal or glass doped with ions, thus differentiating it from the dye laser, which uses an organic dye, usually in liquid solution, as the light-amplifying medium, and the gas laser, in which an electrical discharge is produced through an appropriate gas (e.g., helium-neon) to produce the coherent light.
A fiber laser is a special type of solid-state laser that is a category of its own. A fiber laser is a device in which “the active gain medium is an optical fiber doped with rare earth elements such as erbium, ytterbium, neodymium, dysprosium, praseodymium, thulium and holmium.”
The light guiding properties of fiber optics are what makes this type of laser so different: the laser beam is smaller than in other types of lasers, making it more precise. Fiber lasers are also renowned for their small footprint, good electrical efficiency, low maintenance, and low operating costs.
Fiber lasers are used in a wide range of applications, including materials processing (laser cleaning, texturing, cutting, welding, marking), medicine, and directed energy weapons. In this article we discuss the advantages of fiber lasers for laser marking, while in this article we delve into the difference between a Fiber laser and its variable pulse duration (MOPA) version.
Today, the fiber laser is the most widely used laser marking and engraving application. This is because it has a long-lasting, high-quality effect on all metals and almost all plastics. With this type of system, we are also able to guarantee very black, reflection-free markings, which are especially required in the medical field (for safety reasons) and in the home appliances e Jewelry (for aesthetic reasons).
Another type of laser that is distinguished by its pulse duration is the Picosecond laser. With the FlyPico, we are able to obtain very high-contrast, glare-free black markings. This is particularly useful in the medical world (for safety reasons) and in the home appliance and jewelry world (for aesthetic reasons).
Liquid lasers use an organic dye in liquid form as a gain medium. They are also known as dye lasers and are used in laser medicine, spectroscopy, birthmark removal, and isotope separation.
One of the advantages of dye lasers is that they can generate a much wider range of wavelengths, making them good candidates for being tunable lasers, which means that the wavelength can be controlled during operation.
In laser isotope separation, for example, lasers are tuned to specific atomic resonances. They are then tuned to a specific isotope to ionize the atoms, making them neutral rather than negatively or positively charged. They are then separated with an electric field, resulting in what is called isotopic separation.
A laser diode (or LD, from Laser Diode in English) is an optoelectronic device capable of emitting a laser beam emitted from the active region of the semiconductor from which the device itself is made. The structure of the semiconductor is very similar to that used in making LEDs (Light Emitting Diode).
A laser diode, like many other electronic devices, is composed of doped semiconductor material present on a very thin layer on the crystal surface. The crystal is doped to produce an n-type semiconductor region and a p-type semiconductor region, one on top of the other, to make a PN junction, that is, a diode.
As in other types of diodes, when the structure is directly polarized, the gaps from the p region are injected into the n region, where electrons are the majority charge carriers. Similarly, electrons from the n region are injected into the p region, where the gaps are the majority carriers. Quando un elettrone e una lacuna sono presenti nella stessa regione, possono ricombinarsi per emissione spontanea, cioè l’elettrone può rioccupare lo stato energetico della lacuna, emettendo un fotone con un’energia uguale alla differenza tra gli stati dell’elettrone e della lacuna coinvolti.
These injected electrons and gaps represent the injection current of the diode, and the spontaneous emission gives the laser diode below the laser threshold LED-like properties. Spontaneous emission is necessary to initiate laser oscillation, but it causes inefficiency once the laser is oscillating.
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Public Relations Manager | LASIT
Public Relations Manager at LASIT since 2019, Claudia Neri is responsible for managing the Marketing and Communications department. She handles the company’s communication strategy, coordinating public relations, brand promotion and institutional communication activities for the Italian and international market.
