The following table shows the differences in oscillation form, output, and conversion efficiency between each medium.
You can find more information on our web, so please take a look.
The oscillation form of a laser can be either pulsed or continuous. Pulse oscillation lasers generate a pulse wave by controlling (through light modulation) the intensity, wavelength, and phase of the laser beam. Methods for generating a pulse also include controlling the Q value of the laser oscillator as with Q-switch lasers. The &#;Q value&#; is the ratio of energy consumed in each cycle to the accumulated energy. This value can be expressed by the following formula.
Q = (2π / Accumulated energy) / (Energy consumed per cycle)
The shape of the weld bead also varies for each oscillation form, as shown below.
Pulse oscillation (P)
Continuous wave (CW)
Lasers are everywhere around us. Surgeons use them for eye surgery and cancer treatments. Manufacturers use them for material processing to cut, mark, weld, clean, and texture various types of materials. Some people need them for tattoo or hair removal, and everyone has seen laser light shows during music concerts. More recently, new applications like laser holography are emerging.
Different types of lasers are needed for these applications. Based on their gain medium, lasers are classified into five main types:
Additionally, these five types of lasers can be divided into subcategories based on their mode of operation: continuous-wave lasers and pulsed lasers. Furthermore, there are also multiple types of pulsed lasers.
Before differentiating the types of lasers, it&#;s good to remember what a laser actually is.
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 rays are monochromatic (a single 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 that require high precision.
Lasers are comprised of three main components:
A gas 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, material processing, and laser surgery.
CO2 lasers are probably the most widely known gas lasers and are mainly used for laser marking, laser cutting, and laser welding.
Solid-state lasers use a solid (crystals or glasses) mixed with a rare earth element as their source of optical gain. The mixed element is typically neodymium, chromium, erbium, thulium, or ytterbium.
The most known solid-state laser is the ruby laser, since it is the first laser ever constructed. The Nd:YAG laser (neodymium-doped yttrium aluminum garnet) is also common in material processing applications.
Solid-state lasers are also used for LIDAR technology as well as various medical applications, including tattoo and hair removal, tissue ablation, and kidney stone removal.
A fiber laser is a special type of solid-state laser that is a category of its own. In fiber lasers, the gain medium is an optical fiber (silica glass) mixed with a rare-earth element.
You will get efficient and thoughtful service from Easetak.
The light guiding properties of the optical fiber are what makes this type of laser so different: the laser beam is straighter and smaller than with 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 range of applications, including material processing (laser cleaning, texturing, cutting, welding, marking), medicine, and directed energy weapons.
Examples of fiber lasers used for these applications include ytterbium and erbium-doped fiber lasers.
A Liquid lasers use an organic dye in liquid form as their 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 to be tunable lasers, meaning that the wavelength can be controlled while in operation.
Photo Courtesy of Wikimedia Commons
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 as opposed to negatively or positively charged. They are then separated with an electric field, achieving what is called isotope separation.
Laser diodes, also called diode lasers and semiconductor lasers, are similar to regular diodes in that they have a positively-negatively (PN) charged junction. The difference is that laser diodes have an intrinsic layer at the PN junction made of materials that create spontaneous emission. The intrinsic layer is polished so that the generated photons are amplified, ultimately converting the electric current into laser light.
Photo Courtesy of Wikimedia Commons
Although most semiconductor lasers are diode lasers, a few of them are not. This is because there are semiconductor lasers that do not use the diode structure, such as quantum cascade lasers and optically pumped semiconductor lasers.
Like fiber lasers, laser diodes can be classified as solid-state lasers since their gain medium is solid. However, they are in a category of their own because of their PN junction.
Laser diodes are often used as energy sources to pump other lasers. These lasers are referred to as diode-pumped lasers. In these cases, laser diodes are typically arrayed to pump more energy, as shown in the following image.
Laser diodes are extremely common. They are used in barcode readers, laser pointers, laser printers, laser scanners, and several other applications.
All types of lasers can operate using one of two methods: their laser beams can either be pulsed or continuous. This is what we call their mode of operation.
Continuous-wave lasers may seem more powerful than pulsed lasers because the advertised laser power is typically much higher, but this can be misleading. This is because lasers are named according to their average laser power, and the average power of pulsed lasers is usually lower even if they reach higher peaks of power.
For example, a 6,000W continuous-wave laser continuously releases 6,000W of laser power. Conversely, a 100W pulsed laser can release pulses of 10,000W each.
Pulsed lasers are divided into several categories based on the duration of their pulses.
A modulator is used to control the number of pulses per second. As a result, each pulse has a precise duration, called pulse duration, pulse length, or pulse width. The pulse duration is the time between the beginning and the end of a pulse.
Several modulating methods are used to pulse laser beams: q-switching, gain-switching, and mode-locking are some examples. The shorter the pulse, the higher the energy peaks. Here are the most common units used to express pulse duration.
As you can see, there are many ways to categorize lasers. Another way is by the laser wavelength, where you have infrared, near-infrared, visible, ultraviolet, and X-ray lasers.
Laser experts keep pushing the limits of laser technology, with new developments being made every year. As a result, the types of lasers are constantly evolving, and anyone looking to explore this world can expect a lifetime of discoveries.
Want more information on Semiconductor Neck Laser Instrument? Feel free to contact us.