Nd: YAG Laser - Really Stand the Test of Time
The Nd: YAG laser crystal was developed shortly after the invention of the ruby laser in the 1960s. Of all the solid-state laser crystals, it's stood the test of your time best. Its high gain, narrow linewidth, low threshold, and physical properties make it the foremost versatile laser material for a spread of applications.
The ubiquitous Nd: YAG laser has played many roles over the years. For the military, it's provided rangefinding and target designation capabilities. When used with nonlinear optics or as a pump source for other lasers, it offers scientific users diversity in pulse width format and lasing wavelength. Other applications include medicine (dermatology and ophthalmology), materials processing (cutting, trimming, welding, and surface cleaning), and commercial instrumentation (ablation, spectroscopy, marking, nondestructive testing, and lightweight shows). Nd: YAG lasers and their harmonic version are used under harsh environmental conditions for remote sensing, gated imaging illumination, bathymetry, ocean, and atmospheric studies, and lots of other real-world applications that need compact, rugged sources.
In a number of these application areas, Nd: YAGs compete against nonphotonic techniques and other lasers, like CO2 and high-power diode lasers. But the Nd: YAG offers a wider application range, in large part due to its unique properties and since it's one among the few lasers that operate efficiently with either flashlamp or diode pump and in pulsed or continuous-wave (CW) mode.
Nd: YAG may be a man-made cubic garnet crystal (Nd: Y3Al5O12) grown by the Czochralski method. A high-purity oxide powder compound of aluminum, yttrium, and neodymium (the active dopant ion that substitutes into yttrium sites with a doping level of about 1 percent) is first placed during an iridium crucible and melted in a frequency furnace at about 1970 °C. A seed crystal is then brought into contact with the liquid surface. When slowly lifted, rotated, and cooled slightly, a high-quality, single-crystal boule of neodymium-doped yttrium aluminum garnet (Nd: YAG) emerges at the speed of about 0.5 mm per hour.
Typical crystal boules are 60 to 80 mm in diameter by 175 to 225 mm long. Rods, wafers, and slabs in various geometries are extracted from the boule then fabricated, polished, and coated to customer specifications (Figure 1). Finished products range from diode-pumped laser rods as small as 0.5 mm in diameter by 25 mm long to slab geometries as large as 8 × 37 mm in cross-section by 235 mm long. quite two-thirds of Czochralski's growth station volume within the US is in Nd: YAG, making it the foremost widely used laser crystal. Other YAG crystals being grown in the volume are Er: YAG and CTH: YAG.
The most common Nd: YAG rod geometry may be a right circular cylinder, although slabs, wafers, and rectangular shapes sometimes are used. The rod end faces usually are polished flat and parallel (or oriented near Brewster’s angle for low transmission loss without optical coatings). Convex radiused rod faces sometimes are wont to catch up on thermal lensing. In its simplest form, the resonator comprises the rod with a highly reflective dielectric coating at one end and a partial reflector (out coupler) at the opposite. the top faces must be precisely parallel during this case. The more typical configuration uses separate mirrors at each end of the resonator alongside other optics and crystals added to polarize, modulate, Q-switch, and redirect the beam, select net lens power, convert wavelength and spectrally separate its output or a mixture of those effects.
The resonators are often stable or unstable. Most scientific lasers use graded-reflectivity mirrors to supply beam divergence, moderately high energy, and thus high brightness. Many commercial applications don't require a tightly focused spot, and therefore the more conventional multimode stable resonator often is employed. rock bottom order stable transverse mode, TEM00, features a smooth, Gaussian spatial beam profile in both the near and much field. Most stable resonators are operated multimode; power (or energy if pulsed) is far higher because the lasing diameter is often larger than if confined to the only TEM00 mode. the appliance dictates the selection of single- vs. multimode operation.
CW Nd: YAG lasers of quite 5 kW and flashlamp-pumped lasers of quite 20 J are built. Almost any pulse width from ultrashort to CW is feasible. electro-optically Q-switched, pulse-pumped Nd: YAGs typically produce 5- to 20-ns pulse widths. Lower gain, acousto-optically modulated CW-pumped Nd: YAGs produce 150- to 300-ns pulses. Relatively simple oscillator-amplifier configurations can produce 1 to 2 J of Q-switched energy at 1064 nm.
Limitations arise due to the high gain (parasitic effects) and safe operating fluence. Active mode-locking schemes allow pulse widths from a couple of fractions of a nanosecond right down to a few picoseconds. Shorter pulse durations require lasing media with higher gain-bandwidth like Ti: sapphire. Non-Q-switched long-pulse lasers can also produce pulse widths of 100 ms or more. This diversity in pulse duration makes it possible to deliver a good range of peak power density to suit specific applications.
The diode-pumped Nd: YAG laser has opened a wider range of applications, because of its increased source stability, efficiency and lifelong, and reduced power consumption and size. Commercial Nd: YAG lasers with repetition rates above 100 kHz are now available. Diode-pumped devices are best fitted to low-pulse-energy or CW power applications because the worth of diode bars/arrays still is far above that of linear flashlamps.
Frequency-doubled to the green at 532 nm, tripled to the blue at 355 nm, and quadrupled to the deep blue at 266 nm are other key Nd: YAG wavelengths. The 532 nm wavelength is right for pumping Ti: sapphire or dye lasers (in liquid or plastic matrix form). Noncritically phase-matched KTP optical parametric oscillators (OPOs), when pumped with a Q-switched Nd: YAG at 1064 nm, efficiently generate 1.57-µm radiation, a more eye-safe wavelength to be used in less controlled areas. The laser also has lower gain wavelengths near 1.32 and 1.44 µm and 946 nm which will be frequency-doubled, frequency-mixed, or Raman-shifted to supply visible and near-IR wavelengths for specialty applications. the range in wavelengths when coupled to nonlinear optics and OPOs is exclusive.
People also ask
1) What is ND YAG laser used for?
Nd:YAG lasers are used in ophthalmology to correct posterior capsular opacification, after cataract surgery, for peripheral iridotomy in patients with chronic and acute angle-closure glaucoma, where it has largely superseded surgical iridectomy, for the treatment of vitreous eye floaters, for pan-retinal.
2) What is YAG laser for face?
How does the nd: YAG Laser Work? This Q-switched laser offers rapid pulses that can effectively shatter ink in tattoos or melanin in some types of skin pigmentation. The laser targets the ink or melanin without harming surrounding skin and tissue, reducing discomfort, side effects, and downtime.
3) Which type of laser is Nd YAG laser?
Neodymium-doped Yttrium Aluminum Garnet (Nd: YAG) laser is a solid state laser in which Nd: YAG is used as a laser medium. These lasers have many different applications in the medical and scientific field for processes such as Lasik surgery and laser spectroscopy.
4) Is Nd:YAG laser safe for face?
Conclusion: The long-pulsed 1064-nm Nd:YAG laser with contact cooling is a safe and effective method of hair reduction in patients of all skin types. Side effects were limited and transient.
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