1. Nd: YAG
Nd: YAG crystal, fully known as neodymium-doped yttrium aluminum garnet crystal (Nd: Y3Al5O12), yttrium aluminum garnet crystal as its activator, the content of Nd atoms in the crystal is 0.6 ~ 1.1%, comes from the solid laser, can delight pulse laser or constant laser, releasing laser infrared wavelength 1.064 μm.
Brief pulse Nd YAG laser has crucial applications in laser processing, photoelectric countermeasures, laser varying, laser communication, and so on. Especially the peak power laser gotten by Q switching is the core device in much sophisticated clinical research and also modern scientific tools as well as tools.
Neodymium-doped yttrium aluminum garnet (Nd: YAG) laser crystal has the advantages of good optical uniformity, mechanical properties, high physical as well as chemical security, great thermal conductivity, and so forth. It has become the primary assistance product for armed forces solid laser modern technology and also the application instructions of tool as well as high-power lasers. It is called one of the “three basic laser crystal products”, which is extensively made use of in commercial, medical, army, and clinical research.
(1) Benefits
Nd: YAG crystal is still one of the most extensively utilized strong laser tools as a result of its exceptional optical and also mechanical residential properties, easy production, as well as inexpensive. Nevertheless, the research mostly focuses on the 946nm, 1064nm, and also 1319nm wavelength lasers, and also the 1123nm laser discharge is also a vital change.
Nd: YAG crystals have superior spooky as well as laser properties. It is just one of the most widely made used laser crystals. Compared to With Nd YVO4 crystal, the previous has high thermal conductivity, great mechanical properties, as well as simple development, and Nd: YAG crystal can be used directly; Cr YAG Q modulation to acquire peak power and also high repeating regularity result. However, since the doping concentration of Nd: YAG crystal is reduced and the absorption coefficient is small, it is difficult to realize the miniaturization of the laser and enhance its effectiveness. We have actually now acquired large, highly doped Nd: YAG crystals making use of the cozy ladder technique, with the mole portion of Nd ions doped up to 2.3.
2. Growth method
(1) Lifting method
Tira technique: Czochralsik: CZ technique, a crystal growth method established by Czochralsik in 1917 Fundamental concept: Under an affordable temperature field, the reduced end of the seed crystal installed on the seed crystal pole is decreased right into the raw product of the melt. Under the activity of the rotary electric motor and training device, the seed crystal rod rotates while gradually drawing upwards. After a number of technical phases, such as neck diminishing, shoulder expansion, shoulder rotation, equivalent diameter, completing, and pulling off, the single crystal with qualified geometric shape as well as the internal top quality is grown.
1) Advantages of the pulling method:
(a) During the growth process, it is convenient to observe the growth of the crystal
(b) The growth of the crystal on a free surface of the melt without contact with the crucible considerably decreases the stress on the crystal and avoids nucleation on the crucible wall surface
(c) It is easy to use orientated seed crystals as well as the “necking” process to get total seed crystals and also crystals of the wanted orientation. The great benefit of the pull-up method is the ability to grow crystals of higher quality at a faster rate
2) Disadvantages
(a) Possible contamination of the crystal by crucible material;
(b) The melt’s flow action, the transmission’s vibration, and the temperature level change all influence the crystal’s top quality.
(2) Bridgman technique
The Bridgman procedure is a typical thaw growth technique, generally divided right into upright and straight Bridgman process 2.
The vertical Bridgman procedure, likewise referred to as the crucible descent method, is a technique of growing crystals from melt. Typically, when the crucible is reduced in a crystallizing heating system and passes through an area with a large temperature level gradient, the melt takes shape in the crucible from the bottom up right into a single crystal. The crystallization heating system increasing along the crucible can also complete this procedure.
(3) Guided temperature level gradient technique
The guided temperature ladder technique is a single-formation approach to melt generated by related seed crystals. The temperature level area of TGT is primarily changed by readjusting the form as well as placement of the graphite home heating body, Mo insulation display, Mo crucible, the power of the heating body, and also the flow of distributing cooling water to develop an ideal temperature level gradient from the bottom to top
3. Main application of Nd YAG laser
The Nd: YAG laser has a wavelength of 1064 nm and is not near the absorption height of oxygenated hemoglobin, which has poor Nd: YAG laser absorption. However, its infiltration depth can get to about 8 mm, to ensure that it can play a therapeutic function in the much deeper part of the hemangioma. According to the different power outcome modes, Nd: YAG laser can be split right into continuous and also pulse kind 2. Continual Nd: YAG lasers are frequently utilized but are non-selective in thermal tissue damages.
Continual Nd: YAG laser is commonly used in the ent division, gynecology as well as surgical treatment. As well in dermatology, due to the “not good cosmetic result”, use is much more cautious. Compared with continuous Nd: YAG laser, pulsed Nd: YAG laser is much more constant with selective photothermal theory. It can lower heat damage to the surrounding typical cells as well as decrease the occurrence of scars as well as various other unfavorable reactions.
