Nd: YAG crystal, fully known as neodymium-doped yttrium aluminium garnet crystal (Nd: Y3Al5O12), yttrium aluminium garnet crystal as its activator, the material of Nd atoms in the crystal is 0.6 ~ 1.1%, comes from the solid laser, can delight pulse laser or continual laser, discharging laser infrared wavelength 1.064 μm.
Brief pulse Nd YAG laser has important applications in laser handling, photoelectric countermeasures, laser varying, laser interaction, and so on. Particularly the peak power laser acquired by Q switching is the core device in lots of sophisticated scientific studies and also modern-day scientific instruments and equipment.
Neodymium-doped yttrium aluminium garnet (Nd: YAG) laser crystal has the advantages of good optical uniformity, mechanical properties, high physical as well as chemical security, excellent thermal conductivity, and so on. It has actually come to be the major support product for army solid laser modern technology and also the application instructions of tools and also high-power lasers. It is referred to as among the “3 basic laser crystal products”, which are commonly utilized in industrial, medical, and armed forces, as well as scientific research studies.
Nd: YAG crystal is still the most commonly used solid laser medium as a result of its outstanding optical as well as mechanical buildings, easy manufacturing, and low cost. Nevertheless, the study mostly concentrates on the 946nm, 1064nm, and 1319nm wavelength lasers, as well as the 1123nm laser discharge is additionally an essential change.
Nd: YAG crystals have superior spooky as well as laser properties. It is among one the most extensively used laser crystals. Compared with Nd YVO4 Crystal, the previous has high thermal conductivity, excellent mechanical properties, as well as easy growth, as well as Nd: YAG crystal can be made use of straight; Cr YAG Q modulation to get peak power and high repetition frequency result.
However, since the doping concentration of Nd: YAG crystal is reduced as well as the absorption coefficient is small, it is tough to understand the miniaturization of the laser as well as boost its effectiveness. We have currently acquired big, highly doped Nd: YAG crystals utilizing the warm ladder method, with the mole fraction of Nd ions doped up to 2.3.
2. Growth method
(1) Lifting method
Tira technique: Czochralsik: CZ method, a crystal growth method established by Czochralsik in 1917
Standard principle: Under an affordable temperature field, the reduced end of the seed crystal mounted on the seed crystal rod is decreased into the raw product of the thaw. Under the activity of the rotary motor and training system, the seed crystal rod turns while slowly pulling up. After several technical phases, such as neck diminishing, shoulder growth, shoulder rotation, equal size, finishing, and pulling off, the single crystal with a qualified geometric shape and inner high 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 thaw without contact with the crucible considerably decreases the anxiety on the crystal and also stops nucleation on the crucible wall surface
( c) It is easy to use orientated seed crystals as well as the “necking” process to acquire complete seed crystals as well as crystals of the preferred positioning. The fantastic benefit of the pull-up approach is the capability to grow crystals of higher quality at a faster rate
(a) Possible contamination of the crystal by crucible material;
(b) The melt’s circulation action, the transmission’s vibration, and also temperature fluctuation all impact the crystal’s quality.
(2) Bridgman method
Bridgman process is a common thaw growth method, generally divided right into vertical as well as straight Bridgman procedure two.
The vertical Bridgman process, also known as the crucible descent method, is a technique of expanding crystals from the thaw. Usually, when the crucible is decreased in a crystallizing furnace and travels through a region with a huge temperature level gradient, the thaw takes shape in the crucible from an all-time low up right into a single crystal. The formation heating system rising along the crucible can additionally finish this procedure.
(3) Guided temperature gradient technique
The guided temperature ladder method is a solitary crystallization method of thaw generated by related seed crystals. The temperature level field of TGT is primarily adjusted by adjusting the form and position of the graphite heating body, Mo insulation display, Mo crucible, the power of the heating body, and also the circulation of circulating cooling water to develop an appropriate temperature level slope from the bottom to top
3. Main application of Nd YAG laser
The Nd: YAG laser has a wavelength of 1064 nm and also is not near the absorption peak of oxygenated haemoglobin, which has bad Nd: YAG laser absorption. Nevertheless, its penetration depth can get to about 8 mm, so it can play a restorative role in the much deeper part of the hemangioma.
According to the different power outcome settings, Nd: YAG laser can be divided right into constant and also pulse type 2. Continuous Nd: YAG lasers are typically made use of however are non-selective in thermal tissue damage. Continual Nd: YAG laser is commonly used in the ent department, gynaecology and also surgical treatment. And in dermatology, due to the “not good aesthetic result”, usage is a lot more careful. Compared with continual Nd: YAG laser, pulsed Nd: YAG laser is a lot more regular with the discerning photothermal concept. It can reduce heat damage to the bordering regular cells and also reduce the event of marks as well as various other adverse reactions.