Nd: YAG, fully referred to 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%. Belongs to the solid laser, can excite pulse laser or constant 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, etc. The peak power laser obtained by Q switching is the core gadget in many innovative scientific research studies and contemporary clinical tools and devices.
Neodymium-doped yttrium aluminium garnet (Nd: YAG) laser crystal has the advantages of good optical harmony, mechanical properties, high physical and chemical security, excellent thermal conductivity, and so forth. It has become the primary support material for military solid laser technology and the application instructions of tools and high-power lasers. It is referred to as one of the “3 basic laser crystal products”. Which is extensively used in industrial, clinical, armed forces, and clinical research.
(1) Advantages
Nd: YAG crystal is still the most commonly used strong laser tool due to its superb optical and mechanical, very easy production, and low cost. Nonetheless, the research study mainly concentrates on the 946nm, 1064nm, and 1319nm wavelength lasers, and the 1123nm laser discharge is likewise a crucial shift.
Nd: YAG crystals have superior spooky and laser properties. It is just one of the most extensively utilized laser crystals. Compared with Nd YVO4 crystal, the former has high thermal conductivity, great mechanical properties, and easy development. Nd: YAG crystal can be used directly; Cr YAG Q modulation to acquire peak power and high rep regularity result. However, because the doping focus of Nd: YAG crystal is reduced and the absorption coefficient is little. It is tough to understand the laser’s miniaturisation and boost its performance. We have acquired large, extremely drugged Nd: YAG crystals utilizing the cosy ladder method, with the mole fraction of Nd ions doped up to 2.3.
Growth method
(1) Lifting method
Tira method: Czochralsik: CZ method, a crystal growth method established by Czochralsik in 1917
Basic concept: Under a reasonable temperature area, the lower end of the seed crystal installed on the seed crystal pole is decreased into the raw product of the thaw. Under the action of the rotating motor and also the training mechanism, the seed crystal rod revolves while slowly pulling up. After several technical phases, such as neck diminishing, shoulder development, shoulder rotation, equal diameter, finishing, and carrying out, the solitary crystal with qualified geometric shape and inner high quality is expanded.
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 significantly reduces the stress on the crystal as well as protects against nucleation on the crucible wall
(c) It is easy to use orientated seed crystals and the “necking” procedure to get complete seed crystals and crystals of the preferred positioning. The excellent advantage of the pull-up approach is the ability to expand crystals of higher quality at a faster rate
2) Disadvantages
( a) Possible contamination of the crystal by crucible material;
(b) The melt’s circulation activity, the transmission’s resonance, and the temperature level fluctuation all affect the crystal’s high quality.
(2) Bridgman method
The Bridgman process is a typical thaw growth technique, usually separated right into vertical and straight Bridgman procedures 2.
The good Bridgman process, called the crucible descent technique, grows crystals from the thaw. Usually, when the crucible is reduced in a crystallizing heating system and passes through a region with a big temperature gradient, the melt takes shape in the crucible from an all-time low up right into a single crystal. The crystallization furnace climbing along the crucible can also complete this process.
(3) Guided temperature level slope technique
The guided temperature ladder method is a solitary condensation technique of thaw caused by orientated seed crystals. The temperature field of TGT is primarily changed by adjusting the shape and position of the graphite heating body, Mo insulation screen, Mo crucible, the power of the home heating body, and the circulation of circulating cooling water to develop an ideal temperature level slope from the bottom to top
The 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 haemoglobin. Which has poor Nd: YAG laser absorption. Nonetheless, its infiltration deepness can reach 8 mm. So that it can play a vital role in the much deeper part of the hemangioma.
According to the various power result modes, Nd: YAG laser can be divided into continual and pulse type two. Constant Nd: YAG lasers are typically utilized but are non-selective in thermal tissue damage. Constant Nd: YAG laser is commonly used in the ent division, gynaecology, and surgical procedure. As well as in dermatology, due to the “not good cosmetic effect”, usage is a lot more careful. Compared with continual Nd: YAG laser, pulsed Nd: YAG laser is much more regular with the selective photothermal concept. It can lower warmth damage to the surrounding normal cells and minimize the event of marks and other damaging responses.
