Nd: YAG, totally called neodymium-doped yttrium aluminum garnet crystal (Nd: Y3Al5O12), yttrium aluminum garnet crystal as its activator, the material of Nd atoms in the crystal is 0.6 ~ 1.1%, comes from the solid laser, can excite pulse laser or constant laser, giving off laser infrared wavelength 1.064 μm.
Short pulse Nd YAG laser has crucial applications in laser handling, photoelectric countermeasures, laser ranging, laser interaction, etc. Particularly the peak power laser acquired by Q switching is the core tool in several innovative scientific research studies and contemporary clinical tools and tools.
Neodymium-doped yttrium aluminum garnet (Nd: YAG) laser crystal has the advantages of excellent optical harmony, mechanical properties, high physical and chemical security, great thermal conductivity, and more.
It has become the main assistance product for the armed forces’ powerful laser technology and the application instructions of the medium and high-power lasers. It is among the “3 basic laser crystal products” widely used in the commercial, medical, army, and scientific research studies.
Nd: YAG crystal is still one of the most widely used solid laser tools because of its superb optical and mechanical homes, easy production, and low cost. However, the research mainly focuses on the 946nm, 1064nm, and 1319nm wavelength lasers and 1123nm laser discharge, which is also an important transition.
Nd: YAG crystals have superior spectral as well as laser properties. It is among the most commonly utilized laser crystals. Compared with Nd YVO4 crystal, the former has high thermal conductivity, good mechanical properties, and easy growth. Nd: YAG crystal can be utilized directly; Cr YAG Q modulation to obtain peak power and high repeating regularity output.
However, because the doping focus of Nd: YAG crystal is reduced and the absorption coefficient is little, it isn’t easy to recognize the miniaturization of the laser and boost its performance. Using the cozy ladder method, we have now acquired huge, highly drugged Nd: YAG crystals, with the mole fraction of Nd ions doped up to 2.3.
(1) Lifting method
Tira method: Czochralsik: CZ method, a crystal growth method established by Czochralsik in 1917.
Standard principle: Under a practical temperature level area, the lower end of the seed crystal installed on the seed crystal pole is decreased right into the raw material of the thaw. Under the action of the rotary motor and also the lifting device, the seed crystal rod revolves while gradually drawing upward.
After several technical phases, such as neck diminishing, shoulder development, shoulder turning, equivalent diameter, finishing, and managing, the single crystal with qualified geometric shape and top interior quality is grown.
1) Advantages of the drawing method:
(a) During the growth process, observing the crystal’s growth is convenient.
(b) The crystal’s growth on a free surface area of the melt without contact with the crucible considerably reduces the anxiety on the crystal. It protects against nucleation on the crucible wall surface.
(c) It is easy to use orientated seed crystals and the “necking” process to obtain complete seed crystals and crystals of the preferred positioning. The excellent advantage of the pull-up technique is the capacity to grow crystals better at a much faster rate.
(a) Possible contamination of the crystal by crucible product;
(b) The melt’s circulation action, the transmission’s vibration, and the temperature fluctuation all impact the crystal’s top quality.
(2) Bridgman method
The Bridgman procedure is a typical melt growth method, normally split into vertical and straight Bridgman procedures 2.
The vertical Bridgman procedure, called the crucible descent technique, expands crystals from the thaw. Generally, when the crucible is lowered in a crystallizing heating system and goes through an area with a huge temperature gradient, the melt takes shape in the crucible from an all-time low up into a single crystal. The crystallization furnace increasing along the crucible can also finish this procedure.
(3) Guided temperature gradient method
The directed temperature level ladder technique is a solitary formation approach of thaw generated by orientated seed crystals. The temperature field of TGT is primarily readjusted by adjusting the shape and position of the graphite heating body, Mo insulation screen, Mo crucible, the power of the heating body, as well as the flow of flowing cooling water to develop an ideal temperature level gradient 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 optimal of oxygenated hemoglobin, which has inadequate Nd: YAG laser absorption. Nevertheless, its infiltration depth can reach about 8 mm to ensure it can play a therapeutic function in the much deeper part of the hemangioma. According to the different energy output settings, Nd: YAG laser can be split right into continuous and pulse kind two.
Continuous Nd: YAG lasers are generally used but are non-selective in thermal tissue damage. Constant Nd: YAG laser is extensively used in the ent division, gynecology, and surgical treatment. As well as in dermatology, because of the “not good cosmetic impact,” usage is more cautious. Compared to continual Nd: YAG laser, pulsed Nd: YAG laser is more consistent with careful photothermal theory. It can lower warmth damage to the surrounding normal tissue and minimize the incidence of marks and various other negative reactions.