Introduction and principle of Nd YAG Laser

Laser or LASER in English, its full name is Light Amplification by Stimulated Emission of Radiation

Nd. YAG is its simplified English name, and yttrium aluminum garnet crystal is its activator. The content of Nd atoms in the bulk crystal is 0.6~1.1%. It is a solid laser, which can excite pulsed laser or continuous laser, and the emitted laser is an infrared wavelength of 1064nm.

Here is the content list:

l Introduction of Nd YGA Laser

l Generation principle of Nd YGA Laser

Introduction of Nd YGA Laser

The pump lamp used by Nd YAG activating material crystal is mainly a krypton or xenon lamp. The emission spectrum of the pump lamp is a broadband continuous spectrum, but only a few fixed spectral peaks are absorbed by Nd ions. Therefore, the pump lamp only uses a small part of the spectral energy, and most of the spectral energy that is not absorbed is converted into heat energy, so the energy utilization rate is low.

The spectral region of Nd: YAG absorption is 0.730 μ m ~ 0.760 μ M and 0.790 μ m ~ 0.820 μ m. After the spectral energy is absorbed, it will lead to the transition of atoms from low energy level to high energy level, and some atoms that transition to high energy level will transition to low energy level and release the same frequency monochromatic spectrum, but the released spectrum has no fixed direction and phase, so the laser cannot be formed yet.

Generation principle of Nd YGA Laser

When the active material is placed in two parallel mirrors (one of which reflects 100% and the other 50% transmission mirror), an optical resonator can be formed. In this optical resonator, the non-axially propagating monochromatic spectrum is discharged from the cavity: and the axially propagating monochromatic spectrum travels back and forth in the cavity.

When the monochromatic spectrum travels back and forth in the laser material, it is called "self-excited oscillation" in the resonant cavity. When the pump lamp provides enough high-energy atoms in the laser material, there are three processes spontaneous emission transition, stimulated emission transition, and stimulated absorption transition between the two levels of atoms with high-energy levels. The excited emission light generated by the stimulated emission transition has the same frequency and phase as the incident light. When the light repeatedly passes through the active material in the "particle number inversion state" in the resonant cavity, the intensity of the monochromatic spectrum at the same frequency is increased to generate a laser, and the laser with high permeability can be emitted through 50% of the transmission mirror in the resonant cavity, becoming a continuous laser.

The high peak power and short pulse duration deliver efficient destruction of the target chromophore such as tattoo ink, pigment, or collagen. The electro-optic(EO)Q-Switch, acting as a high-speed shutter, stores energy between pulses enabling the laser to peak power output of 200MW in 6ns pulse width. It forces energy at a high rate, and the target chromophores vibrate and shatter, without harming the surrounding skin on all skin.

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