Thermal reaction in laser
According to the biological characteristics of different tissues, select the appropriate wavelength, energy, and pulse width to ensure effective treatment of the diseased tissue while avoiding damage to the surrounding normal tissue as much as possible. Selective photothermal effect includes three basic conditions: the wavelength can be preferentially absorbed by the target (the target tissue must absorb light at least 10 times higher than the surrounding tissue); the pulse width must be less than or equal to the target TRT, so that the target tissue does not have enough time The heat is transferred to the surrounding normal tissues, and the thermal damage to the surrounding normal tissues is minimal; suitable energy that can destroy the target without causing complications.
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Laser irradiation of different power densities on the target body will cause different thermal effects such as heating, melting, sublimation and ionization, as well as thermal stress and thermal shock isostatic and dynamic effects. Generally speaking, lower power density (104 W /cm2) the laser will cause local heating, thermal stress and melting of the target material and other thermal effects and thermal coupling effects; under the laser irradiation of medium power density (104∼107 W/cm2), the target material will melt, ablate, gas The phase transition behavior and induced mechanical effects are the main factors; the blue laser pointer power density above 107 W/cm2 will induce the target to generate plasma and cause high-amplitude shock waves.
2021-10-15 08:36:44
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