• #19-4. The Composition, Principles, and Types of Lasers



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    Thermal damage time (TDT) refers to the time it takes for the heat in all the target tissues, including the main chromophores and the surrounding targets, to be reduced by 63% after the laser irradiation.


    Hair removal procedures generally use the TDT rather than TRT.


    The TDT in the hair follicles refers to the time required for the laser energy absorbed by the hairs to diffuse to the follicle associated hair stem cells.




    [Ad. ▶HYPERION(Nd:YAG) - Manufacturer: LASEROPTEK(www.laseroptek.com)

    HELIOSⅡ/LOTUSⅡ/HYPERION – Manufacturer: LASEROPTEK(https://www.laseroptek.com/)




    When laser is irradiated to the tissue, the photon energy is converted into heat, and the heat causes reversible and irreversible degeneration, coagulation, and vaporization of the tissue, which refers to the photothermal effect.


    When laser is irradiated with low photon energy, it does not generate heat in the tissue but stimulates to activate the cells within the tissue, degenerates the molecular structures, and destroys the cells by creating free radicals.


    This is called the photochemical effect.


    The photomechanical effect indicates changes in the shape of a substance when it is exposed to light by the physical force of the light energy.


    The most common mechanism of the photomechanical effect is light induced heating.


    The photothermal effect mentioned above can be included in the photomechanical effect.




    Physical precesses ocurring during laser radiation interaction with the tissue. Source : Helena Jelínková, Lasers for Medical Applications: Diagnostics, Therapy and Surgery, Woodhead Publishing, 2013.




    -To be continued


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