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Properties of
Laser Light

How Laser
Energy is Generated

Laser Tissue Interaction

Holmium Laser
in Endourology

Anatomy of a Laser Pulse

Understanding Energy Density

Safety Precautions

Ocular Hazards

Skin Hazards

Other Hazards

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Laser Tissue Interaction

Different types of lasers react differently with tissue. The wavelength of the laser is of primary importance. However the power density and exposure time also play a critical role in determining tissue interaction. Looking on the time axis (horizontal), there are 3 types of laser that are important in laser surgery: Q-switched, pulsed and continuous wave (CW). Laser such as Nd:YAG (1064 nm) come in all three types; each creates a very different tissue effects. A Q-switched Nd:YAG laser is used primarily for tattoo removal; a pulsed Nd:YAG laser (also referred to as long-pulsed) is used for general surgery where tissue coagulation is desired; a CW Nd:YAG laser is used in hair removal applications.

Here are some definitions of tissue interaction terms:

Electromechanical—causes dielectric breakdown in tissue caused by shock wave plasma expansion resulting in localized mechanical rupture.

Photoablative—causes photodissociation or breaking of the molecular bonds in tissue.

Photothermal—converts light energy into heat energy. This causes the tissue to heat up and vaporize.

Photochemical—causes target cells to start light-induced chemical reactions.