Biological Laser Applications
All biological laser applications are based on the interaction of laser light with biological systems. Such interaction causes a broad spectrum of effects which can be divided into three groups.
First, low-intensity laser light is absorbed, reflected, or reradiated (as fluorescence) by the substance so that no changes occur within it. Such interactions form the basis for the laser diagnostics (spectral diagnostics of molecules and macro diagnostics on the tissue level).
Second, low-intensity UV and visible radiation can excite electronic states in molecules, and specific photobiological effects occur due to excitation of chromophores in cells (endogenous or exogenous). These processes occur from the light from incoherent sources as well, but the use of laser light can give several benefits from a practical point of view. This group of effects encompasses molecular photobiology and photomedicine.
The third class of effects involves high-intensity laser radiation which causes damage to tissues by thermal or hydrodynamical destruction. Such processes, rarely observed with incoherent light sources, form the basis for laser surgery.