The interaction of laser light with biological molecules, and the applications to biology and medicine. See Laser
Microirradiation is a useful technique for the study of cell function by alteration of a specific organelle or part of a cell. The laser beam is focused through the objective of a microscope onto the cell. Practically speaking, it is easy to obtain spots of about 1 micrometer in diameter. Ruby, neodymium, and argon lasers are used for this purpose.
Laser spectroscopy is used to probe biological processes in which very fast reactions are involved or to study structural changes of complex molecules. The two techniques used are flash photolysis (in the nanosecond and picosecond range) and Raman spectroscopy.
Continuous-wave lasers have been employed as a “light knife,” that is as a surgical cutting and coagulation tool. Generally, CO2 lasers, emitting in the infrared, are used for this purpose. When the laser energy is focused onto a tissue surface, a small volume of tissue is heated, and thus only this area is “cut off.” An advantage of this procedure is that small capillaries are coagulated, preventing hemorrhage resulting from cut blood vessels. Argon lasers are the most commonly used for treating retinopathies, but also for glaucoma and cataract. Laser irradiation is used for removal of foreign pigments in the skin (tattoos), for treatment of vascular disorders (“wine marks”), and for removal of various pigmented skin lesions.