Excimer laser
Intrigued, they investigated further, finding that the laser made clean, precise cuts that would be ideal for delicate surgeries. Excimer laser light is typically absorbed within the first billionth of a meter (nanometer) of tissue. In 1980 - 1983, Dr.This resulted in a fundamental patent Excimer lasers are quite large and bulky devices, which is a disadvantage in their medical applications, although their size is rapidly decreasing with ongoing development. . Watson Research Center when they observed the effect of the ultraviolet excimer laser on biological materials.
This is because noble gases such as xenon and krypton are highly inert and do not usually form chemical compounds. Rangaswamy Srinivasan and Dr.
Rather than burning or cutting material, the excimer laser adds enough energy to disrupt the molecular bonds of the surface tissue, which effectively disintegrates into the air in a tightly controlled manner through ablation rather than burning. Thus excimer lasers have the useful property that they can remove exceptionally fine layers of surface material with almost no heating or change to the remainder of the material which is left intact.
An excimer laser (sometimes, and more correctly, called an exciplex laser) is a form of ultraviolet laser which is commonly used in eye surgery and semiconductor manufacturing. An excimer laser typically uses a combination of an inert gas (argon, krypton, or xenon) and a reactive gas (fluorine or chlorine).
The excited compound can give up its excess energy by undergoing spontaneous or stimulated emission, resulting in a strongly-repulsive ground state molecule which very quickly (on the order of a picosecond) disassociates back into two unbound atoms. Under the appropriate conditions of electrical stimulation, a pseudo-molecule called an excimer (or in case of noble gas halides, exciplex) is created, which can only exist in an energized state and can give rise to laser light in the ultraviolet range. The UV light from an excimer laser is well absorbed by biological matter and organic compounds.
This forms a population inversion between the two states. Most excimer lasers are of the noble gas halide type, for which the term excimer is strictly speaking a misnomer (since a dimer refers to a molecule of two identical or similar parts): The correct but less commonly used name for such is exciplex laser. The wavelength of an excimer laser depends on the molecules used, and is usually in the ultraviolet: Excimer lasers, such as XeF and KrF, can also be made tunable using a variety of prism and grating intracavity arrangements. Excimer lasers are usually operated with a pulse rate of around 100 Hz and a pulse duration of ~10 ns, although some operate as high as 8 kHz and 200 ns. For electric discharge pump see: Nitrogen laser. The high-power ultraviolet output of excimer lasers makes them useful for surgery (particularly eye surgery), for lithography for semiconductor manufacturing, and for dermatological treatment. However, when in an excited state (induced by an electrical discharge or high-energy electron beams, which produce high energy pulses), they can form temporarily-bound molecules with themselves (dimers) or with halogens (complexes) such as fluorine and chlorine.
James Wynne at IBM’s T. Samuel Blum was working with Dr.
J. These properties make excimer lasers well suited to precision micromachining organic material (including certain polymers and plastics), or delicate surgeries such as eye surgery LASIK. The first excimer laser was invented in 1970. Laser action in an excimer molecule occurs because it has a bound (associative) excited state, but a repulsive (disassociative) ground state.
The term excimer is short for excited dimer , while exciplex is short for excited complex .
