An excimer laser is a type of ultraviolet laser that emits short pulses of light in the ultraviolet spectrum. The term excimer is derived from excited dimer, reflecting the nature of the gain medium used in these lasers. Excimer lasers are widely used in various industrial, medical, and scientific applications due to their ability to deliver high-energy, UV light in short pulses.
Key features and characteristics of excimer lasers include:
Excimer molecules: The gain medium of an excimer laser consists of excited-state molecules called excimers, which are formed by combining reactive gases such as fluorine (F2), chlorine (Cl2), or xenon (Xe) with an inert gas like argon (Ar). The term excime" refers to the short-lived excited state formed by the combination of these molecules.
Ultraviolet emission: Excimer lasers primarily emit light in the ultraviolet range, typically in the deep ultraviolet (DUV) region. Common wavelengths include 193 nm (argon fluoride, ArF), 248 nm (krypton fluoride, KrF), and 308 nm (xenon chloride, XeCl). The short wavelength is advantageous for various applications, including precision material processing and medical procedures.
Pulsed operation: Excimer lasers operate in pulsed mode, emitting short-duration pulses of high-energy light. This pulsed nature is suitable for applications where precision and minimal heat generation are critical.
Materials processing: Excimer lasers are widely used for materials processing applications such as micromachining, semiconductor manufacturing (photolithography), and laser ablation. The short wavelength allows for precise material removal without excessive heat transfer to the surrounding area.
Medical applications: Excimer lasers are employed in various medical procedures, including refractive eye surgery (e.g., lasik), dermatology (skin ablation), and angioplasty (opening narrowed or blocked blood vessels). The ability to precisely remove tissue with minimal thermal damage makes them valuable in medical applications.
Gas discharge: Excimer lasers operate as gas discharge lasers, where an electrical discharge is used to excite the gas mixture, leading to the formation of the short-lived excimer molecules. The release of energy during the return to the ground state results in the laser emission.