FEMTOSECOND LASERS

Abstract

Femtosecond laser which belong to the category of ultrafast lasers or ultra-short pulse lasers emit optical pulseswith duration much below 1ps of the order of 10-15 sec. Mode locking lasers are used to produce such ultrashort pulses. Originated in 1963 when first laser was produced, now we have various kind of lasers with applicationinvaried areas like material processing, imaging and spectroscopy, biomedical etc. The field of femtosecond laser hasachieved significant advancement in interaction of laser with matter and material processing. The extreme short pulse wave can achieve very high intensity. Lasers have a wide application in industrial material processing. Thephrase “laser micromachining” has been used to describe laser machining applications where feature sizes onthemicrometer or tens of micrometers scale are achieved. Avalanche Ionization and Multiphoton Ionization arethetwo types of the non-linear processes. The problems in micromachining of difficult to machine materials (ceramics, silica etc.), graphitization in case of diamond, issue of melting in case of bulk materials are overcome byusingfemtosecond laser. It has applications in bio-medical field also. Femtosecond laser technology has recentlybeendeveloped for using in cataract surgery. LASIK surgery is performed to reshape the eye’s cornea for correctionof myopia, hyperopia and astigmatism. As the technology is recent, still there is no proper nomenclaturefor femtosecond laser assisted cataract surgery (ReLACS, FLACS, FALCS, TLACS). Using FSLs, we can buildacamera that is capable of recording at around a trillion fps. Potential applications include search andrescueplanning in hazardous conditions, collision avoidance for cars, and robots in industrial environments. Transient imaging also has significant potential benefits in medical imaging that could allow endoscopes to viewaroundobstacles inside the human body.