title: Femtosecond laser pulses for surface-profile metrology.
abstract: We discuss two ways to use femtosecond pulsed lasers as a new interferometric light source for enhanced precision surface-profile metrology. First, a train of ultrafast laser pulses yields repeated low temporal coherence, which allows unequal-path scanning interferometry, which is not feasible with white light, to be performed. Second, the high spatial coherence of femtosecond pulsed lasers enables large-sized optics to be tested in nonsymmetric configurations with relatively small-sized reference surfaces. These two advantages are verified experimentally with Fizeau and Twyman-Green type scanning interferometers.
authors.affiliation: Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology, Science Town, Daejeon 305-701, South Korea.
authors.forename: Jeong Seok
authors.initials: JS
authors.lastname: Oh
authors.forename: Seung-Woo
authors.initials: SW
authors.lastname: Kim