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.
© 2005 Optical Society of America
(120.3180) Instrumentation, measurement, and metrology : Interferometry
(120.6650) Instrumentation, measurement, and metrology : Surface measurements, figure
(140.7090) Lasers and laser optics : Ultrafast lasers
Jeong Seok Oh and Seung-Woo Kim, "Femtosecond laser pulses for surface-profile metrology," Opt. Lett. 30, 2650-2652 (2005)