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 AmericaFull Article | PDF Article