Patent ID: 7177029

Claim:
An interferometric stroboscopic method for topographically profiling a surface of a vibrating object, said method comprising the steps of: illuminating the vibrating object surface and a reference surface in an interferometer with a series of pulses of illumination to produce an interference pattern on a two-dimensional detector optically aligned with the object surface and having a plurality of pixels each corresponding to a respective location on the object surface; varying an optical path difference between the reference surface and the object surface to produce at each detector pixel an interferogram for a respective object surface location, each said interferogram being defined by a pixel-received variation in interference illumination intensity for the respective object surface location as the optical path difference is varied; transforming each said interferogram into the spatial frequency domain to define, for each said pixel, transformed interferogram data, wherein said transformed interferogram data for each said pixel represents relative intensity and interferometric phase of the interferogram received at said each pixel as a function of spatial frequency; calculating, for each said pixel, a height of the respective object surface location using said transformed interferogram data by determining the interferometric phase of the interferogram as a function of wavenumber using said transformed interferogram data; and creating a topographical profile of the object surface using the heights calculated in said prior step, said interferometric stroboscopic method being insensitive to changes in the wavelength of said pulses illuminating the vibrating object.