Surface Shape Measurement by Wavelength Scanning Interferometry Using an Electronically Tuned Ti:sapphire Laser

We developed a high speed and high resolution surface shape measurement system based on wavelength scanning interferometry with an electronically tuned Ti:sapphire laser. This laser emits pulses and the wavelength of each pulse can be tuned arbitrarily within 680 nm and 1056 nm. We also designed a high speed multiport CCD camera as a detector. This camera is synchronized with wavelength scanning of the laser at the frequency of 250 Hz. We could measure the object shape with a height resolution of 3.05 μm at the tuning range from 740.0 nm to 842.3 nm. By simple parabolic curve fitting to the Fourier peak of interference signals from each CCD pixel, the height resolution has been improved to the order of submicrometers.