Vibration insensitive single-shot interferometry using a wide-field laser microscope.

Here, we report measurements made with an external vibration-insensitive single-shot interferometer, which is applicable for on-machine measurement. Previously, we developed a simple single-shot interferometry method in which the optical intensities of interference fringes appear not as sinusoidal distributions but have a sawtooth-like distribution, and the peak distortion direction depicts the slope of the measured surfaces. These properties allow use of this method in vibration-insensitive interferometry. In this study, we have experimentally confirmed this concept through measurement of a quarter of a Si wafer specimen 50 mm in diameter. The vibration source was a motorized linear stage the surface of which fluctuated between ±400 nm in height. The obtained surface profiles of the Si wafer were consistent with measurements made with a commercial interferometer within 30 nm. • A novel vibration-resistant optical interferometry method was achieved. • Metal was deposited on one surface of a glass reference plate. • Optical intensity of interference fringe has a sawtooth-like distribution. • A single interferogram is sufficient for determination of surface inclination. • Measured profiles were coincident with target values within 30 nm. [ABSTRACT FROM AUTHOR]