Coherence scanning interferometry with a focus-tunable lens

Coherence scanning interferometry is an established optical method that is able to measure the shape of objects with high precision. The surface of the object to be measured can be both optically smooth and optically rough. However, a major limitation of coherence scanning interferometry is that the object to be measured must mechanically move relative to the measuring device during the measurement procedure. We introduce an optical measurement method based on coherence scanning interferometry that is able to measure without the mechanical movement between the measured object and the measuring device. The suggested solution is that the reference plane moves. The imaging system includes an electrically focus-tunable lens. This lens ensures that the measured part of the object is sharply imaged during the measurement procedure. (C) 2019 Optical Society of America