Digital holography: Evolution from a research topic to a versatile tool for the inline 100% 3D quality control in industry

Digital multiwavelength holography is a technique for precise 3D height measurements of optically rough surfaces. We demonstrate measurements on a milled surface, using four wavelengths between 514 and 532 nm, and achieve precision in the submicrometer range. Height structures of <400 nm can be resolved up to an unambiguous height of 370 mm and with a lateral resolution of 7 mm. Acquisition times of < 400 ms, including the time needed for parallel processing of the data, make our sensor a versatile tool for high-throughput 100% inspection in manufacturing environments.