High-speed stroboscopic imaging with frequency-doubled supercontinuum

Abstract

Scanning white-light interferometry (SWLI) is a high-resolution, non-contact imaging technique that can be used to characterize objects ranging from biological tissues, to novel materials and components. SWLI allows reconstructing 3D images from the recorded interference pattern created by a reference and an object reflecting light. SWLI is not restricted to measuring static samples, but rapidly oscillating objects can also be characterized with modulated light sources that illuminate the sample motion. In this case a camera captures at select phases of the motion which permits stroboscopic imaging of the “frozen sample”. Here, we demonstrate stroboscopic white-light interferometry using a specially designed supercontinuum source that can capture the 3D image of a MEMS oscillating at 2.16 MHz with sub-100 nm resolution which is orders of magnitude faster than earlier attempts. Our experimental setup should even be able to image objects oscillating at frequencies up to several tens MHz, which is on pair with the capability of current light sources employed for SWLI.