Colour moiré interferometry for physical sensing using a standard web camera

Digital moiré patterns are an effect seen in digital pictures when a high-contrast periodic object being imaged interferes with the periodic image detector in the camera. This is often an undesired effect, which is usually removed through various filtering processes. However in this work we demonstrate the ability to use a deliberately created moiré pattern to measure the physical distance of an object from a web camera with a resolution of 131 µm. This measurement principle is then adapted to measure weight as a ubiquitous scale with a resolution of 240 µg.