optical interferometer

An optical interferometer is a scientific instrument that measures tiny differences in light waves by combining (or "interfering") light paths from multiple sources or mirrors. When the light waves overlap, they create patterns of brightness and darkness called interference fringes. These patterns reveal extremely precise information about the distance, shape, or properties of objects, often at the scale of fractions of a wavelength of light. Interferometers are used in astronomy to observe distant stars, in physics to test fundamental theories, and in engineering for precise measurements, leveraging the wave nature of light to detect very subtle changes.