optical path difference

Optical path difference (OPD) refers to the difference in distance that light waves travel when they follow different paths. This concept is important in fields like optics and interferometry. When light encounters obstacles or passes through different materials, it can take various paths to reach the same point. The OPD can affect how these light waves combine, potentially leading to interference patterns, such as bright and dark fringes. These patterns help scientists study light properties and behaviors in experiments, enhancing our understanding of wave phenomena in both natural and engineered systems.