Interferometriaa

Interferometriaa is a family of measurement techniques that exploit the interference of waves to infer properties of light, sound, or other wave phenomena. By combining two or more wavefronts with a known phase relationship, interferometry translates small phase differences into measurable changes in light intensity or other signals.

The central idea is coherence and optical path difference. An interferometer splits a wave, delays one portion, and then recombines the beams. The resulting interference fringes depend on the phase difference, allowing precise determination of distances, surface shapes, or refractive indexes, often to fractions of a wavelength.

Common devices include optical interferometers such as the Michelson, Mach–Zehnder, and Fabry–Pérot configurations; radio and optical interferometers used in astronomy and metrology; and interferometric arrays for aperture synthesis in radio astronomy.

Applications span astronomy (measuring stellar diameters, imaging surfaces, and very-long-baseline interferometry for distant objects), metrology and surface profilometry, fiber-optic sensing, and gravitational-wave detection, where laser interferometers monitor tiny arm-length changes.

Historically, interference experiments began in the 19th century with Young and Fizeau; the Michelson interferometer became a standard tool in physics in the late 19th and early 20th centuries, and radio interferometry expanded in the mid–20th century, culminating in VLBI and modern gravitational-wave observatories.

Limitations include the need for coherent, stable waves, environmental isolation from vibrations and temperature fluctuations, precise calibration, and sophisticated data analysis to extract phase information.

See also coherence, phase, fringe, and aperture synthesis.