Dinterférométrie

Dinterférométrie is a term used in optics and metrology to describe a family of interferometric techniques that measure differential phase or optical path differences between two signals, beams, or regions of a specimen. In practice, the term is often used synonymously with differential interferometry or dual-path interferometry, emphasizing the differential nature of the measurement rather than an absolute path change.

Principles: The measurement relies on two optical paths that image or sample the quantity of interest while exposure to common-mode disturbances—such as vibrations, laser drift, or ambient temperature fluctuations—is minimized by taking a differential signal. The phase difference between the two arms, Δφ, is retrieved from the interferometric fringes using methods such as phase-shifting, heterodyne detection, or Fourier-transform analysis. The technique is particularly powerful for detecting very small phase changes while rejecting noise that is common to both paths.

Implementation: Dinterférométrie can be realized in common interferometer geometries such as dual-arm Mach-Zehnder or Michelson setups, and in fiber-optic sensor networks with two sensing channels. Differential detection may involve two photodetectors or a balanced receiver, and several variants employ digital processing or holographic reconstruction to extract phase information.

Applications: It finds use in metrology, structural health monitoring, vibration and strain sensing, and remote or distributed sensing networks. In geodesy and surface deformation studies, differential phase mapping enables precise measurements of subtle changes over time, while in industrial metrology it supports high-precision length and displacement measurements.

Advantages and limitations: The differential approach enhances sensitivity to differential changes and suppresses common noise but requires careful alignment, calibration, and management of differential systematic errors such as dispersion or polarization effects.