Adaptive Optics & Interferometry: Physical Mechanisms

An adaptive-optics system uses a reference source, wavefront sensor, high-speed control computer, and deformable mirror. An interferometer combines light or radio signals from multiple telescopes with accurately known delays and baselines.

Adaptive optics measures wavefront errors many times per second and reshapes a mirror to apply the opposite distortion. Interferometry preserves phase information so signals from separated antennas or telescopes interfere coherently, encoding source structure at angular scales set by wavelength divided by baseline.

Corrected images show narrower point-spread functions and higher Strehl ratios than uncorrected images. Interferometers such as the Very Large Array and ALMA reconstruct images from many baseline measurements and achieve resolution far beyond one dish of comparable diameter.

Turbulent air introduces spatially varying optical path delays. Adaptive optics measures those errors many times per second and applies the opposite shape to a deformable mirror. Interferometry measures phase or correlated intensity differences between apertures; source structure changes fringe visibility as baseline and orientation change. The achievable angular resolution scales roughly with wavelength divided by baseline, but image fidelity requires many spatial-frequency samples.