What is Frequency Resolution of an Inteferometer?

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- GoPhotonics

Oct 25, 2023

The frequency resolution of an interferometer refers to its ability to distinguish two closely spaced frequencies in the input signal. In other words, it quantifies the accuracy with which the interferometer can resolve frequency differences.

The frequency resolution of an interferometer depends on several factors:

Baseline Length: In interferometry, the baseline refers to the distance between the two antennas or mirrors that are used to create interference. A longer baseline provides better frequency resolution because it results in greater phase differences for different frequencies.

Wavelength: The wavelength of the waves being observed is inversely proportional to the frequency. Longer wavelengths result in lower frequencies. The longer the wavelength, the finer the frequency resolution.

Aperture Size: The size of the antennas or mirrors used in the interferometer also affects the frequency resolution. Larger apertures can capture more information about the incoming waves, leading to better frequency resolution.

Sampling Time: The duration of time over which the interferometer collects data also affects frequency resolution. Longer observation times allow for more accurate determination of frequency differences.

The frequency resolution Δf of an interferometer can be calculated using the formula:


Δf is the frequency resolution, c is the speed of light, and L is the baseline length between the antennas or mirrors.