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Figure 1. The light path through a Michelson interferometer.The two light rays with a common source combine at the half-silvered mirror to reach the detector. They may either interfere constructively (strengthening in intensity) if their light waves arrive in phase, or interfere destructively (weakening in intensity) if they arrive out of phase, depending on the exact distances between the ...
All interferometry prior to the invention of the laser was done using such sources and had a wide range of successful applications. A laser beam generally approximates much more closely to a monochromatic source, and thus it is much more straightforward to generate interference fringes using a laser. The ease with which interference fringes can ...
Aperture masking interferometry (or Sparse aperture masking) is a form of speckle interferometry, that allows diffraction limited imaging from ground-based telescopes (like the Keck Telescope and the Very Large Telescope), and is a high contrast imaging mode on the James Webb Space Telescope.
A simple two-element optical interferometer. Light from two small telescopes (shown as lenses) is combined using beam splitters at detectors 1, 2, 3 and 4.The elements create a 1/4 wave delay in the light, allowing the phase and amplitude of the interference visibility to be measured, thus giving information about the shape of the light source.
Very-long-baseline interferometry (VLBI) is a type of astronomical interferometry used in radio astronomy. In VLBI a signal from an astronomical radio source, such as a quasar, is collected at multiple radio telescopes on Earth or in space. The distance between the radio telescopes is then calculated using the time difference between the ...
Since its introduction, vibrometry by holographic interferometry has become commonplace. Powell and Stetson have shown that the fringes of the time-averaged hologram of a vibrating object correspond to the zeros of the Bessel function (), where (,) is the modulation depth of the phase modulation of the optical field at , on the object. [1]
The first interferometry experiment aimed at observing the correlation of angular velocity and phase-shift was performed by the French scientist Georges Sagnac in 1913. Its purpose was to detect "the effect of the relative motion of the ether". [1] [2] Sagnac believed that his results constituted proof of the existence of a stationary aether ...
Grating-Coupled Interferometry schematics. GCI is based on phase-shifting waveguide interferometry.Light of the sensing arm of the interferometer is coupled into a monomode waveguide through a first grating, and undergoes a phase change until it reaches a second grating, depending on the local refractive index within the evanescent field (see image).