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Source: PSI – KIT
Understanding Michelson Interferometers
A Michelson interferometer, invented by Albert Abraham Michelson in the late 19th century, is a commonly used device for measuring distances and in various other applications.
Interferometer Setup and Operation Principle
A Michelson interferometer typically uses a laser as a light source, although other light sources can also be used. It consists of a beam splitter, two interferometer arms with end mirrors, and a photodetector. The beams are aligned to maximize overlap at the detector.
There are different configurations of Michelson interferometers, such as using retroreflectors for better alignment sensitivity.
Output Signal
The interference signal at the detector depends on the phase difference between the beams from the two arms. Perfect alignment results in maximum interference contrast, while imperfect alignment reduces the contrast.
Non-Monochromatic Light
With non-monochromatic light sources, achieving perfect interference is challenging. The interference contrast decreases with increasing arm length difference, especially with broader bandwidth light sources.
Applications of Michelson Interferometers
- Distance Measurements: Used for precise length measurements, such as monitoring machine parts or detecting gravitational waves.
- Optical Coherence Tomography: Utilizes interference near zero arm length difference for imaging.
- Spectral Measurements: Wavelength determination and Fourier transform spectroscopy.
- Chromatic Dispersion Measurements: Measuring dispersion in optical elements.
- Tunable Optical Filters: Adjusting optical characteristics through arm length difference.
Factors Affecting Accuracy
Factors like stabilized light source wavelength, mechanical vibrations, and optical phase differences impact the accuracy of distance measurements using Michelson interferometers.
Similar Interferometers
Other variations of Michelson interferometers include Twyman–Green interferometers and fiber-based interferometers, each with unique characteristics and applications.
Michelson interferometers have a wide range of scientific and industrial applications, showcasing their versatility and importance in modern optics and photonics.
Source: Britannica
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