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Electronic speckle pattern interferometry (ESPI), [1] also known as TV holography, is a technique that uses laser light, together with video detection, recording and processing, to visualise static and dynamic displacements of components with optically rough surfaces. The visualisation is in the form of fringes on the image, where each fringe ...
Alternatively, if a stable laser is available, the PDH technique can be used to stabilize and/or measure the instabilities in an optical cavity length. [3] The PDH technique responds to the frequency of laser emission independently of intensity, which is significant because many other methods that control laser frequency, such as a side-of ...
Linnik interferometer (microscopy) LUPI variant of Michelson; Lummer–Gehrcke interferometer; Mach–Zehnder interferometer; Martin–Puplett interferometer; Michelson interferometer; Mirau interferometer (also known as a Mirau objective) (microscopy) Moiré interferometer (see moiré pattern) Multi-beam interferometer ; Near-field interferometer
A vibrometer is generally a two beam laser interferometer that measures the frequency (or phase) difference between an internal reference beam and a test beam. The most common type of laser in an LDV is the helium–neon laser, although laser diodes, fiber lasers, and Nd:YAG lasers are also used.
A laser is divided into two beams by a beam splitter tilted by 45 degrees. The two beams propagate in the two perpendicular arms of the interferometer, are reflected by mirrors located at the end of the arms, and recombine on the beam splitter, generating interferences which are detected by a photodiode. An incoming gravitational wave changes ...
Set-up of a self-mixing interferometer with laser diode and monitor photodiode. Self-mixing or back-injection laser interferometry is an interferometric technique in which a part of the light reflected by a vibrating target is reflected into the laser cavity, causing a modulation both in amplitude and in frequency of the emitted optical beam.
Classification of the different kinds of optical autocorrelation. In optics, various autocorrelation functions can be experimentally realized. The field autocorrelation may be used to calculate the spectrum of a source of light, while the intensity autocorrelation and the interferometric autocorrelation are commonly used to estimate the duration of ultrashort pulses produced by modelocked lasers.
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]