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Mechanical Nanosensors
Published in Vinod Kumar Khanna, Nanosensors, 2021
Optical interferometry techniques (Krishnan et al. 2007), notably path-stabilized Michelson interferometry and Fabry-Perot interferometry, have been extended into the NEMS domain. The Michelson interferometer produces interference fringes by splitting a beam of monochromatic light into two paths so that one beam strikes a fixed mirror and the other a movable mirror; when the reflected beams are recombined, an interference pattern results. On the other hand, the Fabry-Perot interferometer uses multiple reflections between two closely spaced, partially silvered surfaces; part of the light is transmitted each time, reaching the second surface, and resulting in multiple offset beams which interfere with each other, producing an interference pattern with extremely high resolution, somewhat like the multiple slits of a diffraction grating increasing its resolution. In Fabry-Perot interferometry (Figure 4.17), the optical cavity formed within the sacrificial gap of the NEMS, between the NEMS surface and the substrate, varies the optical signal and directs it onto a photodiode (a semiconductor diode in which the reverse current varies with illumination) with the movement of the NEMS device in the out-of-plane direction. Optical displacement nanosensor. (Ekinci, K. L., Small, 1, 786, 2005.)
Interferometers
Published in Abdul Al-Azzawi, Photonics, 2017
Unlike the Michelson interferometer, which produces interference fringe patterns with two coherent beams of light, the Fabry–Pérot interferometer produces interference with a large number of coherent beams. Two optically-flat glass or quartz plates, each partially silvered on one face, are mounted in rigid frames. The fine screws enable the plates to be adjusted until their two silvered surfaces are precisely parallel. Light from an extended source S, passing through the interferometer, undergoes reflection back and forth, and the emerging parallel rays are brought together to interfere in the focal plane of a lens. The spacing, or thickness t, of the air layer between the two reflecting surfaces is an important performance parameter of the interferometer. When this spacing is fixed, the interferometer is often referred to as an etalon.
Analytical Test Methods for Polymer Characterization
Published in Nicholas P. Cheremisinoff, Elastomer Technology Handbook, 2020
Nicholas P. Cheremisinoff, Boyko Randi, Leidy Laura
In Fourier transform spectrometry, the wavelength components of light are not physically separated. Instead, the light is analyzed in the time frame of reference (the time domain) by passing it through a Michelson interferometer. The Michelson interferometer is so constructed that light is separated into two beams by a beamsplitter. One beam strikes a stationary mirror and is reflected back to the beamsplitter.
Measurement Uncertainty in Manufacturing Metrology: Uncertainty Analysis on the Measurement of Single-Fiber, PC Endface Fiber-Optic Connectors
Published in NCSLI Measure, 2018
Mario O. Valdez, Edward P. Morse, Charles G. Stroup
The instrument is a style of Michelson interferometer which forms interference fringes by dividing the illuminating light into two beams using a beamsplitter. One beam is reflected from the fiber-optic endface, while the other is bounces off the reference mirror. It is imperative that the reference mirror has minimal from error (flatness) to ensure that the beam reflects back along the same path to minimize its effect on possible retrace error, also caused by the imperfect geometry of the endface [10]. Accuracy of the endface geometry calculations are dependent on the quality of image generated by the instrument, hence the need for a very flat reference mirror.