Michelson interferometer INDEX

Tian, Z. Yam, S. S. Loock, H., Refractive index sensor based on an abrupt taper Michelson interferometer in a single mode fiber, Opt. Lett. 2008, 33, 1105 1107... 

The interferometric determination of the index of refraction consists of determining the increase in the number of wavelengths in the light path of a Michelson interferometer as the gas is admitted to a previonsly evacnated cell that is placed in one of the two mutually perpendicular beam arms of the interferometer. 

Due to the limited response time of suitable sensors fast sorption or gas transport processes on a time scale below a second are hard to monitor. To significantly improve the resolution in time an interferometric pressure sensor can be applied. The central part of the interferometric pressure sensor presented is a Michelson-interferometer this set-up is sensitive to changes in gas pressure as the index of refraction, and thus the optical path length for a laser beam within the interferometer, is a function of the gas density. 

High resolution gas pressure measurements based on the evaluation of the refractive index can be performed with a Michelson-interferometer ... 

Bruker IFS 114 are marked in Fig. 50. For the sample compartment (A 3), the reflection attachment (A 3a) is shown in Fig. 50 which can be inserted at one of the two foci. Characteristic and outstanding is the design of the Michelson interferometer in this instrument (A 2 in Fig. 50). The radiation emitted by the source is not collimated at first but focussed on the beam-splitter. The angle of incidence on the beam-splitter is rather small (nearly normal incidence). This is advant-tageous with respect to the polarization properties of the beam-splitter. We recall from Section 4.1 and Fig. 15 that the efficiency (4 RT) of thin film beamsplitters depends on its thickness, on its refractive index, on the wave number of the radiation, and, last but not least, on the polarization of the light. The latter dependence is rather drastic for angles of incidence near 45° which are close to... 

The second refractivity virial coefficient is usually small compared with the second density virial coefficient, and so estimates can be made for B . Details of the experimental method of refractive index measurement using a Michelson interferometer at temperatures from 250 K to 340 K and at pressures up to 3 MPa are given by Hausler and Kerl [88-hau/ker], who also derive values for third density virial coefficients from their results. 

Compliances 512 and s-a relate to contraction in the thickness (y) direction for stresses along the x and z axes, respectively. For sufficiently thick specimens the changes in thickness, claimed accurate to within 0.25 pm, can be measured by extensometers, fitted with lever arms, which bear against the faces of the polymer sheet. Thin cover slides are inserted between the extensometer elements and the specimen faces to remove any possibility of indentation [8]. For thinner specimens, or materials of high optical clarity, the sample can be inserted in one arm of a Michelson interferometer and immersed in turn in two fluids of different refractive index. The fringe shift Am can be related to the change in thickness At by... 

Analogous to the Michelson interferometer, the Mach-Zehnder interferometer is based on the two-beam interference by amplitude splitting of the incoming wave. The two waves travel along different paths with a path difference As = 2a cos O (Fig. 4.30b). Inserting a transparent object into one arm of the interferometer alters the optical path difference between the two beams. This results in a change of the interference pattern, which allows a very accurate determination of the refractive index of the sample and its local variation. The Mach-Zehnder interferometer may be regarded therefore as a sensitive refrac-tometer. 

U. Hohm, K. Kerl, A Michelson twin interferometer for precise measurements of refractive index of gases between 100 K and 1300 K. Meas. Sci. Technol. 1(4), 329-336 (1990)... 

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