Rayleigh interferometer

This instrument is used to measure the difference in refractive index or in optical path length between two liquids by a null method. The measurement is converted into a difference in composition by means of a calibration curve. The use of the instrument is restricted to systems with a small difference in refractive index, otherwise a large number of standard mixtures have to be made up for calibration purposes. 

Bartell and Sloan [48] and Ewing and Rhoda [49] have made successful use of the interferometer in measuring the change in concentration due to adsorption from non-aqueous solutions. Further details of the instrument are given by Candler [50]. 

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The modified Rayleigh interferometer [54] is based on the same principle. Half of the beam (ordinary or extraordinary) is passed through the planar-oriented nematic cell and the other half transverses to the empty part of the cell. When the two beams are mixed an interference pattern results, from which the refractive indices n and n can be determined separately. In particular, changes in the refractive indices can be measured with high accuracy, using this method. 

In the Talbot-Rayleigh interferometer developed by Warenghem et al. [55, 56], the planar-oriented nematic cell is inserted in the focal plane of an ordinary spectroscope that covers only half of the field of polychromatic light. In this way dark bands (Talbot bands) appear due to the interference between the upper and the lower part of the beam. The position of the bands is correlated with the phase retardation (and, therefore, with the refractive index) induced by the nematic layer. By means of a proper spectrum analysis, dispersion curves of n and can also be determined. 

Raman experiments, antiferroelectrics 667 randomly constrained nematics 189 Rapini-Popular terms 77 rational routes, hydrocarbon cores 705 Rayleigh interferometer 131 Rayleigh scattering 172 reagents, hydrocarbon cores 694 ff rectangular phases... 

The values of D in Table 1 were obtained by the classical techniques of a Stokes diffusion cell [5] or a Rayleigh interferometer [6]. Nuclear magnetic resonance (n.m.r.) and neutron scattering can also be used,... 

The Mach-Zehnder and Rayleigh interferometers are solid alternatives to the Gouy interferometer. Although they are difficult to construct and adjust, they give information that is simpler to interpret. In the Mach-Zehnder apparatus, shown in Fig. 5.6-4(c),... 

Figure 3.4-1 Optical diagram of a commercial Michelson interferometer for infrared and Raman spectroscopy (Bruker IFS 66 with Raman module FRA 106). CE control electronics, D1/D2 IR detectors, BS beamsplitter, MS mirror scanner, IP input port, S IR source, AC aperture changer, XI — X3 external beams, A aperture for Raman spectroscopy, D detector for Raman spectroscopy, FM Rayleigh filter module, SC sample compartment with illumination optics, L Nd.YAG laser, SP sample position.

In dispersive spectrometers, the Rayleigh radiation may produce stray radiation in the entire spectrum, the intensity of which may be higher than that of the Raman lines. Interferometers transform the Poisson distribution of the light quanta of the Rayleigh radiation into white noise, which overlays the entire Raman spectrum. Therefore, all types of spectrometers must have means to reduce the radiant power of the exciting radiation accompanying the Raman radiation. 

Michelson interferometers can be combined with Rayleigh line filters (or subtractive double monochromators) in order to prevent the consequences of the multiplex disadvantage (Secs. 3.1.6, 3.3.6 Fig. 3.4-1). 

The transmission factor of the entire instrument (including interferometer and Rayleigh filter) is estimated to be t = 0.1. Finally, the radiant power of the Raman line equals ... 

Auciujlions arc usuatty dominani. Under Ihesc condi-lioiis. Ihe widlh of the Rayleigh line is directly proportional to the translational diffusion cocflictcnt DpThe 1)1.S mcthtxl uses optical mixing techniques and correlation analvsis to obtain these diffusion coelTicients. The line widths (I H to I MH/) arc too small to be measured by conventional spectrometers and even interferometers. 

Fig. 4.5 Basic diagram of a FT-Raman spectrometer. S, sample NF, notch filter for rejecting non-lasing radiation from laser RF, Rayleigh filter for rejecting radiation at laser frequency Ap, aperture wheel A, analyser I, interferometer.

Technical preparation of, from its elements, Journal of the Society of Chemical Industry, 32 (1913), 134-138. For the Rayleigh gas interferometer see George Lunge, Technical Gas Analysis, revised and rewritten by H.R. Ambler (London Gurney and Jackson, 1934), pp. 198-199. 

If instead of the Rayleigh criterion the full width at half maximum (FWHM) criterium is considered, the angular resolution is AOjei = 1.02A./T) X/D. For an interferometer, two equal brightness sources will be resolved when the fringe contrast goes to zero at the longest baseline b, this is... 

Figure 2.9 shows the fringe pattern for a single telescope and an interferometer for a point source, where the baseline separation isb = 5D. It can be observed that the resolution of the interferometer is 12 times higher than the resolution of the single aperture if the Rayleigh criterion is used. In interferometry, the resolution of the single aperture is the field of view of the interferometer. 

Fig. 5. Polarized Rayleigh-Brillouin spectrum of amorphous PnHMA taken with a Burleigh plane Fabry-Perot interferometer using a free spectral range of 12.4 GHz at 295 K. The two Brillouin peaks are shifted from the incident frequency by the product of the wave vector q and the sound velocity u. The line width of the Brillouin peaks is related to the attenuation of the sound waves. PnHMA.

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