Phase-shift interferometry

Fundamentals. A beam of monochromatic light is polarized and split into two beams. One beam passes an optical medium, e.g. the electrolyte solution in an electrochemical cell close to the solution/electrode interface. After passage it interferes with the other beam for a review of two-beam interferometry see [915, 916]. This technique was limited both with respect to spatial resolution and sensitivity for further details, see [917]. Temporal or spatial modulation of the reference beam enabled the use of very thin cells (i.e. the sensitivity was increased) and the two-dimensional reconstruction of concentration maps. 

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Satoh, H., Nishimura, Y., Tsukamoto, K., Ueda, A., Kato, K., Ueta, S. 2007b. In-situ measurement of dissolution of anorthite in Na-CI-OH solutions at 22° using phase-shift interferometry. American Mineralogist, 92, 503-509. 

K. Onuma.T. Kameyama, and K. Tsukamoto, In situ study of surface phenomena by real time phase shift interferometry,/. Crystal Growth, 137,1994, 610-22... 

Su, Y.-D., Chen, S.-J., Yeh, T.-L. (2005) Common-path phase-shift interferometry surface plasmon resonance imaging system. Optics Letter 30 ... 

Figure 8 Effects of mixing ethanol and CO2 observed by means of phase shift interferometry at 7 = 323.1 K and P = 20 MPa. (a) Time-averaged radial distribution of ethanol concentration in a nozzle with a large orifice (0.75 mm), equal to the diameter of the mixing chamber in Figure 7. Gray background corresponds to a well-mixed fluid, whereas dark or light deviations corresponds to C02-rich and ethanol-rich parts of the stream, (b) Temperature shift in the jet caused entirely by the enthalpy of the mixing effect and shown as a function of the ethanol mole fraction.

Astrakharchik-Farrimond E, Shekunov BY, York P, Sawyer NBE, Morgan SP, Somekh MG, See CW. Dynamic measurements in supercritical flow using instantaneous phase-shift interferometry. Exp Fluids 2002 33 307-314. 

Figure Al.6.8. Wavepacket interferometry. The interference contribution to the exeited-state fluoreseenee of I2 as a fiinotion of the time delay between a pair of ultrashort pulses. The interferenee eontribution is isolated by heterodyne deteetion. Note that the stnieture in the interferogram oeeurs only at multiples of 300 fs, the exeited-state vibrational period of f. it is only at these times that the wavepaeket promoted by the first pulse is baek in the Franek-Condon region. For a phase shift of 0 between the pulses the returning wavepaeket and the newly promoted wavepaeket are in phase, leading to eonstnietive interferenee (upper traee), while for a phase shift of n the two wavepaekets are out of phase, and interfere destnietively (lower traee). Reprinted from Seherer N F et 0/1991 J. Chem. Phys. 95 1487.

The amplitude and phase of Xr are plotted in Figure 9.6a, whereas in Figure 9.6b the same function is depicted in terms of real and imaginary parts. It is clear from Figure 9.6a that the phase of the material s resonant oscillatory response undergoes a r phase shift relative to the nonresonant response in the vicinity of the spectral resonance. This is a direct manifestation of the retardation observed when driving the oscillators near their Raman resonances. In nonlinear interferometry, the Xr and... 

In this paper, we propose an experiment to test neutrality of isolated lithium atoms. Atom interferometry has been shown to be the ideal technique to measure weak interactions of an atom with its environment [1,2]. In particular, in 1991, Kasevich and Chu have mentionned the test of neutrality of atoms as a possible utilisation of their atomic interferometer [2], As far as we know, no further details have been published. The experimental set-up we propose is based on a Mach-Zehnder atom interferometer like the ones developped by the research groups of D. Pritchard [3], Siu Au Lee [4], A. Zeilinger [5] and the one under construction in our group [6]. If the same uniform electric field E is applied on both arms of the interferometer, a phase shift of the interferometric signal will appear. This phase shift will be proportional to the residual charge of lithium atom and to the electric field E. 

The main point to be made here is that the phase shift data obtained from spectral interferometry has two contributions surface motion and optical effects. These two contributions to the phase versus time data can be separated by performing these experiments at two angles of incidence and two polarizations, at technique we term ultrafast d3mamic ellipsometry. The optical effects during shock breakout in nickel films were hidden because they produce phase shifts of the same sign as that caused by surface motion. Ultrafast dynamic ellipsometry allowed that contribution to be measured [71]. In our experiments on bare metals, the observed optical effects are due to changes in the material s complex conductivity under shock loading. We will see below that this is only one of several kinds of optical effects that can be observed in these and other materials. 

In electron interferometry, there are often cases where great precision is required, for example, to measure the thickness distribution in atomic dimensions or to observe microscopic electromagnetic fields. To achieve such precision, phase amplification techniques peculiar to holography have been developed and used. Using these techniques, phase shifts as small as 1/100 of the wavelength can be detected [2.5]. 

Things are not quite as simple as they seem. In order for the constructive interference, which is at the core of wavepacket interferometry, to occur, not only must (t + At) = (t), but also the phases of apump and aprobe> which depend on the optical phase of the femtosecond laser rather than the molecular phase, must match. A rigorous treatment of the phase coherent pump/probe scheme using optically phase-locked pulse pairs is presented by Scherer, et al., [1990, 1991, 1992] and refined by Albrecht, et al., (1999), who discuss the distinction between and consequences of pulse envelope delays vs. carrier wave phase shifts (see Fig. 9.6). A simplified treatment, valid only for weak optical pulses is presented here. 

The total number of fringes, or cycles of phase shift, spanned by the disk of a planet with diameter D and a distance R from the radar is approximately ( )// )( projA), where proj is the projection of the interferometer baseline normal to the mean line of sight. For example, Arecibo interferometry linked the main antenna to a 30.5-m antenna about 11 km farther north. It placed about seven fringes on Venus, quite adequate for separation of the north-south ambiguity. The Goldstone main antenna (see Fig. 3) has... 

The crystal interferometer is a very delicate device air flow around the interferometer causes a serious drift of interference fringes. However, this method can detea the phase shift directly, and the resultant image quality exceeded expeaations, even of radiologists. While X-ray phase imaging was implemented by this two-beam X-ray interferometry for the first time, this approach is still the most sensitive of the X-ray phase imaging techniques. 

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