Lasers interferometry experiments

Experiments are reported on the dissolution rate and permeation rate for thin (1 nm) PMMA films exposed to liquid MEK. The films contain ca. 1 % of covalently-bound Phe, a fluorescent dye. By monitoring the dissolution rate by laser interferometry and the fluorescence quenching of Phe by MEK, we can determine ... 

D. J. Tannor I would like to point out that the Scherer-Fleming wavepacket interferometry experiment is very different from the Tannor-Rice pump-dump scheme, in that it exploits optical phase coherence of the laser light (optical phase coherence translates into electronic phase coherence between the wavepackets on different potential surfaces). However, there was a paragraph in the first paper of Tannor and Rice [7. Chem. Phys. 83, 5013 (1985), paragraph above Eq. (11)] that did in fact discuss the role of optical phase and suggested the possibility of experiments of the type performed by Scherer and Fleming. 

The resolution obtainable in laser spectroscopy experiments is limited ultimately by the bandwidth of the multimode laser output. This is not usually important in laser-induced fluorescence or Raman scattering experiments. However, for Brillouin scattering, for saturated absorption, and for two-photon absorption experiments, single-frequency lasers are essential. These are also necessary in interferometry and holography whenever the optical path difference exceeds 30 cm. Many different schemes for obtaining singlefrequency output from lasers have been reported. We shall consider only a few of the most commonly used techniques. We assume throughout that the laser has been constrained to... 

Nonnal spontaneous Raman scahering suffers from lack of frequency precision and thus good spectral subtractions are not possible. Another limitation to this technique is that high resolution experiments are often difficult to perfomi [39]. These shortcomings have been circumvented by the development of Fourier transfomi (FT) Raman spectroscopy [40]. FT Raman spectroscopy employs a long wavelength laser to achieve viable interferometry. 

Another set of experiments that exploited the coherence of laser emission used interferometry or reffactometry to study a range of phenomena. These included polymerization kinetics (39), diffusion (40), surface tension (41), and viscosity (42). These experiments, along with the laser light scattering experiments, can be found in Table III. 

Table III. Laser Experiments Raman, Light Scattering and Interferometry...

In the experiments described here, two separate techniques have been used for interferometric characterization of the shocked material s motion frequency domain interferometry (FDI) [69, 80-81] and ultrafast 2-d spatial interferometric microscopy [82-83]. Frequency domain interferometry was used predominantly in our early experiments designed to measure free surface velocity rise times [70-71]. The present workhorse in the chemical reaction studies presented below is ultrafast interferometric microscopy [82], This method can be schematically represented as in Figure 6. A portion of the 800 nm compressed spectrally-modified pulse from the seeded, chirped pulse amplified Ti sapphire laser system (Spectra Physics) was used to perform interferometry. The remainder of this compressed pulse drives the optical parametric amplifier used to generate tunable fs infrared pulses (see below). 

The realization of Bose-Einstein condensation and the atom laser has opened up an opportunity to observe and use in experiments the coherent properties of atomic matter. Coherent atomic sources can be used for the purposes of atom interferometry and holography. A direct observation of interference in a BEC was made in an experiment by Andrews et al. (1997). A BEC cloud obtained from with 5 x 10 sodium atoms was cut by a blue-detuned laser beam into two parts. The two parts of the condensate were then released from the trap. In the course of their free expansion, the two parts of the BEC overlapped and produced an interference pattern, which was probed by absorption imaging. The interference fringes showed good contrast, thus pointing to the conservation of long-range order in the condensates. 

The development of high tech materials such as ceramics or high strength composites requires the application of new powerful tools of theoretical and experimental mechanics in combination with modern computational aids. The application of so-called hybride methods of solid mechanics has been one characteristic trend of development above all for high strength materials. The main points of this paper deal with the utilization of finite element method (PEM) and boundary element method (BEM) for evaluation of ceramic components and carbon fibre composites. Finally the authors intend to give a short survey of new results combining computer mechanics and experiments carried out by means of laser and speckle interferometry and the micro moire method. 

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