A composite cavity model for axisymmetric high Reynolds number separated flow II: Numerical analysis and results

In a companion paper (Wilmott and Fitt (1992)) a model was proposed for the separated high Reynolds number flow past a three-dimensional slender axisymmetric body. This composite model assumes that downstream of the body there is both a region of constant pressure and a Prandtl-Batchelor region. Matched asymptotic expansions were employed to recover a non-linear integro-differential equation for the shape of the separated region and some asymptotic solutions were obtained. The present study concerns the numerical solution of this equation and more detailed results concerning the cavity shape and closure properties.See also Journal of Engineering Mathematics 26: 539–555, 1992.     

Simultaneous daytime measurements of the atmospheric coherence diameter r(0) with three different methods

The most common parameter used in characterizing atmospheric turbulence (seeing) is the atmospheric coherence diameter, or r(0). r(0) can be measured in many ways. Three such techniques that are useful when one is making daytime seeing measurements by observing the Sun are described. Results from an experiment in which r(0) was measured with all three methods are presented.     

Photothermal measurements on optical thin films

An overview of the application of the photothermal technique for optical as well as thermophysical characterizations of thin films is given. The peculiarities of this technique are discussed in some detail, and selected important results are pointed out. Emphasis is placed on the influence of both residual absorption and randomly distributed inhomogeneities in thin films on their laser-damage resistance.     

Detection of probe dither motion in near-field scanning optical microscopy

The probe-to-sample separation in near-field scanning optical microscopes can be regulated by a noncontact shear-force sensing technique. The technique requires the measurement of a minute dither motion applied to the probe. We have characterized an optical detection method for measuring this motion to determine the optimum detection configuration in terms of sensitivity and stability. A scalar diffraction model of the detection method is developed for calculating sensitivity, and experimental results are found to be in good agreement with the theoretical predictions. We find that maximum sensitivity and stability cannot be achieved simultaneously, and it may be desirable in practice to trade sensitivity for enhanced stability.