Chemical silver coating of fiber tips in near-field scanning optical microscopy.

We report what is believed to be the first experimental demonstration of silver coating by a wet chemical process on tapered fiber tips used in near-field scanning optical microscopy. The process occurs at room temperature and pressure and takes only a few minutes to complete. Many tips can be coated simultaneously.

Image power for size analysis in in-line Fraunhofer holography.

The role of total power contained within the reconstructed image in size analysis has been described. Using an aperture-limited hologram and a circular-cross-section opaque object as an example, we show that very accurate size analysis is possible by this mode of analysis.

Image formation in detuned interference-filter-aided in-line Fraunhofer holography.

Detuned interference filters as Fourier processors can be used to enhance the poor fringe contrast often encountered with in-line Fraunhofer holography of small or many far-fields-away micro-objects. The subsequent effect on the reconstructed-image irradiance distribution is described. The modified aperture-limited image shape and size, and the possible consequences on the quantitative analysis are discussed.

Dynamics of hologram recording in DuPont photopolymer.

Several dynamical aspects of the DuPont photopolymer film HRF-150-38 for holographic storage are described. We study temporal aspects of exposure, exposure time, processing situations, and storage effect. The quantities studied are diffraction efficiencies, thickness changes, and Bragg angle. The experimental results are performed with an argon-ion laser at 514.5 nm.

Algorithm for phase-difference measurement in phase-shifting interferometry.

A phase-shifting algorithm is proposed and experimentally demonstrated for phase-difference analysis. The method involves only three steps, the original and two equal in amount but unknown phase steps for each stage. Only six frames of data are thus sufficient for the phase-difference analysis between two stages. Real-time holographic interferometry with a concentration change in a sugar-water solution in a test cell is presented for experimental verification.

Removal of the diffraction halo effect in speckle photography by using a negative mask.

A method to neutralize the diffraction halo effect in speckle photography is presented. A negative of the halo is used in the fringe observation plane to achieve this goal. Experimental irradiance distributions as well as Young's fringes with and without the negative mask are presented. It is shown that the apodization procedure is effective in solving the problems caused by varying the diffraction halo irradiance.

Determination of refractive properties of fluids for dual-wavelength interferometry.

Methods to calculate the refractive properties of solutions at different wavelengths are described by using experimental data at just two wavelengths. The properties are the refractive index and its gradients with temperature and concentration. Cauchy's equation is used to determine the refractive indices. The gradients versus temperature and concentration are then determined by using the Murphy-Alpert and the Lorentz-Lorenz equation, respectively. Finally, the particular case of a triglycine sulfate aqueous solution is considered as an example. The approach should provide the desired information for fringe analysis when dual-wavelength holographic or other interferometry is used for solving heat and mass transfer problems in fluids during crystal-growth experiments.

Removing the diffraction halo effect in speckle photography of sinusoidal vibration.

Expressions to eliminate the diffraction halo effects in speckle photography of sinusoidal vibration are derived. Both maxima and minima positions in Young's fringes pattern tern are considereda, nd only the experimentalh alo intensity variation is assumed known.

Volume magnification in particle field holography.

An image-object volume relationship in holography for applications in quantitative particle fields is determined in terms of known physical parameters. The general relationships are described for collimated, point reference, or reconstruction sources. Some relevant methods for correlating the transverse magnification at different longitudinal distances are also described.

Simple approach to process speckle-photography data.

A simple approach to incorporate the effect of the variation in diffraction halo intensity on Young's fringes in speckle photography is described. Detailed solutions for the shifts in maxima and minima positions are presented for the case of double exposure.

Speckle photography of lateral sinusoidal vibrations: error due to varying halo intensity.

The effect of varying halo intensity in speckle photography of lateral sinusoidal vibration using Young's fringes is discussed. An interesting new result is found that, for nonunity contrast or visibility, the relative fringe shift (or the error) for minima is always minimum for the lower-order fringes. Also the error in the fringe maxima position is lowest generally at intermediate fringe orders. However, as the visibility reduces the trend becomes similar to that for the case of minima. For maxima and minima both, the error is less for larger amplitude vibrations and higher visibility.

Direct observation of laser speckles for real-time analysis of lateral motions.

A method for real-time observation of speckle movement for the analysis of lateral motions is suggested. The method involves significant magnification using lenses and a TV-camera monitor system. This approach has the advantages of conventional speckle photography without the need for any chemical processing.