Physics | Open Access Articles | Digital Commons Network™

The Temporary Capture Of Light By A Dielectric Film, James A. Lock Oct 1985

The Temporary Capture Of Light By A Dielectric Film, James A. Lock

Physics Faculty Publications

When a wave packet of light passes through a dielectric film it is found that at a transmission maximum, the group velocity of the light wave packet within the film attains its minimum value. Similarly, at a transmission minimum, it is found that the group velocity of the light wave packet within the film attains its maximum value. The measurability of this effect is also discussed.

Go to article

Incident Beam Polarization For Laser Doppler Velocimetry Employing A Sapphire Cylindrical Window, James A. Lock, Harold J. Schock Jul 1985

Incident Beam Polarization For Laser Doppler Velocimetry Employing A Sapphire Cylindrical Window, James A. Lock, Harold J. Schock

Physics Faculty Publications

For laser Doppler velocimetry studies employing sapphire windows as optical access ports, the birefringency of sapphire produces an extra beam intersection volume which serves to effectively smear the acquired velocity flow field data. It is shown that for a cylindrical window geometry, the extra beam intersection volume may be eliminated with minimal decrease in the fringe visibility of the remaining intersection volume by suitably orienting the polarizations of the initial laser beams. For horizontally incident beams, these polarizations were measured at three intersection locations within the cylinder. It was found that the measured polarization angles agreed with the theoretical predictions.

Go to article

N-Color Spin Models In The Large N Limit, Mehran Kardar, Miron Kaufman Jun 1985

N-Color Spin Models In The Large N Limit, Mehran Kardar, Miron Kaufman

Miron Kaufman

N color spin models are introduced and examined in the large N limit. The free energy and critical properties at the phase transition are studied. With relevant couplings between colors the transition becomes either first order or Fisher renormalized. With irrelevant couplings there is a crossover to first-order transitions through a nonclassical tricritical point. Connections are established between the N-color model, compressible systems, and systems with random impurities.

Go to article

Random-Field Critical Behavior And The Ginzburg Criterion, Miron Kaufman, Mehran Kardar Mar 1985

Random-Field Critical Behavior And The Ginzburg Criterion, Miron Kaufman, Mehran Kardar

Miron Kaufman

The Ginzburg criterion for crossover from classical to nonclassical critical behavior is derived in the presence of random fields. Experiments on dilute antiferromagnets in a field are examined, and the possibility of such a crossover is investigated. We also point out that the (necessarily) symmetric logarithmic divergence observed in birefringence measurements can be accompanied by a discontinuity, and a fitting form which allows for this and other corrections to scaling is proposed.

Go to article

The Rotated Diffraction Grating: A Laboratory Experiment, James A. Lock Jan 1985