Stiffer optical tweezers through real-time feedback control

Using real-time re-programmable signal processing we connect acousto-optic steering and back-focal-plane interferometric position detection in optical tweezers to create a fast feedback controlled instrument. When trapping 3 µm latex beads in water we find that proportional-gain position-clamping increases the effective lateral trap stiffness ~13-fold. A theoretical power spectrum for bead fluctuations during position-clamped trapping is derived and agrees with the experimental data. The loop delay, ~19 µs in our experiment, limits the maximum achievable effective trap stiffness

A Scalar Wigner Theory for Polarized Light in Nonlinear Kerr Media

A scalar Wigner distribution function for describing polarized light is proposed in analogy with the treatment of spin variables in quantum kinetic theory. The formalism is applied to the propagation of circularly polarized light in nonlinear Kerr media and an extended phase space evolution equation is derived along with invariant quantities. We further consider modulation instability as well as the extension to partially coherent fields.Comment: 6 page

The Uncertain Scope of the Plain View Doctrine

In recent years the Supreme Court has expanded the plain view exception to the warrant requirement by relaxing the prior valid intrusion and the inadvertency requirements. This article examines the resulting confusion in the state courts and identifies areas where judicial clarification is needed

The Uncertain Scope of the Plain View Doctrine

In recent years the Supreme Court has expanded the plain view exception to the warrant requirement by relaxing the prior valid intrusion and the inadvertency requirements. This article examines the resulting confusion in the state courts and identifies areas where judicial clarification is needed

Letter from E. A. Wallin

Letter concerning a copy of the catalogue for Utah Agricultural College