PROCEEDINGS ARTICLE | September 17, 2011
Proc. SPIE. 8097, Optical Trapping and Optical Micromanipulation VIII
KEYWORDS: Polarization, Wavefronts, Ultrasonics, Optical tweezers, Transducers, Quantum mechanics, Acoustics, Spiral phase plates, Systems modeling, Phase shifts
When samples of interest are small enough, even the relatively weak forces and torques associated with
light can be sufficient for mechanical manipulation, can offer extraordinary position control, and can
measure interactions with three orders of magnitude better resolution than atomic force microscopy.
However, as the components of interest grow to slightly larger length scales (which may yet be of interest
for microfluidic, "lab-on-a-chip" technologies and for research involving biomedical imaging), other
approaches gain strength. This paper includes discussion of the angular momentum carried by sonic beams
that we have implemented both to levitate and controllably rotate disks as large as four inches across.
Discussion of such acoustic beams complements the discussion of the angular momentum carried by light
and, by further analogy, how we view stationary states discussed in quantum mechanics. Hence, a primary
use of the sonic screwdriver is as a model system, although these beams are useful for a variety of other
reasons as well (not least for aberration correction for ultrasonic array systems). Methods, including the use
of holographically structured fields, are discussed.
