Volume 75, Issue 8, August 2004
Index of content:
75(2004); http://dx.doi.org/10.1063/1.1777387View Description Hide Description
This work describes the production of microcantilever beams via a solvent casting technique. The beams produced had dimensions of roughly 500 by 50 by (length, width, and thickness, respectively). A subset of the beams produced were characterized and were shown to have comparable dynamic mechanical behavior as that of existing ceramic and photopolymer microcantilevers.
75(2004); http://dx.doi.org/10.1063/1.1777386View Description Hide Description
In scanning probe microscopy, it is critical to maintain small probe sample separations for high resolution imaging. Quartz crystal tuning forks are typically used for detecting shear forces in near-field scanning optical microscopy and normal forces in other atomic force-related microscopies. In this article we compare several tuning fork based detection schemes to determine which solution gives the best signal to noise ratio. The high impedance and low signals produced by the tuning fork necessitate care in selection of an appropriate preamplifier. We find that a carefully guarded voltage preamplifier sensing a mechanically driven tuning fork performs the best, but an electrically driven fork with a current preamplifier offers simpler construction with only 25% lower signal to noise ratio on average.
75(2004); http://dx.doi.org/10.1063/1.1777407View Description Hide Description
We demonstrate the capability of a commercial photomultiplier to produce distinguishable anodic-pulse charge values when 1, 2, or more photoelectrons leave the cathode within a time shorter than the pulse-response duration. We propose a method for precise reconstruction of the photoelectron statistics from the measured pulse-height spectra and discuss applications to the characterization of quantum states in the continuous-variable regime.
Compact high-voltage generator of primary power based on shock wave depolarization of lead zirconate titanate piezoelectric ceramics75(2004); http://dx.doi.org/10.1063/1.1771490View Description Hide Description
The design and performance of a compact explosive-driven high-voltage primary power generator is presented. The generator utilizes a fundamental physical effect—depolarization of ferroelectric materials under longitudinal shock wave impact, when the shock wave is initiated along the polarization vector . These primary power sources, containing energy-carrying elements made of lead zirconate titanate poled piezoelectric ceramics, with the volume from 0.35 to , are capable of producing pulses of high voltage with amplitudes up to . The amplitude and full width at half-maximum of the high-voltage pulses are directly proportional to the thickness of the energy-carrying element, with coefficients of proportionality of (amplitude) and (width). The specific energy density of these ferroelectric energy-carrying elements reaches .
75(2004); http://dx.doi.org/10.1063/1.1771498View Description Hide Description
A relatively simple and inexpensive apparatus for the measurement of magnetostriction in bulk samples at room temperature and above is described. A laser beam directed into a four-quadrant photodiode is partially blocked by the free end of the strip sample. When the sample changes length under the influence of an applied field, the output of the photodiode segments is unbalanced, producing a signal that is proportional to the change in length over a range of about . The laser beam is modulated at , and the photodiode signal measured with a lock-in amplifier. The sample can be moved vertically with a fine screw thread, which is used both for calibration and to offset the effect of thermal expansion. The samples are metallic strips long by about wide and generally about thick. They can be heated in air to a maximum temperature of about . The sensitivity of the apparatus is about at room temperature, falling to about at , which is adequate for strongly magnetostrictive materials. Measurements have been made on several alloys, as well as , , and alloys.