Thick transducers used for generating short-duration stress pulses in thin specimens

By generating short stress pulses with thick transducers, the pulse-echo method for determining sound velocities and acoustic attenuation can be applied to thin specimens. The stress pulses enter a specimen where one pulse is reflected several times before a succeeding pulse enters the specimen

Parametric frequency conversion of coherent light by the electro-optic effect in KDP

We report an experiment in which interaction between an optical wave at frequency f0 and a microwave signal at fm was used to generate a coherent optical beam at f0 + fm. The interaction was provided by lossless electro-optic modulation of the dielectric constant within a laser resonator and can thus be viewed as a demonstration of parametric(3-5) interaction at optical frequencies

Interferometry and Laser Control with Solid Fabry-Perot Etalons

The use and analysis of solid Fabry-Perot etalons for interferometry and laser control are discussed and supported with experimental data. Low angle scattering is found to be an important factor influencing finesse and peak transmission. Thermal tuning sensitivity and wedge-angle control with thermal gradients are analyzed and illustrated. Control of laser oscillations using a solid-state etalon as a laser cavity end mirror is discussed. The use of the solid etalon as an optical cavity coupler is applied to the problem. of sideband energy removal from an internally modulated laser

On some lattice computations related to moduli problems

We show how to solve computationally a combinatorial problem about the possible number of roots orthogonal to a vector of given length in $E_8$. We show that the moduli space of K3 surfaces with polarisation of degree 2d is also of general type for d=52. This case was omitted from the earlier work of Gritsenko, Hulek and the second author. We also apply this method to some related problems. In Appendix A, V. Gritsenko shows how to arrive at the case d=52 and some others directly.Comment: With an appendix by V. Gritsenk

Flow angle sensor and readout system

Sensor determines fluid flow angles by means of a simple vane that positions itself in the direction of the flow. The vane rotates a small light-reflecting disc as it moves while the readout system uses two cyclically polarized light beams

Millivolt signal limiter

Low-voltage limiter circuit suppresses the output of platinum probes at temperatures beyond their operating range. The limiter circuit comprises an operational amplifier with a dual feedback loop. The signal limiter is useful in low-voltage instrumentation circuits normally operable or set for cryogenic temperatures

Interdisciplinary applications and interpretations of remotely sensed data

An interdisciplinary approach to use remote sensor for the inventory of natural resources is discussed. The areas under investigation are land use, determination of pollution sources and damage, and analysis of geologic structure and terrain. The geographical area of primary interest is the Susquehanna River Basin. Descriptions of the data obtained by aerial cameras, multiband cameras, optical mechanical scanners, and radar are included. The Earth Resources Technology Satellite and Skylab program are examined. Interpretations of spacecraft data to show specific areas of interest are developed

Electronic high pass filter

Ultra accurate filter is used with static type pressure transducers where it is desirable to extract low frequency dynamic signals from combined static and dynamic signal. System can be calibrated at any time with dc voltages