A New Reflective Optical Extensometer (ROX) System for Geomechanical Deformation Measurements A NEW REFLECTIVE OPTICAL EXTENSOMETER (ROX) SYSTEM FOR GEOMECHANICAL DEFORMATION MEASUREMENTS

March 1997 This is a preprint of a paper intended for publication in a journal or proceedings. Since changes may be made before publication, this preprint is made available with the understanding that it will not be cited or reproduced without the permission of the author. PREPRINT ABSTRACT We have developed an extensometer for measurement of distance and displacements in geotechnical and civil engineering applications. This is an optical extensometer that measures distance using a modulated laser beam. In this design, reflecting targets are placed at desired measurement locations, and distance between each target and an optical head are measured repeatedly using the modulated laser beam. Moreover, all electronic and moving parts are located outside of the hostile or difficult environment as the optical head is connected to the laser, switching and signal analysis hardware using optical fibers. A reference beam is utilized to provide direct correction of system behavior. The system also utilizes movable reflective anchors that can be repositioned if desired. We have installed the system in a field experiment currently being conducted for the Yucca Mountain Site Characterization Project, and report preliminary results

Project OART: WDM, EDFAs and mixed data rates in a real-world testbed

Pacific Bell, Lawrence Livermore National Laboratory (LLNL), and the University of California at Berkeley have established a joint fiber testbed located in the San Francisco Bay Area. The fiber to be used in the trial is representative of Pacific Bell`s current fiber plant. This ongoing project is a year long collaboration involving the wavelength division multiplexing (WDM) of data and video on a link using erbium doped fiber amplifiers (EDFA). Designated Project OART. for Optical Amplifier Reliability Trial, this project will provide the Network, Technology District of Pacific Bell a valuable testbed for gathering information and experience with future network designs that will use WDM, EDFs, and the simultaneous transmission of high-speed digital and video information. LLN`s interest in this link is driven by a need to evaluate various future means of interconnecting high performance users With high performance storage and computation sites over remote connections. The OART link will consist of a four channel WDM system on a pair of fibers over a link amplified by two pairs of EDFAs. Three wavelengths will be data communication channels transmitted between LLNL in Livermore and UCB in Berkeley at a distance of 98 km. A fourth channel of video will be carried from a Pacific Bell test facility in Concord on 73 km of fiber to a video lab at LLNL

A new reflective optical extensometer (ROX) system for geomechanical deformation measurements

We have developed an extensometer for measurement of distance and displacements in geotechnical and civil engineering applications. This is an optical extensometer that measures distance using a modulated laser beam. In this design, reflecting targets are placed at desired measurement locations, and distances between each target and an optical head are measure repeatedly using the modulated laser beam. Moreover, all electronic and moving parts are located outside of the hostile or difficult environment as the optical head is connected to the laser, switching and signal analysis hardware using optical fibers. A reference beam is utilized to provide direct correction of system behavior. The system also utilizes movable reflective anchors that can be repositioned if desired. We have installed the system in a field experiment currently being conducted for the Yucca Mountain Site characterization Project, and report preliminary results

Spectra of single-bubble sonoluminescence in water and glycerin-water mixtures

A single gas bubble, acoustically levitated in a standing-wave field and oscillating under the action of that field, can emit pulses of blue-white light with duration less than 50 ps. Measurements of the spectrum of this picosecond sonoluminescence with a scanning monochrometer are reported for air bubbles levitated in water and in glycerin-water mixtures. While the spectrum has been reported previously by others for air bubbles in water, the spectrum for air bubbles in water-glycerin mixtures has not. Expected emission lines from glycerin were conspicuously absent, suggesting a different mechanism for light production in single-bubble sonoluminescence. Other conclusions are the spectrum for air bubbles in water is consistent with that previously reported, the radiated energy decreases as the glycerin concentration increases, and the peak of the spectrum appears to shift to longer wavelengths for the water-glycerin mixtures.This work was supported in part by the Office of Naval Research, the Defense Nuclear Agency, and the Naval Postgraduate School Research Program. The authors wish to thank David Cleary for the use of the scanning monochrometer and D. Scott Davis for many helpful discussions

Photonic doppler velocimetry

We are developing a novel fiber-optic approach to laser Doppler velocimetry as a diagnostic for high explosives tests. Using hardware that was originally developed for the telecommunications industry, we are able to measure surface velocities ranging from centimeters per second to kilometers per second. Laboratory measurements and field trials have shown excellent agreement with other diagnostics

High-accuracy calibration of an adaptive optics system using a phase shifting diffraction interferometer

A phase-shifting diffraction interferometer (PSDI) has been integrated into an adaptive optics (AO) system developed by LLNL for use on the three meter Shane telescope at Lick Observatory. The interferometer is an all fiber optic design, which is extremely compact. It is useful for calibrating the control sensors, measuring the aberrations of the entire AO optical train, and measuring the influence functions of the individual actuators on the deformable mirror. The PSDI is particularly well suited for this application because it measures converging, quasi-spherical wavefronts, such as are produced by an AO imaging system. Thus, a PSDI can be used to measure the aberrations of the entire AO system, in-situ and without errors introduced by auxiliary optics. This provides an extremely accurate measurement ({approximately} 5 nm RMS) of the optical properties of the AO system

Application of optical interconnect technology at Lawrence Livermore National Laboratory

Optical interconnects will be required to meet the information bandwidth requirements of future communication and computing applications. At Lawrence Livermore National Laboratory, the authors are involved in applying optical interconnect technologies in two distinct application areas: Multi-Gigabit/sec Computer Backplanes and Gigabit/sec Wide Area Networking using Wavelength Division Multiplexing. In this paper, the authors discuss their efforts to integrate optical interconnect technologies into prototype computing and communication systems