Abstract: Optical guiding of intense laser pulses over a distance of more than one Rayleigh length in a plasma is discussed herein using a multi-pulse technique. The first pulse or pulse sequence prepares a shock-driven, axially-extended radial electron density profile which guides a second pulse or sequence of pulses. The profile is also capable of guiding x-rays. The channel will support mode structure exactly analogous to that of an optical fiber waveguide. The method provides a means for guiding of a high intensity optical laser pulse or x-rays over distances well in excess of a Rayleigh length. The distances over which guiding occurs is limited only by the length of the preformed plasma and absorption and possible backscattering of the guided EM radiation. Applications of the method allow for compact x-ray laser devices and electron particle accelerators.

Abstract: A precoding scheme for noise whitening on ISI channels is presented where the scheme permits any type of shaping and is compatible with trellis coding. Its implementation complexity is significantly less than that of trellis precoding. The resulting reduction in shaping gain is small and becomes negligible as the rate per 2D of the constellation increases. This technique uses a structured vector quantization (SVQ) technique for optimal shaping of the constellation. Optimal (N-sphere) SVQ shaping results in higher shaping gains than those of Voronoi constellations based on known N-dimensional lattices. For a given CER.sub.2 (or PAR.sub.2) SVQ shaping results in optimal shaping. This is useful for implementation over QAM modems as significant shaping gains can be achieved even for a small constellation expansion. The SVQ-shaped constellations have a very reasonable implementation complexity.

Abstract: A sensing system for accurately monitoring the position and orientation of an object (28). At least 4 point light sources (26) are mounted on the surface of the object (28). A single electronic camera (20) captures images (92) of the point light sources (26). Locations of these images (92) are detected in each camera image, and a computer runs an iterative task using these locations to obtain accurate estimates of the pose of the object (28) in a camera coordinate system (90) at video rate. The object is held by an operator (40) for cursor (60) control, for interaction with virtual reality scenes on computer displays (22), or for remote interactive control of teleoperated mechanisms.

Abstract: The invention uses a heterodyne interferometer with coherent detection that uses a vibrating sample that can be used as a non-contact and non-destructive surface profiler and mapping apparatus where detailed profiles of the local slope and/or roughness of the vibrating sample are obtained in three dimensions. The invention can operate in either a heterodyne or homodyne regime with a probe that uses either i) focused optics, ii) a single mode optical fiber with an integral GRIN lens at its far end for focusing onto the sample or iii) a single-mode optical fiber with a taper at the end. Additionally, the heterodyne interferometry technique can be used for imaging birefringent objects such as semiconductor diagnostics of GaAs, InGaAs, InGaAsP, and other II-VI of III-V binary, ternary, and quaternary materials for analysis and diagnostics by using the birefringent properties of the object, and monitoring the electrical activity of biological cellular tissue.

Abstract: This invention pertains to an integral Fabry-Perot stress corrosion, strain and material corrosion sensor and associated system that allows for in-situ monitoring of stress-corrosion, strain and corrosion at a given location of a specimen in real-time. The sensor uses an intrinsic Fabry-Perot cavity with one mirror integrally mounted on the specimen that provides a means for: i) transducing information of stress-corrosion of the specimen; ii) measuring strain of the specimen; and iii) measuring the corrosive environment.

Abstract: The invention describes a real-time in situ ellipsometric monitoring and control system using an ellipsometer to control the averaged refractive index of the deposited film during the AR coating of semiconductor laser diode facets for laser amplifiers and superluminescent LED. The input and output window birefringences are taken into account and calibrated the windows mounted on the vacuum chamber to include the effects of the pressure and mounting stress. In addition to the conventional four-medium model which gives an averaged refractive index, an adaptive multilayer model which takes into account an increasing number of layers as the evaporation proceeded is developed to monitor the instantaneous changes of the refractive index. Each ellipsometric measurement lasts only 0.5s and provides two sets of refractive index and thickness data as derived by the two multilayer models. Both measured data are used for the refractive index control to achieve a good feedback response.

Abstract: A parallel dilating-filters switched-capacitor filter bank is described in simulation of the cochlea. Area-saving is achieved by filter-sharing, effective sum-gain amplifier designs, and using area efficient nth-order filter designs, and in particular using a biquadratic filter design using charge-differencing. The structure is easily expandable to include more channels by extending with additional filters and output amplifiers, or by using several chips with different sampling frequencies in parallel connection. An offset-compensated area-efficient switched-capacitor sum-gain amplifier circuit design is described and can be used in the filter bank.

Abstract: A pointing device (28), comprising light sources (30) and monitored by a computer vision task running in a microcontroller (108) and a computer (24). The computer vision task computes the spatial position and orientation of the pointing device, and enables an operator to control virtual three dimensional objects (73) on the display (22) of the computer. Images (78) are captured by a video camera (20) and digitized, and only image rows that contain bright pixels (80) from the light sources are processed. The light sources are the tips of optic fibers (30) guiding light from a laser diode (32), and an optical filter (46) on the camera is matched to the wavelength of the laser diode.

Abstract: A number of resonant tunneling diodes are connected in series with a resistor, a current source or a load device. A bit line is connected to every joint between any two devices through a switch. When properly biased, there can be (N+1).sup.m number of stable quantized operating points which are represented by a combination of m variables (of either voltage or current, where N is the number of peaks of the folding I-V characteristic and m is the number of bit lines. The m bit lines can write in (N+1).sup.m different combinations of inputs. During reading, the quantized voltage (or current) at each bit line is sensed. The number of stable states can be doubled by changing the polarity of the power supply.

Abstract: Optical fiber sensor coated with linear work hardening elastic-plastic materials is provided that are used for a non-destructive optical damage detection sensor. The detection coating's intrinsic and extrinsic properties are critical on the sensor's continuous performance while being subjected to adverse environmental conditions. The damage detection sensor can also be used as an alternative to the conventional fiber fracture sensor for sensing impact damage. Other uses include maintaining a permanent record of the load/damage history of a loaded structure. A simple damage detection system is described that detects the sensor's permanent output phase-shift.

Abstract: A new and innovative concept for the control of backlash in gear-coupled transmission mechanisms. The concept utilizes redundant unidirectional drives to assure positive coupling of gear meshes at all times. Based on this concept, a methodology for the enumeration of admissible redundant-drive backlash-free robotic mechanisms has been established. Some typical two- and three-DOF mechanisms are disclosed. Furthermore, actuator torques have been derived as functions of either joint torques or end-effector dynamic performance requirements. A redundantly driven gear coupled transmission mechanism manipulator has a fail-safe advantage in that, except of the loss of backlash control, it can continue to function when one of its actuators fails. A two-DOF backlash-free arm has been reduced to practice to demonstrate the principle.

Abstract: A sensing system for monitoring the position and orientation of a rigid object (20). At least 4 point light sources (24) are mounted on the surface of the object (20) in a noncoplanar arrangement. A single electronic camera (26) captures images (59) of the point light sources (24). Locations of the images (59) of the light sources (24) are detected in each video image, and a computer runs a task using these locations to obtain close approximations of the rotation matrix and translation vector (33) of the object (20) in a camera coordinate system (74) at video rate. The object is held by an operator (90) for three-dimensional cursor (94) control and interaction with virtual reality scenes (96) on computer displays (88), and for remote interactive control of teleoperated mechanisms.

Abstract: An active monolithic optical device for wavelength division multiplexing (WDM) incorporating diode laser arrays, an output coupling waveguide and a curved Rowland circle based grating to produce a plurality of individual laser beams at slightly different wavelengths is integrated in a common electro-optic material. The wavelength of each laser source is determined by the geometry of the array and the diffraction grating design. The output of all the channels can be collected into a concentrator or lens to be multiplexed in a single output. Applications include a WDM optical amplifier and WDM laser source.