Samuel M. Goldwasser

Physician's Workstation with Real-Time Performance

A general framework for real-time manipulation-of 3D objects from-medical data sets promises physicians a powerful new tool.

Real-time display and manipulation of 3-D medical objects: the Voxel processor architecture

The fundamental problems associated with the interactive display, manipulation, and editing of three-dimensional (3-D) objects obtained from medical imaging systems such as CT, PET, and MRI are addressed. Software, hardware, and firmware techniques for shaded graphics display of medical objects are described and evaluated in terms of flexibility and performance. A special purpose multiprocessor architecture (the Voxel Processor architecture) developed specifically for medical research, clinical diagnosis, and surgical planning is presented. The Voxel Processor implements a shaded graphics display system with rotation, scaling, translation, slice planes and tone scale transformations on gray-scale data in true real time. The high-speed image generation algorithms exploit the ability to partition object space and require only simple arithmetic and logical operations. Minimal preprocessing steps are required to prepare object data for the Voxel Processor, and the data are always readily accessible for analysis or editing. The architecture is highly structured and is ideally suited for VLSI implementation.

A generalized object display processor architecture

The features and organization of a hardware architecture that is designed to facilitate the real-time display and manipulation of a single three-dimensional object on a raster-scan video display are briefly summarized. The author then outlines the major features of an extension to the architecture that will permit the high-speed display and manipulation of multiple, independent, shaded three-dimensional objects represented as a voxel (volume-element) database with gray scale. The objective is to provide many useful capabilities at or near video rates facilitating extensive real-time interaction. The architecture is highly modular, permitting a cost tradeoff to be made to achieve a given level of performance. It also includes a great deal of regularity in its structure, making it directly suitable for VLSI implementation. A key feature is that no computational operations more complex than adds, shifts, and comparisons are required in real time. The display characteristics for each object are controlled by a concise object descriptor table, which contains all of the control parameters required to process that object.

Rapidly tunable millimeter-wave optical transmitter for lidar-radar

This paper reports on the optical generation of a rapidly tunable millimeter-wave subcarrier for lidar-radar. The millimeter-wave signal is generated by beating the output from two Nd:YVO/sub 4//MgO:LiNbO/sub 3/ electrooptical monomode microchip laser sections realized monolithically in a single composite crystal. The device has a continuous tuning range up to 45 GHz. The measured chirp rate is 3816 THz/s, the voltage sensitivity is 10.6 MHz/V, and the measured residual phase noise is -106 dBc/Hz at 10-kHz offset.

Techniques for the rapid display and manipulation of 3-D biomedical data.

The use of fully interactive 3-D workstations with true real-time performance will become increasingly common as technology matures and economical commercial systems become available. This paper provides a comprehensive introduction to high speed approaches to the display and manipulation of 3-D medical objects obtained from tomographic data acquisition systems such as CT, MR, and PET. A variety of techniques are outlined including the use of software on conventional minicomputers, hardware assist devices such as array processors and programmable frame buffers, and special purpose computer architecture for dedicated high performance systems. While both algorithms and architectures are addressed, the major theme centers around the utilization of hardware-based approaches including parallel processors for the implementation of true real-time systems.

Receiver for a coherent fiber-optic link with high dynamic range and low noise figure

Phase modulated coherent fiberoptic links can potentially provide exceptionally high spurious free dynamic range (SFDR) and low noise figure (NF). Critical issue is the development of a strictly linear phase demodulator. In this paper we describe a phase demodulator employing a phase locked loop discriminator. Implementing the PPLL on a single substrate using the state-of-the-art components could yield an SFDR better than 145 dB/Hz2/3 and NF lower than 3dB.

A Two-Channel Picture Coding System: I--Real-Time Implementation

The two-channel system previously reported has been implemented in hardware using system parameters appropriate to consumer television. The basic system divides the spectrum into lowand high-frequency spatial components. The lows are coarsely sampled and finely quantized and the highs finely sampled and coarsely quantized using a companded, randomized quantizer. The purpose of this experiment was to demonstrate the potential of the system for low-cost practical application, to study the effect of the character of the randomizing noise, and to ascertain that there were no deleterious effects due to interlace, motion, or input noise. Theoretical noise calculations were qualitatively confirmed.

Optically generated dynamically tunable, low noise millimeter wave signals using microchip solid state lasers

This paper concerns the optical generation of microwave and millimeter wave signals by heterodyning two or more solid state microchip lasers. The lasers can be temperature and voltage tuned to produce beat frequencies up to 200 GHz with tuning speed of 50GHz/microsec. A novel fiberoptic delay is employed to stabilize the transmitter yielding a measured phase noise of -101 dBc/Hz at 10 kHz offset.

Coherent optical vector modulation for fiber radio using electrooptic microchip lasers

Future communication systems will require high data rates and flexible modulation. Direct optical phase modulation of two microchip lasers by information-bearing signals allows for high-rate delivery via fiber to a basestation. At the basestation, the coherent optical signals are combined with a reference in a photodetector to produce a microwave/millimeter-wave carrier with arbitrary M-ary quadrature amplitude modulation, which can then be transmitted over a wireless channel. Rapid tuning of the microwave/millimeter-wave carrier, the modulation scheme, and the data rate is achievable through this method with no fixed oscillators at the basestation, thus providing for flexible architectures. Results show a high-quality carrier and, for 4- and 16-QAM, with data rates to 200 Mb/s. Extensions to higher data rates are discussed.

Computer architecture for grasping

The Integrated Tactile Network Architecture or ITNA is a hierarchical system for managing the interaction of tactile sensing and motor control in the 3-D active sensory environment. The overall ITNA includes custom dedicated hybrid front end tactile arrays incorporating electronics and microprocessors for sensor linearization, tactile information preprocessing, and local feature extraction approaches to the distributed motor control of manipulator fingers for grasping; interconnection networks for guarded movement and reflex arcs; and special purpose hardware for model generation derived from tactile information. This paper primarily addresses the overall ITNA structure and, in particular, the design of an intelligent sensor array and its associated communications subsystem.