Photonics East highlights communications and intelligent systems

Currently in its second year, Photonics East (Oct. 22-26, Philadelphia, PA) is a multidisciplinary conference organized around two symposia. One is a continuing symposium entitled Intelligent Systems and Advanced Manufacturing. The other is the newly created Voice, Video, and Data Communications, a combination of previously existing conferences in electronic imaging and broadband communications.

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Photonics East highlights communications and intelligent systems

Kristin Lewotsky

Currently in its second year, Photonics East (Oct. 22-26, Philadelphia, PA) is a multidisciplinary conference organized around two symposia. One is a continuing symposium entitled Intelligent Systems and Advanced Manufacturing. The other is the newly created Voice, Video, and Data Communications, a combination of previously existing conferences in electronic imaging and broadband communications.

The 34 technical conferences included in the meeting offer a total of 1050 papers, roughly 15% of which are from international authors. Organizers at SPIE (Bellingham, WA) anticipate roughly 5000 attendees at the event. Expected to draw around 270 different companies, the exhibit is divided into three pavilions: Electronic Imaging International, Broadband Communications Expo `95, and Photonics Engineering Northeast. The exhibit will include a pair of activity spaces similar to the Photonics West Technology Town Squares, introduced in February (San Jose, CA). They will feature various types of interactive demonstrations and special exhibits.

Intelligent transportation systems

In 1994, Photonics East featured the first SPIE conference on intelligent transportation systems (ITSs). In an effort to better address the needs of the engineering and ITS community, the ITS conference has been split up into sessions on collision avoidance, automated traffic management, and mobile robots. The collision-avoidance and automated-traffic-management sessions will be devoted to sensors and machine-vision systems for "smart" cars and highways. The mobile-robots conference includes a session on technology for automated vehicles.

In 1991 the US Congress allocated $660 million to a six-year ITS development program. A significant amount of research and development is taking place in this area, a sampling of which will be presented in the Collision Avoidance and Automated Traffic Management Sensors technical conference. "What we would like to do," says conference chair Alan Chachich, "is attract more technical people into an application area that they may not be familiar with. The technology people are the `answer` people, and the transportation people are the `question` people. What we`re trying to do is bring them together." Optical technology answers for ITS include sensors, machine-vision systems, and communications.

Salvatore D`Agostino of Computer Recognition Systems (CRS, Cambridge, MA) will discuss the optical elements of an electronic vehicle toll collection system currently being tested on the Carquinas Bridge in California (paper #2592-02). While the electronic system reads the signal from a vehicle-identification transponder and writes a new balance to the vehicle toll account, a CRS machine-vision system performs vehicle classification to verify that the transponder code matches the actual vehicle. Vehicles passing through nonautomated toll gates will also be monitored for toll compliance. D`Agostino will also discuss developments in optical ITS technology and emerging applications such as speed control, intelligent intersection control, high-occupancy vehicle enforcement, and traffic-analysis surveys.

Sensor technology is an integral part of ITSs. Embedded extrinsic Fabry-Perot interferometric fiberoptic sensors are being tested for vehicle detection in a system developed by researchers at the Fiber & Electro-Optics Research Center (FEORC, Virginia Polytechnic Institute and State University, Blacksburg, VA). Group leader Marten de Vries will discuss fiberoptic sensors for "smart" structures and their use in such ITS applications as vehicle speed and flow evaluation or vehicle weigh-in-motion measurements (paper #2592-05). In particular, de Vries will discuss results from field trials of the FEORC sensors, devices that may find applications in traffic monitoring or as traffic-light triggers (see Fig. 1).

A diode-laser-based device developed for the US Department of Transportation can detect vehicle weaving due to driver fatigue or intoxication, as William Bachalo of Aerometrics (Sunnyvale, CA) will describe (paper #2592-16). Output from the diode laser is scanned across the roadway with a rotating prism and reflected by the lane markers or lines (see Fig. 2). A signal processor equipped with a master clock correlates reflected signal detection with the angular position of the outgoing beam, yielding position of the vehicle with respect to road lines.

As anyone who`s ever driven in the winter or in late afternoon sun knows, environmental conditions wreak havoc with the signal-to-noise ratio of optical sensors. Developing operational devices is not enough; engineers must understand how they operate under a variety of conditions. Jeffrey Everson of Battelle Memorial Institute (Cambridge, MA) has simulated the effects of adverse weather on roadway imagery and will discuss the effects of environment on sensor and image-processor performance (paper #2592-16).

Voice, video, and data communications

Monolithic integration appears to be critical to the realization of high-speed, all-optical networks. Says Emil Koteles, cochair of the conference on Emerging Components and Technologies for All-Optical Networks, "Only with some simple, cheap, and reliable technique for integrating optoelectronic devices of differing functionalities on a single wafer will the promise of the information superhighway be fulfilled."

Using ion implantation to modify the bandgap of quantum-well structures, researchers at the Institute for Microstructural Sciences (Ottawa, Canada) and the University of Western Ontario (London, Canada) are able to integrate multiple devices such as lasers, detectors, and modulators on a single substrate (paper #2613-03). The implantation creates vacancies and interstitials in the device, which, upon annealing, result in a blue shift of the quantum-well bandgap. Masking during implantation allows blue shift to be varied in different locations on a wafer, resulting in monolithic integration of various devices. Group member P. J. Poole will discuss the methodology and present the performance of recent devices produced with this technique.

Monolithically integrated, indium phosphide (InP) wavelength-dispersive devices are the subject of a talk by

J. Soole of Bellcore (Red Bank, NJ; paper #2613-07). The two basic device types are etched reflection-grating spectrograph and waveguide phased-array grating multiplexer/demultiplexer. Soole will discuss the integration of the dispersive elements with other active components to form wavelength-division-multiplexed lasers and detectors. Michael Schilling of Alcatel-SEL (Stuttgart, Germany) will review recent research and development activities in InP-based components, with emphasis on the production of simple photonic integrated circuits for transmission and switching (paper #2613-01).

An all-optical network testbed including such novel components as fast-tuning, 1.5-µm distributed-Bragg-reflector lasers, passive wavelength routers, and broadband optical-frequency converters, has been developed by a consortium made up of AT&T Bell Laboratories (Crawford Hill, NJ), Digital Equipment Corp. (Littleton, MA), and MIT Lincoln Laboratory (Lexington, MA). Network applications dynamically allocate optical bandwidth between electronic packet switches based on user load, and the network is capable of supporting multiple services with data rates as high as 10 Gbit/s/ user. Douglas Marquis of Lincoln Laboratory will provide a description of network design and applications (paper #2614-06), while a second paper, delivered by Mark Stevens of Lincoln Laboratory, will focus on the component technology and physical layer comunications.

Other highlights

A 24 ¥ 24 ¥ 32-mm optical scanning sensor for pipe inspection has been developed as a possible scanning device for self-propelled inspection robots, reports Hiromi Totani of OMRON Corp. (Ibaraki, Japan) in paper #2593-03. In the same session, Roland Buechi of the Swiss Federal Institute of Technology (Zurich, Switzerland; paper #2593-05) discusses a 20 ¥ 8 ¥ 15-mm robot built with coworkers. Fitted with infrared sensors, the device is capable of following a black line printed on the ground.

The application of imaging spectrometry (so-called hyperspectral imaging) to industrial inspection will be discussed by both Charles Willoughby of TRW (Los Angeles, CA; paper #2599-27) and Steven Babey of ITRES Research Ltd. (Calgary, Canada; paper #2599-32). Imaging spectrometry has been well developed for remote-sensing applications and instruments operating in the visible, and infrared spectral regions offer powerful methods for industrial inspection.

The papers mentioned in this article represent only a fraction of the total technical presentations at Photonics East this year. With additional conferences in precision plastic optics, optical data storage, machine vision, and optical wireless communications, it promises to be a meeting packed with technical information. n

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FIGURE 1. Virginia Tech students Dave Forbis and Cindi Grinder install extrinsic Fabry-Perot interferometric fiberoptic sensors in testbed on

Virginia Tech campus. The sensors were later covered with asphalt.

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Click here to enlarge image

FIGURE 2. Spinning prism laterally scans output from a diode laser in a vehicle-position detector developed by Aerometrics Inc. Voltage pulse indicates that the target (lane marker) has been acquired, and a master clock in the processor correlates the signal pulse with scan position to determine vehicle position within the lane (inset).

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