The benefits of fiber optics for telecommunications and Local Area Networks (LANs) are well documented. The benefits to passenger car applications are not as clearly defined. This paper examines the differences between Telecommunications, LAN, and automotive point to point and network applications. Current production automotive applications of optics and fiber optics, automotive data communications trends, and both functional and non-functional requirements and constraints will be described.

The applications for plastic optical fibers (POF) have been expanding in recent years, as advantages of their properties over silica and glass optical fibers have become recognized. The automotive industry, in particular, has afforded one of the most fertile fields in which POF demonstrate their superior properties. This paper will outline the optical characteristics and physical properties of POF, which include the heat resistant type POF. Recent applications for POF in the automotive industry, such as ribbon illuminators and optical taps for data transmission links, are also described.

This paper describes the development of a plastic optical fiber composed of a poly carbonate core with a glass transition temperature of 150°C, and a cladding of newly developed poly 4-methyl pen ten -1 which softens at 1.73°C. This caldding is suitable for use at temperatures up to 130°C. The minimum optical attenuation is 0.8dB/m at 765nm in the near infrared region. The cause of the attenuation of the PC-core fiber was analyzed and the intrinsic loss limit was estimated to be 0.4dB/m at 765nm. The fiber has excellent characteristics, includiing thermal stability up to 125°C, high flexibility, high strength, and self-extinguishing properties. The polycarbonate core fiber doped organic fluorescence has been also developed for automotive use such as light guide and illumination. This fiber can be transmitted the incident optical beam perpendicular to the fiber as well as the beam parallel to the fiber.

Polymer 1 X 2 couplers were fabricated using multimode optical waveguide circuit tech-niques which are amenable to low-cost production strategies. Optical circuit design and basic materials were selected to enable the couplers to be compatible with 250 μm diameter Eska-10(R) plastic fiber. The "all polymer" coupler, with input and output plastic fiber pigtails, had an excess loss of less than 2 dB and a loss uniformity of 0.8 dB at 820 nm. Variations in excess loss were 1 dB over a wavelength range from 420 to 850 nm. Directivity values of 25 ± 5 dB were measured and coupler performance was found to be only minimally affected by temperature over the range of 0 to 70°C.

Optical fiber sensing technologies are expected to apply for many future electronic control systems in automobiles, because of their original outstanding features, such as high noise immunity, high heat resistance, and flexible light propagation paths which can be applicable to measure the movements and directions of the mobiles. In this paper, two typical applications of fiber sensing technologies in automobiles have been described in detail. The combustion flame detector is one of the typical applications of a fiber spectroscopic technology which utilizes the feature of high noise and heat resistibility and remote sensibility. Measurements of engine combustion conditions, such as the detonation, the combustion initiation, and the air-fuel ratio, have been demonstrated in an experimental fiber sensing method. Fiber interferometers, such as a fiber gyroscope, have a lot of possibilities in future mobile applications because they are expandable to many kinds of measurements for movements and physical variables. An optical fiber gyroscope utilizing the single polarized optical fiber and optical devices has been developed. Quite an accurate measurement of vehicle position was displayed on a prototype navigation system which installed the fiber gyroscope as a rotational speed sensor.

This paper describes a microbend amplitude sensor for measurement of engine internal combustion pressure. Utilizing a step index singlemode fiber in a spark plug washer-type configuration, it is a simple, sensitive and rugged design. The microbending element, composed of two serrated washers constraining an optical fiber loop, responds to spark plug displacement arising from the combustion cycle. The response of the sensor is linear in dB with displacement and force over a wide dynamic range. We compare performance under static and running engine conditions with a research grade piezoelectric diaphragm sensor and a piezoelectric washer-type sensor.

A miniature fiber-optic accelerometer was constructed and tested. Optical phase modulation was employed. A multimode diode laser served as the optical source for the single-mode optical fiber. The resulting sensor element is 2.5 cm long and 0.25 mm in diameter. The acceleration range measured extended from below 104g to above 3g. The upper limit was due to limitations in the test equipment rather that the accelerometer. The device was designed to operate to above 10g. The frequency range investigated was 100 Hz to 25 kHz. Here again the upper frequency was limited by the test equipment. An undesirable cross-axis resonance was observed at 2.8 kHz. Techniques for moving this resonance to above the operating range are described.

A versatile communication system in a ship with 120 stations, each having voice and data transmission is envisaged. The proposed fibre optic network has a bus topology ideally suited for distribution in ship-like environment. Use has been made of standard ETHERNET chip sets manufactured by INTEL. This makes the stations compact, easier to maintain and inexpensive. The ETHERNET proto-col is primarily designed for packet data transmission. The collision detection and backoff protocol makes the packet transmission probabilistic and is therefore not suitable for voice transmission. This problem is overcome in the present design by a scheme where the required number of voice slots are dynamically allocated. That is, having established a connection for voice communication between stations, fixed slots are assigned for voice transmission and reception. The data transmission continues to use CSMA/CD Protocol. A simple hardware addition to the ETHERNET chip set makes the scheme workable. Drops in the fiber optic bus network is through passive star couplers. Four to eight star couplers are used in the present scheme with repeaters between adjacent star couplers. The repeaters will not be usual repeaters, as ordinary repeaters would cause loops to be formed between adjacent stars, thereby causing data to recirculate. This recirculation is avoided by making the repeater intelligent and also performing the task of detecting collisions between signals originating from stations connected to different star couplers.

The shipboard environment, with its potential for extreme EMI levels, electrical problems, flooding, fire and other damaging conditions, is particularly well suited to benefit from fiber optic based sensing technology. Fiber optics can contribute significantly to platform mission readiness, survivability and maintainability. Suitable sensors, when combined with modern concepts of multiplexing, data busing, and computer-based data processing and control, offer significant benefits. Such systems can help eliminate unintended electromagnetic radiation, reduce crew workload, simplify system overhaul or upgrade, decrease weight and allow for the deployment of composite ship structures. However, one essential element of such a system is the development of diverse, high performance, moderately priced sensors using fiber optic signal lines. Eldec Corporation has been involved in the development of such sensors and this paper outlines some of the issues related to that development, including an examination of the particular requirements of shipboard systems and how those requirements affect development of general purpose fiber optic based sensors. The tradeoffs between passive fiber optic transducers and equivalent self-powered electrical "active" devices using fiber optic signal lines are examined. Additionally, a basis for the development of these "active" sensors will be presented, along with descriptions of a non-contacting limit switch and linear position sensor equivalent in function to the LVDT (linear variable differential transformer).

This paper describes a program wherein fiber optic technology was introduced into the U. S. Navy's AEGIS Cruisers. This program was sponsored and funded for the most part by Naval Sea Systems Command and represents the first significant effort involving naval vessels. Although specific to one ship class, the program achievements are applicable to most naval as well as commercial ships. The process of transitioning fiber optic technology from the laboratory or commercial sector to a military ship is described. The issues addressed and problems resolved during this transition are discussed. Some of the primary issues include transmission data rates, ship producibility and environmental concerns such as temperature extremes, shock, vibration, ionizing radiation, toxic materials, etc. Additionally, the advantages of fiber optic technology specific to U. S. Naval ships are explained. Of particular importance are the developments that evolved from the AEGIS Cruiser program. Developments include a unique cable design, junction boxes, connectors, a splice, emergency repair procedures, a remote motor control system, a torsionmeter system, and a family of sensors and switches. The overall program resulted in the installation of fiber optic systems on three U. S. Navy ships. These installation projects are described along with some of the lessons learned. The paper concludes that the past issues that prevented the use of fiber optic technology in naval ships have been addressed and resolved. Fiber optics has successfully been introduced into naval combatants in data transmission, control, and sensing applications. Normal producibility has been considered such that fiber optic systems have been installed in almost routine fashion by a commercial shipyard. Additionally, human factor considerations have resulted in little or no additional training being required for operational and maintenance personnel.

Rockwell International Corporation's Expanded Service Shipboard Data Multiplex System (ES-SDMS) is a high-speed fiber-optic data transfer system suited for any Navy combatant that requires survivability, operational flexibility, noise immunity, and future growth potential. This state-of-the-art system replaces the point-to-point wiring required to interconnect systems and subsystems aboard ships. ES-SDMS accommodates most types of ship-board data transfers, including intercomputer, sensor, voice, and video signals. ES-SDMS is now in development for a number of shipboard applications.

Technology has stretched the imagination of the maritime industry evolving from pneumatics to analog electric to the microprocessor revolution. And today....fiber optics. Each technological step has faced the scrutiny of an industry reluctant to change for change's sake. This reluctance is bred not from stubbornness, but from experience with a force unrelenting and unforgiving....the SEA. This paper will evaluate the incorporation of fiber optic technology in the maritime industry from the standpoint of a communication link and a process sensor. The evaluation will consider issues surrounding fiber optics relative to current technological alternatives, implementation costs and environmental considerations. This paper will focus less on describing the fiber optic process and more on issues surrounding implementation, installation and potential. The purpose will not be to praise nor condemn fiber optics or currently used technology, rather it will attempt to point out objectively the functionality of each. This paper will be divided into three major sections, communications, sensor technology and potential applications. Within each section issues associated with implementation, installation and technology shall be discussed. In conclusion the final section shall address what the issues are for standards regarding fiber optics in the commercial maritime industry. For the purposes of this paper the maritime industry is defined as encompassing commercial surface shipping, offshore platforms, semi-submersibles and sub-sea applications and commercially classed US Navy vessels.

This paper describes environmental effects which impact the design of interfaces to fiber-optic sensors and data buses in aircraft engine controls. Emphasis is placed on selection of components and designs which maintain their performance and reliability in the harsh environment of an electronics enclosure mounted on a modern aircraft turbine engine. Particular attention is given to the effects of temperature on electro-optical component and system performance. The main conclusion is that electro-optical interfaces to a variety of fiber-optic systems can be installed in an engine-mounted control if the designs and components are selected after careful analysis of the effects of the engine environment.

Presently, there are three basic network topologies under serious consideration for use in aircraft data distribution systems. These are star networks, active rings, and linear busses. The greatest factor involved in the selection of a topology for a typical application has generally been the number of nodes which may be accessed by that topology. In that respect, active rings are able to utilize the greatest number of nodes, followed by star networks and finally linear topologies. Active rings have the advantage of requiring the minimal performance from the optical components (transmitters, receivers, couplers), but have two major drawbacks. First, each node functions as a repeater leading to degradation in the system bit error rate. Second, in order to eliminate single point failures complicated systems for bypassing nodes and counter rotation schemes must be used. Star networks require little dynamic range and offer potentially large numbers of nodes, but are also susceptible to single point failures. In addition, a large amount of cable is required in a star network, especially for redundant systems. Linear topologies offer a minimum of cabling for a passive system resulting in ease of installation and maintenance, but until recently have been ruled out for more than about ten nodes due to the additive nature of the power losses and the relatively high insertion loss of the optical taps. The development of low loss couplers with non-reciprocal coupling of optical power between tap fibers and bus fibers has allowed the consideration of linear topologies for much larger numbers of nodes. "Asymmetric" tap couplers provide the maximum amount of optical power to be launched onto the bus fiber while maintaining the low insertion loss and tapoff ratio necessary for accessing many nodes. These couplers essentially launch more power onto the bus than they tap out of the bus, while preserving their inherently low excess loss. In this paper, a description of the operation of the asymmetric coupler is given, along with test data indicating the important performance parameters. Additional test data is provided for a linear data bus configured from such couplers. The impact of linear topologies and various data transmission schemes on transmitter and receiver design will be addressed. Further discussions are presented regarding the environmental conditions which must be addressed for aircraft applications, and additional data are presented indicating actual performance of the linear data bus and its various components under those environmental conditions.

Two different architectures of high speed fiber optic links that can be used in place of coaxial or waveguide systems in various applications have been designed analyzed and experimentally evaluated. A comparison between these two configurations show that a substantial improvement in the system noise figure and dynamic range can be obtained by selecting the appropiate configuration.

The recent availability of ultra-fast laser diodes with matching fast photodetectors that can be directly modulated at radio frequencies (RF) offer an alternative interconnection technology in airborne systems. If these devices are used with optical fibers they can replace RF cables, because they can save substantially on weight and cost while providing superb Electromagnetic Interference (EMI), Electromagnetic Pulse (EMP), and TEMPEST performance. Preliminary measurements of the RF/microwave response of laser diodes and matching detector will be reported. The measurements include insertion loss, dynamic range, bandwidth, single tone harmonic generation, and two tone intermodulation products. Discussion of results will address the sensitivity of the laser diode/detector to modulation index and frequency. The optical subsystem will be examined over the frequency range 100 MHz to 10 GHz. A candidate Satellite Communication (SATCOM) terminal design will be discussed that uses the fiber optics to interconnect subsystems. Recommendations for combining RF and digital signals using RF and color multiplexing will be reported.

Present fiber optic cables and connectors have been designed to requirements that orig-inated in large part within the telecommunications industry. However, system requirements for mobile platforms (aircraft, ships and space vehicles) differ greatly from telecommunication requirements with respect to cable lengths, frequency of disconnect points and nature of the environment. In general, components have not been designed in concert with each other to achieve overall system goals. This has resulted in components that may be individually excellent but do not operate well together to meet reliability and maintainability needs of mobile platforms. This paper sets forth the most important system parameters associated with typical mobile platforms with particular emphasis placed on aircraft system needs. Based on these system parameters, an integrated set of termination characteristics is proposed.

The role of fiber optics on next-generation commercial aircraft is considered. The benefits and difficulties associated with fiber optics on aircraft are reviewed, as well as the most promising near-term fiber optic technologies for aircraft applications. An overview of the Fiber Optics Readiness Program at Douglas Aircraft Company is presented, and some likely fiber optic interfaces are given.

Spacecrafts planned for the years 1995-2000 are envisaged to contain a generic PAM (Propulsion Avionics Module) A part of the PAM has the task to process data form a large number of embedded sensors to perform control, diagnostics and health monitoring. These tasks include the following. --Control, for the real-time closed loop control of the craft during the mission. --Diagnostics, for fault isolation and corrective action initiation during the mission. --Health Monitoring, to assess after a mission, if the craft will fly again? What refurbishing is needed? To carry out the above tasks the PAM and the associated sensors should provide an integrated environment to perform three generic computational activities, namely, numeric manipulations for general data processing and data base management, symbolic manipulations for diagnostics and decision making, graphic presentation as an interface with operators in manned missions. Furthermore, the communication among the processors and the sensors should be EMI and hostile environment resistant. We have implemented a FO-LAN based testbed as an integrated environment of numerical, symbolic and graphic processors with ports for sensors and actuators. A multimode, 832 nm carrier wavelength, passive star network connects a Microvax, LMI LAMBDA (with PICON) and Silicon Graphics IRIS workstation. There are four additional ports for connecting sensors and actuators. With this testbed, we can evaluate various architectures can also carry out hardware in the loop simulations for studying control strategies. Details of the testbed and preliminary results of intelligence sensor analysis will be presented.

The persistent trend to use millimeter wave frequencies for satellite communications and surveillance presents the challenge to design large aperture phased array antennas for various space applications. These arrays, now under consideration, will comprise of thousands of elements utilizing monolithic microwave integrated circuit modules, and will have a fiberoptic distribution network. New space vehicles, such as the space station, will contain several remotely-located antennas which must be connected to central processing units. The interconnecting of these remotely-located antennas will be done via fiber-optic links. Therefore, the two most important applications of fiberoptic distribution networks in spacecraft are antenna remoting and phased array distribution networks. These will be considered in this paper.