Commercial and military ships of the next century will have many new capabilities not present today. These capabilities can be realized only after certain design needs or requirements have been satisfied by the shipbuilder. (The term shipbuilder includes ship designers and ship fabricators). The introduction of fiber optic technology may make it easier for the shipbuilder to meet these needs. Three important shipbuilding requirements are discussed together with one or more examples. Conventional approaches are contrasted with those utilizing fiber optic techniques. Fiber optics appears to satisfy these design needs. There are, however, a few issues that must be considered as these techniques are applied to ships. These issues are identified. The success of fiber optics on ship platforms will depend largely upon a cooperative exchange of information between the shipbuilder and the fiber optics community. Some suggested topics for this exchange are listed.
Today, it is reasonable to project the application of optical fibers aboard both commercial and military ships of the future. The reasonableness of such projection is clear from the fact that optical fibers have been and are being installed in a limited way in new and overhaul ship construction programs. Rationale for installation of optical fibers on ships derives from several well-known optical fiber characteristics: high bandwidth, no EMI, compactness, adverse environment compatibility, etc. It seems clear that such characteristics will be valuable on board ships. However, to amplify, future commercial ships will continue to demand operating cost reductions. This means more automation, smaller crews and, subsequently, more data transmission capacity. More automation and smaller crews also demand more remote sensors connected to control processors. Fiber sensors, if all other characteristics are at least equal to those of traditional sensors, are the best choice in conjunction with optical fiber transmission lines. Most often they require no power other than that for the optical data signal and they require no local amplification, both features avoiding complexity and reliability problems. The same arguments apply to military ships as well. However, military ships are not driven so strongly by cost considerations. One concept of a future military ship envisions a stealthy, highly automated, cruise missile launching platform. Such a ship can be minimally manned, but must, therefore, be a highly reliable, low main-tenance and, consequently, highly sensor- and telemetry-redundant ship. The obvious answer is optical fiber telemetry and fiber optic sensors. In this paper we will review the status of several of the prominent elements facilitating shipboard fiber optic systems. In addition, known problems of shipboard applications will be noted and subsequent challenges, thus opportunities, will be presented to the fiber optics commmunity.
The generation of a Department of Defense specification or standard requires time consuming steps to ensure that all interested activities within the military and industry have an opportunity to contribute to the development of the document. This paper addresses the reasons for the time required to issue a standardization document, ways to accelerate the standardization process without violating the procedures, as well as a planned computerized system to speed document coordination.
The military is developing standards to define new communications systems and protocols based on fiber optic Local Area Networks (LANs). This paper describes the work of the Survivable Adaptable Fiber Optic Embedded Network (SAFENET) Committee and its approach to network development It covers the criteria established for selection of a fiber optic LAN and the family of LANs selected by those criteria.
In 1984 General Regulator, formally a division of Forney Engineering, successfully installed the first centralized engine room monitoring system using a fiber optic data link onboard a commercial ship. In 1986 a paper by Richard M. Lewis of Forney Engineering was presented to the SAE describing this application and the fundamentals of fiber optic technology. Today General Regulator is a division of TANO Marine Systems. These companies are investigating new fiber optic applications onboard commercial and military ships. This paper describes the design and performance of the original system and the success and reliability of this approach. In addition, this paper explores other applications and future possibilities of fiber optics in control and monitoring systems onboard military and commercial marine vessels. The timely release of fiber optic component and systems specifications by the Naval Sea Systems Command should provide for an increased level of fiber optic system development and applications in the near future.
The U. S. Navy has determined a need for a new approach to data transfer during various shipboard tests. The approach will be based upon a fiber optic cable system for several reasons; large bandwidth, immunity to electromagnetic interference, and light weight in contrast to a comparable copper cable system. The Navy currently runs many tests on new ships before they are placed in unrestricted service. These tests range in scale and include tests on the propulsion system, electrical systems, and structural components in sometimes rugged environments. These tests are conducted by several Navy organizations and each test team must hard wire all sensors, recording equipment, communication lines, etc., independent of any permanent ship system. This requires a great amount of time and materials each time a test is conducted. A fiber optic cable system that can be installed once during construction of the ship that is flexible and capable of accommodating all types of data is proposed. Since this system is permanent it must have minimum impact on current ship designs. The final system plan, along with design requirements and performance analysis will be presented.
The Navy has been involved in the exploitation of fiber optics over the decade for which many of the developmental efforts have represented a significant breakthrough in technology and also for applications. Significant among the Navy initiatives has been the effort of the AEGIS Program Office of the Naval Sea Systems Command located in Washington D.C. This paper presents some of these developmental efforts coming out of initiatives. The efforts lead to the implementation of some demonstrations aboard the AEGIS Cruisers for shipboard evaluation purposes. The program objectives were met and the efforts were considered successful demonstrations of the performance of fiber optics aboard a Navy ship.
In late 1987, a fiber optic link demonstration was conducted on USS Nimitz (CVN-68) as part of a CNO task to develop standards and specifications for shipboard applications of fiber optics. The demonstration was sponsored by the Naval Sea Systems Command Fiber Optics Program Office (NAVSEA 56ZC) and implemented by the Naval Sea Systems Command Surveillance Systems Subgroup (NAVSEA 62X). The Johns Hopkins University / Applied Physics Laboratory (JHU/APL) was tasked by NAVSEA 62X to serve as principal technical agent for the demonstration. The objective of the project was to demonstrate the practical application of fiber optic technology in a shipboard environment, and to draw lessons applicable to the development of fiber optic standards for shipboard use.
This paper describes a new type of optical control panel that eliminates any electrical contacts and mechanically moving parts. It has potential for low cost, improved reliability, and diagnosability. In its simplest form, the control panel consists of an optically lossy plastic strip that is illuminated from the back side, and that runs parallel to a segmented screen on the front side. Each of the backlit segments acts as a switch. Normally all switches are in the OFF mode. OFF to ON switching is obtained by bringing a finger or reflector close to a segment so as to reflect and couple light into the strip. The back-coupled light divides into two guided waves that attenuate as they propagate towards the extremities of the strip. Two photodetectors detect these attenuated signals. Switch position is inferred from the ratio of the two detected signals. Three early prototypes were tested, each consisting of seven 5 by 15 millimeter switching segments. In all three cases, switch position was inferred without any ambiguity. This type of optical control panel is easy to incorporate in a display.
A fiber optic binary position sensor has been fabricated simply and inexpensively. This sensor exploits the Faraday Effect to detect the presence of a piece of ferrrous metal The sensor is positioned inside a ring magnet, so that when a ferrous metal object passes close to the face of the magnet, it distorts the field, changing the output of the sensor from low optical power to high. The key component is a piece of bismuth doped iron garnet film with an extremely high Faraday Rotation per unit length and a low saturation magnetization. Material properties of this film will be discussed, along with sensor design and performance. This sensor has many potential applications in the automotive industry, such as monitoring door, hood and trunk positions.
Fiber optic networks in the telecommunications and Local Area Network (LAN) applications are typically active networks (point to point fiber optic links interconnected using active devices). Short distance automotive networks have a sufficient flux budget to allow passive optical distribution. This paper reviews the differences between Telecommunications, LAN, and automotive network applications. The benefits of a passive star architecture will be described and a passive star implementation, based on large diameter plastic fibers, will be described.
A Mach-Zehnder type optical fiber sensor for measuring gas pressure of cylinder of car with special designed sensor box is reported.Experimental data show that it is an useful sensor for real-time operation.
This paper describes a design for fiber-optic sensing and control in advanced aircraft Electronic Engine Control (EEC). The recommended architecture is an on-engine EEC which contains electro-optic interface circuits for fiber-optic sensors. Size and weight are reduced by multiplexing arrays of functionally similar sensors on a pairs of optical fibers to common electro-optical interfaces. The architecture contains interfaces to seven sensor groups. Nine distinct fiber-optic sensor types were found to provide the sensing functions. Analysis revealed no strong discriminator (except reliability of laser diodes and remote electronics) on which to base a selection of preferred common interface type. A hardware test program is recommended to assess the relative maturity of the technologies and to determine real performance in the engine environment.
Advantages of fiber optic technology in an aircraft control system are realized at the system level and not in sensors or components themselves. Improved system reliability and performance, and reduced electro-optic (e-o) interface size, weight and cost may be realized with the use of fiber optic technology. This paper provides a discussion on the Electro-optic Architecture conceptual designs, sensor multiplexing approaches and key design requirements for the control system of the aircraft. In addition, a comparison of Time and Wavelength division multiplexed systems (TDM and WDM) for digital position sensors configured into a network is made to identify which approach meets system design criteria more efficiently. It is concluded that present WDM sensor interrogation time must be drastically reduced to be compatible with the aircraft control system and that both approaches require a highly reliable optical source which provides adequate power and spectral bandwidth.
We have been exploring the feasiblity of a power by light headset. The research has focused on defining a system concept which optimizes the uplink and headset "power by light" elements and minimizes the electrical power consumption of the microphone and downlink. We have identified a suitable system concept, and it has been supported by experiments performed on breadboards, as reported in a companion paper.
This paper describes the design and performance of a rotary position sensor system based on the principle of wavelength division multiplexing. The system is discussed in relation to the requirements on the source, sensor and detection circuits. Measured performance of the various components is presented for environmental conditions typical of various application areas within the aircraft. The wavelength sensing technique becomes the basis for an electro-optic architecture capable of multiplexing several sensors onto one common interface.
After 20 years of government, industry, and university research and development efforts, the reality of fly-by-light production aircraft is within sight. An overview is presented of the driving factors which make fly-by-light systems viable, and the philosophy and contributions of Douglas Aircraft Company are reviewed.
Fiber Optic Sensor technology has reached a point where it is now a major factor in the design of the next generation of Inertial Measurement Units (IMU). Because of the Fiber Optic Sensors unique characteristics, the next generation of IM Us will offer lower cost, large dynamic range, precision, flexibility of design, and affordable fault tolerant system design. This article will cover the • Unique system characteristics of Fiber Optic Gyros • Design considerations that govern the introduction of Fiber Optic Gyros in mobile platforms • Application of Fiber Optic Gyros to two unique mobile platform applications.
The next generation of flight control computers will utilize fiber optic technology to produce a fly-by-light flight control system. Optical transducers and optical fibers will take the place of electrical position transducers and wires, torsion bars, bell cranks, and cables. Applications for this fly-by-light technology include space launch vehicles, upperstages, space-craft, and commercial/military aircraft. Optical fibers are lighter than mechanical transmission media and unlike conven-tional wire transmissions are not susceptible to electromagnetic interference (EMI) and high energy emission sources. This paper will give an overview of a fault tolerant In-Line Monitored optical flight control system being developed at Boeing Aerospace & Electronics in Seattle, Washington. This system uses passive transducers with fiber optic interconnections which hold promises to virtually eliminate EMI threats to flight control system performance and flight safety and also provide significant weight savings. The main emphasis of this paper will be the In-Line Monitored architecture of the optical transducer system required for use in a fault tolerant flight control system.
Next generation digital flight control systems will require optical fiber technology to gain immunity to electromagnetic interference. A family of optically powered sensors currently in development and production will provide rugged, cost-effective alternatives for a variety of flight control and instrumentation needs.
Concepts of infrared fiber-optic (IFO) sensors were investigated for application as distributed fire sensors for Space Station Freedom. Testing of breadboard configurations (based on those concepts) showed that IFO fire-sensors will be able to detect fires in complex spacecraft with a network of lightweight fibers interfaced to a central detector. Fiber-multiplex configurations are preferred for large areas or modules, while small spacecraft compartments can be monitored with fiber configurations that are not location-sensitive with respect to individual fibers. Single-fiber (250 to 300-gm diameter) responsivity measurements conducted with reflective and refractive optical configurations for the central detector system indicated background-limited-ranges (BLR) of 2 to 3 m for early sensing of hydrocarbon and hydrogen flames (area of approximately 3 cm2). Signal processing techniques were also investigated, and the results showed significant differences in the fire sensor performance depending on the method of optically chopping the radiation signals. The single fiber BLR could be extended to 8 m by optically chopping the signals at the fiber input (as opposed to 2 to 3 m when chopping at the fiber output) for the flames tested. The results of the research work showed that IFO fire-sensors are feasible for application on Space Station Freedom; however, additional development work will be required to eliminate false alarms caused by high temperature objects if the sensors are to be used in other applications. Technology associated with acoustic-optic-tunable-filter (AOTF) spectrometers offers a potential method of solving this problem.