Introduction

The evolution of increasingly complex shipboard control systems demands more and more sophisticated sensory inputs throughout the ship.  The number of sensors needed is likely to proliferate and be limited only by the cost of  the sensor systems.  The large number of sensory inputs needed to control and to monitor modern ships makes fiber-optic sensor (FOS) systems attractive to shipbuilders.  FOS systems on board ships can provide instantaneous and redundant sensor inputs to streamline ship operations.  Furthermore, they will make the ship safer by providing early hazard warnings and damage assessments that are the dominant safety concern for ship operators.

Background

It is well known that FOS systems can improve ship safety and automate ship operations.  In fact, the U. S. Navy has been an active participant in developing shipborne fiber-optic sensor for the last twenty years.

Compared to conventional sensor systems, FOS systems clearly have the advantages, including:

Accuracy

Compactness

Lightweight

Reliability

Low cost.

Chemically inert

Consume no power

Configured in different shapes as appropriate for the application

Immune to electromagnetic interference

Operate in harsh environments.

However, their applications in the marine instrumentation areas are still limited.  Although a number of fiber-optic communication systems are currently in service on board ships, incorporating FOSs into fiber- optic communication links is still difficult.  Many technical difficulties still need to be addressed.

Objectives

This work is to investigate the issues of implementing intrinsic FOS networks into modern ships.  There are three main obstacles for such an implementation: development cost, large scale FOS integration, and unproved track record.  The last one can be addressed through the prototyping and testing in GCRMTC and elsewhere so that FOS systems will eventually gain acceptance in the shipbuilding industries.  In this work, we focus on the issues of development cost and large scale FOS systems integration.

Applications

Thus, a FOS system may contain many individual sensors throughout a ship and feed the information to the control unit.   FOS systems have been devised for a vast range of measurements such as:

Fire, smoke, gas detection

Pressure and liquid level monitoring

Position, vibration, acceleration and rotation measurements

Instantaneous damage assessment and hazard warning

Development and Deployment Partners

Entergy Inc.

U.S. Naval Research Laboratory

Omni Technology

Ingalls Shipbuilders

U.S. Department of Energy

Tasks

1) Theoretical study of novel fiber-optic sensors
We have developed a novel Yee's mesh finite-difference vectorial-beam-propagation method, which has demonstrated to be an efficient, simple, and accurate method for sensor head analysis.

2)  Evanescent wave sensor using D-shape fibers
A novel fiber-optic evanescent-wave sensor has been demonstrated as an effective pollution monitor.  In collaboration with Entergy, these sensors are used as an insulator surface pollution monitor.  They are proven to be useful in-situ monitors in the high electromagnetic interference and high electrical insulation environments.

3)  Development and tests of an all fiber-optic in-line photopolarimeter
We have also demonstrated an all fiber-optic in-line photopolarimeter.  It is compact, inexpensive, and very useful for calibrating fiber optic polarimetric sensors.  A US Patent for this device has been filed.

4)  Fiber-Bragg-grating (FBG) sensors
Of all sensors on board a modern ship, upto 90% of them are either pressure or temperature sensors.The FBG strain sensors can be converted into temperature and pressure sensors by choosing the proper packaging and substrate materials. The center wavelengths of the reflection from each grating can be interrogated using either a tunable fiber-optic source or a wavelength selectable detector. Applying the wavelength- and time-division multiplexing principles, the number of sensors in one detecting system can proliferate into tens of thousands. Two novel large-scale FBG sensor system configurations based on wavelength and time-division multiplexing techniques have been demonstrated. We have improved the scanning speeds and number of grating sensors over existing FBG network configurations.
 

For more information contact:

Dr. Shing Lee
504-280-5460
E-Mail: smlee@uno.edu

GCRMTC TECHNICAL BRIEFS are published periodically by the Gulf Coast Region Maritime Technology Center, a U.S. Navy Center of Excellence in Advanced Marine Technology based at the University of New Orleans.  GCRMTC's Mission is to "enhance international competitiveness in the U.S. shipbuilding industry through sponsored research."   For additional information, contact:  GCRMTC, University of New Orleans, New Orleans, LA 70148, Tel: (504) 280-3871, Fax: (504) 280-3898, E-mail: jtsen@uno.edu

The contents of this publication reflect the views of the MERIC staff and are based on information obtained from the literature.  The contents do not necessarily reflect the official views or the policies of MERIC or the Gulf Coast Maritime Technology Center.  This publication does not constitute a standard, specification, or regulation.  MERIC does not endorse products, equipment or manufacturers.  Trademarks or manufacturer's names appear herein only because they are considered essential to the object of this publication.