1、_ SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report is entirely voluntary, and its applicability and suitability for any particular use, including any patent infringement arising there
2、from, is the sole responsibility of the user.” SAE reviews each technical report at least every five years at which time it may be revised, reaffirmed, stabilized, or cancelled. SAE invites your written comments and suggestions. Copyright 2015 SAE International All rights reserved. No part of this p
3、ublication may be reproduced, stored in a retrieval system or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of SAE. TO PLACE A DOCUMENT ORDER: Tel: 877-606-7323 (inside USA and Canada) Tel: +1 724-776-497
4、0 (outside USA) Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.org SAE values your input. To provide feedback on this Technical Report, please visit http:/www.sae.org/technical/standards/AIR6258 AEROSPACE INFORMATION REPORT AIR6258 Issued 2015-06 Fiber Optic Sensors f
5、or Aerospace Applications RATIONALE The purpose of this document is to aid in sensor system selection for aerospace applications. It describes both generic and specific qualities of key fiber optic sensing technologies and the range of measurement tasks they are able to perform. This includes: A cri
6、tical and comprehensive comparison between specific optical sensor technologies, currently available, and corresponding non-optical sensing methods. This will assist aircraft component and subsystem designers to assess their suitability and potential for specific applications. An appraisal of techno
7、logy maturity levels and technology gaps. Guidelines on the use and application of classes of fiber optic sensors are given including: o sensor and system compatibility (including fiber cable, connectors, interrogator, signal conditioning, network interface, and power requirements), o compatibility
8、with aircraft systems, o standard forms of interrogation/interface, o proposed methods of standardization, and o qualification recommendations. SAE INTERNATIONAL AIR6258 Page 2 of 112 TABLE OF CONTENTS 1. SCOPE 8 2. APPLICABLE DOCUMENTS 8 2.1 SAE Publications . 8 2.2 U.S. Government Publications 9 2
9、.3 Other Documents 9 2.4 References 9 2.5 Definitions . 14 2.5.1 Acronyms 14 2.5.2 General Definitions 16 3. LASER SAFETY . 18 3.1 General 18 3.2 Eye Hazards 18 3.3 Laser Classification . 19 4. INTRODUCTION TO FIBER OPTIC BASIC THEORY . 21 4.1 Optical Fiber 21 4.1.1 Propagation of Light 21 4.1.2 Opt
10、ical Fiber Cable . 23 4.1.3 Fiber Characteristics . 23 4.2 Fiber Optic System Active Components . 25 4.2.1 Sources . 25 4.2.2 Photodetectors Semiconductor Detectors . 26 4.2.3 Front-End Amplifier . 27 4.2.4 Spatial Detector . 28 4.2.5 Diplexers . 28 4.2.6 Integrated Devices 28 4.3 Fiber Optic Cables
11、 and Connectors 28 4.4 Photonic Crystal Fiber . 36 5. FIBER OPTIC SENSORS AND APPLICATIONS . 37 5.1 Fiber Optic Sensing Technologies 37 5.1.1 Advantages of Fiber Optic Sensors 38 5.2 Intensity Modulated Sensors . 39 5.2.1 Variable Reflection 39 5.2.2 Light Shutter or Variable Coupling 39 5.2.3 Stres
12、s-Induced Birefringence 40 5.2.4 Magneto-Optic Effect 44 5.2.5 Variable Light Loss through a Dielectric Interface 44 5.2.6 Point Level Sensors 45 5.2.7 Frustrated Total Internal Reflection . 45 5.2.8 Intensity Modulated Sensor Pros and Cons 46 5.3 Interferometric (Phase Modulated) Fiber Sensors 47 5
13、.3.1 Mach-Zehnder Interferometer . 47 5.3.2 Michelson Interferometer 48 5.3.3 Fabry- Prot interferometer . 49 5.3.4 Sagnac Interferometer 54 5.3.5 Fizeau Interferometer 55 5.3.6 Compact Mach-Zehnder and Michelson Interferometric Sensor Architectures 56 5.4 Grating Fiber Optic Sensors . 57 5.4.1 Gene
14、ral 57 5.4.2 Strain and Temperature Masurement . 58 5.4.3 Grating Writing Process 59 5.4.4 Types of Gratings 59 5.4.5 Aerospace Applications. 61 5.4.6 Long Period Gratings 62 5.5 Spectroscopic Fiber Sensor 63 5.5.1 Fiber Optic Evanescent Wave Spectroscopic Sensor 63 SAE INTERNATIONAL AIR6258 Page 3
15、of 112 5.6 Fiber Bending-Actuated Sensors 64 5.7 Polarimetric Fiber Optic Sensors 65 5.8 Distributed Fiber Optic Sensors 66 5.8.1 Distributed Fiber Optic Sensors 66 5.8.2 Quasi-Distributed Fiber Optic Sensors . 67 5.9 Optically Powered Sensors . 68 5.9.1 Philosophy of the Optically Powered Sensor 68
16、 5.9.2 The Photovoltaic Converter 68 5.9.3 Limitations of the Power over Fiber System . 69 6. INTERROGATORS . 70 6.1 Fabry-Perot Cavity Interrogators . 70 6.1.1 Introduction . 70 6.1.2 Basic Principle . 70 6.1.3 Technical Description 70 6.2 Edge Filter Detection . 73 6.3 Polarization Based Interroga
17、tors . 74 6.3.1 Interrogators for Interferometric Sensors 74 6.3.2 Interrogators to Complement Polarization Dependent Sensors . 75 6.4 Multi-Point Sensor Interrogators . 77 6.4.1 Broadband Source and Spectrometer 77 6.4.2 Tunable Lasers . 78 6.5 Intensity Modulated Interrogators . 78 6.5.1 Analog .
18、79 6.5.2 Pulse-Counting (Digital or Time-Domain) . 81 6.6 Distributed Fiber Optic Sensor Interrogators 81 6.6.1 Distributed Sensing via OFDR 82 6.6.2 Distributed Sensing via OTDR 83 6.6.3 Quasi-Distributed Sensing via WDM . 83 6.7 Optical Backscattering Reflectometry . 83 6.7.1 Multipoint and Distri
19、buted Sensing with FBGs or Rayleigh Scatter 84 6.7.2 Comparison of OTDR, WDM, OFDR and OBR Interrogators . 85 6.8 Pyrometry/Spectrometry . 86 7. FIBER OPTIC SENSOR APPLICATION 88 7.1 Physical Parameter Sensing . 88 7.2 Chemical Sensing . 89 7.3 Health Monitoring 91 7.4 High Temperature Optical Sensi
20、ng . 92 7.4.1 Introduction . 92 7.4.2 Optical Fibers for High Temperatures . 92 7.4.3 Fiber Bragg Grating (FBG) Sensors at High Temperatures . 93 7.4.4 Fabry-Perot (FP) Sensors . 98 7.4.5 Other Fiber Optic Sensors at High Temperatures 98 7.4.6 Luminescence Time Decay Sensing . 99 7.5 Space Applicati
21、ons 101 8. REQUIREMENTS . 104 8.1 Performance 104 8.1.1 Power Budget 104 8.1.2 Calibration Interchangeability/Redundancy/Fault Tolerance/Self-Test . 104 8.2 Interface 104 8.3 Environmental Conditions . 105 8.3.1 Environmental Qualification Considerations . 107 8.4 Reliability of Systems 108 8.5 Main
22、tenance 108 9. TRENDS . 109 10. NOTES 109 SAE INTERNATIONAL AIR6258 Page 4 of 112 APPENDIX A EXAMPLES OF SOME TEST REQUIREMENTS APPLIED TO AEROSPACE COMPONENTS AND EQUIPMENT 110 FIGURE 1 EYE STRUCTURE AND TRANSMISSION PATH OF LIGHT 19 FIGURE 2 TOTAL INTERNAL REFLECTION 21 FIGURE 3 SNELLS LAW . 22 FI
23、GURE 4 LIGHT PROPAGATION AND NUMERICAL APERTURE 22 FIGURE 5 ACCEPTANCE CONE 22 FIGURE 6 TYPICAL FIBER OPTIC CABLE . 23 FIGURE 7 LIGHT PROPAGATION IN COMMON TYPES OF FIBER . 24 FIGURE 8 TYPICAL ATTENUATION OF A SILICA FIBER AS A FUNCTION OF WAVELENGTH 25 FIGURE 9 TRANSIMPEDANCE AMPLIFIER CIRCUIT . 27
24、 FIGURE 10 SCHEMATIC DIAGRAM OF PHYSICAL CONTACT FIBER INTERCONNECTION 30 FIGURE 11 SCHEMATIC DIAGRAM OF A LENSED EXPANDED BEAM INTERCONNECTION 31 FIGURE 12 EXAMPLES OF MIL-PRF-29504 FIBER OPTIC TERMINI AND MIL-DTL-38999 SERIES III CONNECTORS COURTESY OF DEUTSCH . 32 FIGURE 13 EXAMPLES OF ARINC 801
25、(EN 4644) RECTANGULAR CONNECTORS COURTESY OF DEUTSCH 32 FIGURE 14 EXAMPLES OF EN 3733 CONNECTORS . 33 FIGURE 15 EXAMPLES OFEN 4531 CIRCULAR CONNECTOR WITH EN 4531-101 CONTACTS (ARINC 801 ANNEX C) COURTESY OF DEUTSCH . 33 FIGURE 16 EXAMPLES OF CIRCULAR, SINGLEWAY AND MULTIAY CONNECTORS COURTESY OF DE
26、UTSCH 34 FIGURE 17 EXAMPLES OF RUGGEDIZED SINGLEWAY CONNECTOR COURTESY OF DEUTSCH . 34 FIGURE 18 EXAMPLES OF RUGGEDIZED SINGLEWAY EXPANDED BEAM CONNECTOR COURTESY OF DEUTSCH 34 FIGURE 19 EXAMPLES OF EN 4165 COMPLIANT MODULAR CONNECTOR COURTESY OF DEUTSCH 35 FIGURE 20 AVIM CONNECTOR AND ADAPTER COURT
27、ESY OF DIAMOND USA INC. 35 FIGURE 21 CABLE TERMINATED STANDARD AVIM DISCONNECTED FROM AVIM CLEANABLE ADAPTAER (TOP) AND FIBER TERMINATED MINI-AVIM DISCONNECTED FROM ADAPTER (BOTTOM) COURTESY OF DIAMOND USA INC. 35 FIGURE 22 EXAMPLES OF SOLID CORE PHOTONIC CRYSTAL FIBER 36 FIGURE 23 DIAGRAM OF A SOLI
28、D CORE PCF PREFORM STACK AND FIBER DRAW, A) PCF PREFORM IS CREATED BY STACKING GLASS RODS, B) PCF PREFORM IS DRAWN IN A FIBER DRAW TOWER, C) PARTIALLY DRAWN PCF PREFORM ( 2012 IEEE) 4.4.4 . 36 FIGURE 24 (A) TEMPERATURE DEPENDENCE OF CONVENTIONAL PM FIBER AND PM-PCF CONFIGURED AS A SAGNAC INTERFEROME
29、TER, (B) CROSS SECTION OF THE COMMERCIALLY AVAILABLE PURE SILICA PM-PCF USED IN THE EXPERIMENTATION 4.4.6 . 37 FIGURE 25 SCHEMATIC DIAGRAM OF VARIABLE COUPLING FIBER OPTIC SENSOR 6.8.1 . 39 FIGURE 26 SCHEMATIC DIAGRAM OF STRESS-INDUCED BIREFRINGENCE SENSING 6.8.1 . 40 FIGURE 27 SCHEMATIC DIAGRAM OF
30、A PHOTOELASTIC PRESSURE SENSOR 6.8.1 41 FIGURE 28 SINE SQUARED INTENSITY MODULATION FUNCTION OF A STRESS-OPTIC SENSOR AT VARIOUS TEMPERATURES 6.8.1 41 FIGURE 29 OUTPUT OF A HIGH PRESSURE PHOTOELASTIC SENSOR SHOWING THE QUADRATURE POINT AND LINEAR RANGE 6.8.1 42 FIGURE 30 INTENSITY MODULATED FIBER OP
31、TIC PRESSURE SENSOR 6.8.1 43 FIGURE 31 INTENSITY MODULATED RESPONSE OF A PHOTOELASTIC DRAG FLOWMETER 6.8.1 . 43 FIGURE 32 FIBER OPTIC POINT LEVEL SENSOR 6.8.1 45 FIGURE 33 MACH-ZEHNDER INTERFEROMETER DESCRIBED IN FREE SPACE AND FIBER OPTIC VERSIONS 47 FIGURE 34 MICHELSON INTERFEROMETER DESCRIBED IN
32、FREE SPACE AND OPTICAL FIBER VERSIONS 48 FIGURE 35 FABRY- PROT INTERFEROMETER DESCRIBED IN FREE SPACE AND FIBER OPTIC VERSIONS 49 FIGURE 36 NOMINAL REFLECTED RESPONSE FROM A FABRY-PEROT SENSOR A) INTERROGATED AT ONE WAVELENGTH AND B) INTERROGATED AT TWO WAVELENGTHS 50 FIGURE 37 INTRINSIC FABRY-PEROT
33、 INTERFEROMETRIC SENSOR CONFIGURATIONS (A) WITH IN-LINE MIRRORS (B) WITH IN-LINE FBG REFLECTORS . 51 SAE INTERNATIONAL AIR6258 Page 5 of 112 FIGURE 38 (A) TEMPERATURE AND (B) STRAIN RESPONSE OF (C) AN IFPI SENSOR MADE FROM FUSION SPLICED SMF AND MMF ( 2005 IEEE) 5.3.4 51 FIGURE 39 SELECTED CONFIGURA
34、TIONS OF EXTRINSIC FABRY-PEROT INTERFEROMETRIC SENSORS . 52 FIGURE 40 (A) DIAGRAM OF AN EPOXY-LESS EFPI SENSOR (B) THE SENSOR BEFORE AND AFTER FINAL PACKAGING 5.3.5 52 FIGURE 41 (A) PRESSURE SENSOR INSTALLATION IN TURBINE AND (B) ILLUSTRATION 5.3.5 . 53 FIGURE 42 (A) TIME AND (B) FREQUENCY DOMAIN RE
35、SPONSES OF AN EFPI FIBER OPTIC SENSOR AND A COMMERCIALLY AVAILABLE ELECTRICAL SENSOR 5.3.5 53 FIGURE 43 SAGNAC INTERFEROMETER DESCRIBED IN FREE SPACE AND FIBER OPTIC VERSIONS 54 FIGURE 44 COMMERCIALLY AVAILABLE FIBER OPTIC GYROSCOPE COURTESY OF KVH INDUSTRIES, INC. 54 FIGURE 45 FIZEAU INTERFEROMETER
36、 DESCRIBED IN FREE SPACE AND A DIAGRAM OF A COMMERCIALLY AVAILABLE FIBER OPTIC DISPLACEMENT SENSOR COURTESY OF FISO TECHNOLOGIES, INC. 55 FIGURE 46 (A) SCANNING ELECTRON MICROSCOPE IMAGE OF A SILICON DIOXIDE CANTILEVER, (B) FIZEAU INTERFEROMETER FRINGE PATTERNS, (C) CONTOUR PLOT, (D) CALCULATED STRE
37、SS DISTRIBUTION, WHERE LIGHTEST AREA INDICATES HIGHEST STRESS 5.3.7 55 FIGURE 47 CONFIGURATION OF VARIOUS COMPACT MZIS: (A) LPGS, (B) CORE MISMATCH, (C) AIR-HOLE COLLAPSED PCF, (D) MMF, (E) SMALL CORE SMF, (F) FIBER TAPERS 5.3.8 . 56 FIGURE 48 CONFIGURATION OF VARIOUS COMPACT MIS: (A) AIR-HOLE COLLA
38、PSED PCF AND (B) LPG 5.3.8 56 FIGURE 49 OPTICAL FUNCTION OF A BRAGG GRATING 5.4.1 . 57 FIGURE 50 (A) EXAMPLE OF A ROBUST AND FLEXIBLE STRAIN AND TEMPERATURE SENSOR PATCH FOR SURFACE MOUNT (B) A WELDABLE FIBER OPTIC STRAIN SENSOR FOR METALLIC STRUCTURES 5.4.2 . 58 FIGURE 51 FIBER BRAGG GRATING SCHEMA
39、TIC 5.4.4 . 59 FIGURE 52 A SCHEMATIC DIAGRAM OF THE (A) COMMON FIBER BRAGG GRATING, (B) BLAZED GRATING, AND (C) CHIRPED GRATING WITH AN APERIODIC PITCH 5.4.4 . 61 FIGURE 53 REPRESENTATIVE SPECTRUM OF A LONG PERIOD GRATING . 62 FIGURE 54 TEMPERATURE RESPONSE OF A LONG PERIOD GRATING WRITTEN WITH A PI
40、TCH OF 240 MICROMETERS INTO THE CORE OF A BORON AND GERMANIUM CO-DOPED SINGLE MODE FIBER ( 2001 IEEE) 5.4.13 63 FIGURE 55 (A) RAY DIAGRAM OF PROPAGATING RADIATION AND PENETRATION DEPTH: DP IS NOT TO SCALE, (B) SAMPLE OF ABSORPTION SPECTRUM 63 FIGURE 56 MACROBENDING FIBER OPTIC SENSOR 6.8.1 . 65 FIGU
41、RE 57 POLARIMETRIC FIBER OPTIC SENSOR DIAGRAM . 66 FIGURE 58 THREE CONSECUTIVE RETURN LOSS VERSUS DISTANCE MEASUREMENTS OF THE RAYLEIGH BACKSCATTER OF A SEGMENT OF SINGLE MODE FIBER AS MEASURED WITH A COMMERCIAL OFDR INTERROGATOR COURTESY OF LUNA, INC. . 66 FIGURE 59 AN EXAMPLE OF RETURN LOSS VERSUS
42、 LENGTH MEASUREMENT OF A SEGMENT OF A QUASI-DISTRIBUTED FIBER OPTIC SENSOR COURTESY OF LUNA, INC. . 67 FIGURE 60 SCHEMATIC OF THE OPTICALLY POWERED SENSOR 68 FIGURE 61 TYPICAL I-V CURVE OF A PHOTOVOLTAIC CONVERTER FOR A CONSTANT OPTICAL POWER ILLUMINATION 69 FIGURE 62 OPTICAL SCHEMATIC OF INTERROGAT
43、OR 70 FIGURE 63 SPECTRAL RESPONSE OF AN FP CAVITY FOR A GIVEN CAVITY LENGTH 71 FIGURE 64 MULTI - CAVITY REFLECTION SPECTRUM 72 FIGURE 65 RECEIVED INTENSITY VERSUS INTERROGATOR CAVITY LENGTH 72 FIGURE 66 SCHEMATIC DIAGRAM OF BROADBAND SOURCE USED TO MEASURE FBG SENSOR- INDUCED SHIFT IN THE REFLECTED
44、WAVELENGTH . 74 FIGURE 67 POLARIZATION BASED INTERROGATOR 75 FIGURE 68 POLARIZATION DEPENDENT SENSOR INTERROGATOR EXAMPLE SCHEMATIC . 76 FIGURE 69 MULTIPLE FBG SENSOR INTERROGATION USING A BROADBAND SOURCE AND SPECTROMETER, WHERE EACH FBG REFLECTS AT A DIFFERENT WAVELENGTH . 77 FIGURE 70 USE OF A TU
45、NABLE LASER AND TIME MULTIPLEXING TO INTERROGATE FBG SENSORS, WHERE EACH FBG REFLECTS AT A DIFFERENT WAVELENGTH . 78 SAE INTERNATIONAL AIR6258 Page 6 of 112 FIGURE 71 CONCEPTUAL DIAGRAM OF BASIC INTENSITY MODULATED INTERROGATOR 79 FIGURE 72 SCHEMATIC DIAGRAM OF INTENSITY MODULATED SENSOR NETWORK 6.8
46、.1 80 FIGURE 73 TWO-WAVELENGTH SELF-CALIBRATION APPLIED TO A NETWORK OF INTENSITY- MODULATED SENSORS 6.8.1 81 FIGURE 74 BASIC OFDR INTERROGATION NETWORK 82 FIGURE 75 BASIC OTDR INTERROGATION NETWORK 83 FIGURE 76 SAMPLE TIME DOMAIN DATA USING OPTICAL BACKSCATTER REFLECTOMETRY COURTESY OF LUNA, INC. 6
47、.7.2 . 84 FIGURE 77 TOP: SEVERAL (-65 DB) FIBER BRAGG GRATINGS WRITTEN AT THE SAME NOMINAL WAVELENGTH, 5 MM LENGTH AND SPACING, MEASURED USING OBR. BOTTOM: OBSERVED SPECTRAL SHIFT OF HIGHLIGHTED FIBER BRAGG GRATING. BLUE TRACE IS UNSTRAINED, RED STRAINED COURTESY OF LUNA, INC. . 84 FIGURE 78 TOP: RE
48、FLECTED SPECTRUM FROM A SEGMENT OF FIBER TAKEN WITH OBR RAYLEIGH BACKSCATTER MEASUREMENT. SOLID IS REFERENCE STATE, DOTTED IS HEATED BY 46 C COURTESY OF LUNA, INC. 85 FIGURE 79 EXAMPLES OF BLACK BODY RADIATION SPECTRA AT VARIOUS HIGH TEMPERATURES 6.8.1 87 FIGURE 80 EXAMPLE OF A FIBER OPTIC TWO-WAVEL
49、ENGTH PYROMETRIC SENSOR FOR TURBINE ENGINES 6.8.1 . 87 FIGURE 81 DIAGRAM OF A FULL SPECTRUM FIBER OPTIC SPECTROMETER COURTESY OF OCEAN OPTICS 88 FIGURE 82 SCHEMATIC EXAMPLES OF EXTRINSIC AND INTRINSIC CHEMICAL SENSING FIBER OPTIC SENSORS 6.8.1 89 FIGURE 83 CHEMICAL SENSING FIBER OPTIC OPTODE 7.2.2 . 90 FIGURE 84 FIBER REFRACT
