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 2012 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/AIR6031 AEROSPACE INFORMATION REPORT AIR6031 Issued 2012-08 Fiber Optic Cleaning
5、RATIONALE Cleaning is crucial to achieve and maintain the best possible operation of any optical fiber based application. Far too many failures are caused by poor or improper cleaning. Contamination of contact endfaces can lead to decreased system performance and damage to the optical fiber or ferru
6、le. 1. SCOPE This document is intended for connectors typically found on aerospace platforms and ground support equipment. The document provides the reasons for proper fiber optic cleaning, an in-depth discussion of available cleaning methods, materials, packaging, safety, and environmental concerns
7、. Applicable personnel include: Managers Designers Engineers Technicians Trainers/Instructors Third Party Maintenance Agencies Quality Personnel Purchasing Shipping/Receiving Production 2. APPLICABLE DOCUMENTS The following publications form a part of this document to the extent specified herein. Th
8、e latest issue of SAE publications shall apply. The applicable issue of other publications shall be the issue in effect on the date of the purchase order. In the event of conflict between the text of this document and references cited herein, the text of this document takes precedence. Nothing in th
9、is document, however, supersedes applicable laws and regulations unless a specific exemption has been obtained. 2.1 ANSI Publications Available from American National Standards Institute, 25 West 43rd Street, New York, NY 10036-8002, Tel: 212-642-4900, www.ansi.org. ANSI Z136.1-2007 American Nationa
10、l Standard for Safe Use of Lasers ANSI Z136.2-1997 American National Standard for the Safe Use of Optical Fiber Communication Systems Utilizing Laser Diode and LED Sources SAE AIR6031 Page 2 of 18 2.2 IEC Publications Available from International Electrotechnical Commission, 3, rue de Varembe, P.O.
11、Box 131, 1211 Geneva 20, Switzerland, Tel: +44-22-919-02-11, www.iec.ch. IEC 60825-1 Laser Safety Equipment Classification (Safety of laser products) IEC 60825-2 Safety of Optical Fibre Communication Systems IEC 60825-4 Laser Guards 3. SAFETY It is the responsibility of every employer to preserve, s
12、o far as is reasonably practicable, the health, safety and welfare of all employees. Common hazards often include chemical, optical power, fiber fragments, environmental, explosive, and personnel. Employers should ensure material safety data sheets (MSDS), first aid kits and eye wash stations are av
13、ailable in all areas where fiber optic work is being conducted. Fume hoods should be utilized where applicable. General awareness of working around aircraft and other potentially explosive environments is a consideration when utilizing any arc fusion splicers, curing ovens, ultrasonic cleaners or ot
14、her electrical or electronic devices. In addition, all employees have a duty of care to their work colleagues. It is the responsibility of every employee while at work to take reasonable care for his/her own health and safety and of other persons who may be affected by his acts or omissions at work
15、with regard to: 3.1 Handling Care should be taken when handling fibers. Flying glass fragments are often the result of cutting and cleaving operations and often go unnoticed. Glass fibers are small enough to puncture the skin and can remain under the skin surface. Besides being an irritant, fragment
16、s of glass fibers are not easily seen and can be difficult to remove. It is particularly important to prevent stray fragments from entering the eyes where removal is even more difficult. Clear lenses can deflect a stray fiber end and can prevent it from piercing the eyeball or prevent minute fragmen
17、ts from entering the eye. Safety glasses and protective clothing must be worn when working with fibers. Further information on eye safety precautions can be found in References 2.1 and 2.2 to this document. Eating and drinking in the vicinity of fibers increases the risk of accidental ingestion of g
18、lass fibers. All eating and drinking must not be permitted. In addition, fiber fragments can adhere to skin oils, so after working with fibers, individuals must ensure their hands are thoroughly washed prior to coming into contact with the face or eyes. During installation and repair, all snipped or
19、 cleaved pieces of optical glass fibers must be placed in appropriate dedicated disposal containers. Placing fibers on an adhesive tape strip can be dangerous and must not be encouraged. Fiber waste must never be placed in ordinary garbage for routine disposal. Cables with exposed fiber ends must be
20、 adequately protected or positioned to preclude accidental skin puncture or eye damage. The most effective defense against fiber-related injury is common sense. Unmated connectors and fibers may transmit non-visible radiation and direct viewing with the eye must be avoided at all times. Active fiber
21、 optic systems are not to be inspected with optical magnifying scopes. Protective end caps and connector covers must always be utilized on all unmated connectors. SAE AIR6031 Page 3 of 18 3.2 Optical Power Source Although the optical power level in installations can be relatively low, the minute dim
22、ensions of fiber cores and semiconductor sources makes it possible for intensities to attain surprisingly high values. If an optical cable is disconnected or broken and the exposed end is examined, there is a risk of eye damage. This risk can be exacerbated if a magnifier or other visual aid is used
23、. It should always be assumed that a system is switched on until test equipment can verify the status of optical sources. Moreover, in applications that require higher intensity optical sources, system designers must include additional safety precautions to ensure the safety of maintenance personnel
24、. 3.3 Lasers and Light Emitting Diodes (LED) Lasers commonly used as fiber sources operate at wavelengths of 850, 1300, and 1550 nm, which are all in the infrared part of the light spectrum. Lasers differ from LEDs in the fact that they are coherent, collimated, low divergence and have small spot si
25、zes. The 850 and 1300 wavelengths, along with visible light, are focused by the eye onto the retina. Retinal receptors are particularly sensitive to the 400 to 700 nm wavelength range, but not to wavelengths outside the range; herein lies the danger. The laser will continue to focus on the sensitive
26、 retinal tissue even though the individual is unable to perceive the intense light from the laser. At the focal point, energy density can be high enough to burn the tissue, resulting in blind spots in the individuals visual field or loss of visual activity. This may still occur even though lasers in
27、volved with fiber use are actually of low power compared to other laser types. The class of an individual laser depends on its operating wavelength, its output power, and whether it is pulse or continuous wave. The concentration on low power infrared lasers is sufficient for fiber optic theory. Lase
28、rs/LEDs are classified into four general categories: 3.3.1 Class 1 Considered “eye-safe” to the unaided eye and that no eye damage will result even from prolonged exposure to the direct beam. As the retina more heavily absorbs shorter wavelength light, especially at wavelengths below 550 nm, the max
29、imum output power of Class 1 lasers generally increases with increasing wavelengths. As laser emissions at wavelengths greater than 1400 nm are absorbed by the cornea, no focusing onto the retina occurs and the Class 1 laser maximum output power increases dramatically. 3.3.2 Class 2 Those for which
30、this aversion response will protect an individual from the output. Class 2 lasers include only those emitting visible radiation and many fiber identifiers fall into this category. No Class 2 lasers are used in fiber systems. 3.3.3 Class 3 Possess medium power and produces radiation that can cause ey
31、e damage when viewed directly, or when a magnified reflection is viewed. A diffuse reflection is not usually a hazard. Two subcategories are defined as Class 3A and Class 3B. 3.3.4 Class 4 High power and not used in communication/data cable plant applications. Most lasers used with fiber communicati
32、ons systems are well below the energy levels that would cause skin burns, but the risk of eyesight damage is very real. The danger is highest at optical outputs where energy emerges directly from the laser. 3.4 Eye Safety Wearing safety glasses to protect your eyes from accidental injury is strongly
33、 recommended when handling chemicals, cutting fiber, or, fast moving gas. Pieces of glass fiber are very sharp and can damage the cornea of the eye. SAE AIR6031 Page 4 of 18 3.5 Hazardous Materials All MSDS information should be made available, and appropriate safety and handling procedures used whe
34、n working with chemicals and other hazardous materials. 3.6 Foreign Object Damage (FOD) Fiber optic installation and maintenance will produce large quantities of debris, including packaging, wipes, fibers, and swabs which can lead to FOD. It is essential that all work areas are thoroughly policed an
35、d cleaned throughout the process. 4. CONTAMINATION, CAUSES AND EFFECTS Correct cleaning procedures must be followed to maximize system performance and reliability. 4.1 The Sources of Contamination There are many sources of contamination in the harsh aerospace environment. However, other less harsh e
36、nvironments such as the production floor have many sources of contamination too. Contamination can take various forms, be in combinations, and be delivered with different mechanisms. 4.1.1 The Environment The environment is a natural source of contaminants with a variety of delivery mechanisms. An i
37、nterconnection exposed to the environment for a brief period of time can be contaminated by particulates such as pollen, dust, sand, salt, or chemicals alone or in combination. Examples of endfaces contaminated by the environment are shown in Figures 1 through 8. FIGURE 1 - ENDFACE CONTAMINATED WITH
38、 DRY SALT WATER DEPOSITS SAE AIR6031 Page 5 of 18 FIGURE 2 - ENDFACE CONTAMINATED WITH INSTRUMENT GREASE FIGURE 3 - ENDFACE CONTAMINATED WITH CLEANING COMPOUND SAE AIR6031 Page 6 of 18 FIGURE 4 - ENDFACE CONTAMINATED WITH SYNTHETIC HYDRAULIC OIL FIGURE 5 - ENDFACE CONTAMINATED WITH USED HYDRAULIC OI
39、L SAE AIR6031 Page 7 of 18 FIGURE 6 - ENDFACE CONTAMINATED WITH PETROLEUM GREASE FIGURE 7 - ENDFACE CONTAMINATED WITH COOLANOL HEAT TRANSFER FLUID SAE AIR6031 Page 8 of 18 FIGURE 8 - ENDFACE CONTAMINATED WITH LUBRICATING OIL 4.1.2 Improper Handling Care must be taken when handling a fiber optic inte
40、rconnect. Handling exposes the interconnect to airborne and contact contamination. Accidental touching of connector endfaces is one of the most common sources of contamination. Examples of endfaces contaminated by improper handling are shown in Figures 9 and 10. FIGURE 9 - ENDFACE CONTAMINATED WITH
41、DUST PARTICLES SAE AIR6031 Page 9 of 18 FIGURE 10 - ENDFACE CONTAMINATED WITH SKIN OILS 4.1.3 Improper Cleaning Techniques Poor cleaning techniques are another common source for contaminants. Improper cleaning materials such as tee shirts or pants are also a source of contamination. Figures 11 and 1
42、2 are images of clean connector endfaces that have been contaminated by improper cleaning. FIGURE 11 - ENDFACE CLEANED WITH T-SHIRT SAE AIR6031 Page 10 of 18 FIGURE 12 - ENDFACE WIPED ON JEANS 4.1.4 Contaminant Migration When a connector endface is contaminated and then mated to another connector as
43、 shown in Figures 13 and 14, the contamination transfers to the other connector. This type of contamination migration happens with all contaminants. Contamination migration can take place during connector mating. Test equipment can be a source of contamination as well as the application of excess am
44、ounts of cleaning fluids. FIGURE 13 - ENDFACES BEFORE MATING SAE AIR6031 Page 11 of 18 FIGURE 14 - ENDFACES AFTER MATING 4.2 Results of Contamination Contamination can cause one or more problems including increased insertion loss, increased back reflection, and endface damage. 4.2.1 Increased Insert
45、ion Loss Contamination on the core of a fiber optic connector can physically block the photons from passing from one connector to the next. This will reduce the intensity of the light pulses arriving at the optical receiver. If the reduction in power is above budgeted link losses, system performance
46、 can be impaired. Single-mode fiber is more susceptible to the effects of contamination than multimode fiber because of the smaller core size. Figure 15 shows a single-mode endface before cleaning and Figure 16 shows a single-mode endface after cleaning. SAE AIR6031 Page 12 of 18 FIGURE 15 - SINGLE-
47、MODE ENDFACE BEFORE CLEANING FIGURE 16 - SINGLE-MODE ENDFACE AFTER CLEANING SAE AIR6031 Page 13 of 18 4.2.2 Increased Back Reflection Contamination of the exposed optical fiber or lens may create a refractive index change that causes an increase in back reflection. Back reflections can disrupt laser
48、 operations and impact system performance. 4.2.3 Connector Endface Damage Particulate contamination on the connector endface can permanently damage the connector. The contaminates can create pits or become permanently embedded in the ferrule or fiber. The position of the contaminates at the time of
49、mating will determine the impact on system performance, the core area being most crucial. 5. CLEANING EQUIPMENT AND SUPPLIES The following sections describe commonly used purpose-built equipment and supplies intended for use with fiber optics. 5.1 Compressed Gas Duster The fast moving gas from a compressed gas duster allows the removal of large particles without physical contact. Compressed gas used for this purpose shall have non-contaminati
