1、 AEROSPACE RECOMMENDED PRACTICE Control Measures for Laser Safety in the Navigable Airspace Issued 2004-01 ARP5572 INTRODUCTION On March 26, 1999, the FAA submitted a written request to SAE for assistance in developing standards and regulations concerning outdoor laser operations. In December 1999,
2、the SAE Aerospace Standard 4970 (AS4970) “Human Factors Considerations for Outdoor Laser Operations in the Navigable Airspace” was published by the SAE and forwarded to the FAA. AS4970 provides guidance on assessing the potential hazards of a particular laser beam. In August 2000, the ANSI Z-136.6-2
3、000 “American National Standard for Safe Use of Lasers Outdoors” was published. This Aerospace Recommended Practice (ARP) document provides guidance for control measures to be used optimally during operations of a laser system outdoors in the navigable airspace. It also recommends the control measur
4、e requirements for different outdoor laser systems. Reaffirmed 2010-02SAE 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
5、 any particular use, including any patent infringement arising therefrom, is the sole responsibility of the user.” SAE reviews each technical report at least every five years at which time it may be reaffirmed, revised, or cancelled. SAE invites your written comments and suggestions. Copyright 2010
6、SAE International All rights reserved. No part of this publication 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:
7、877-606-7323 (inside USA and Canada) Tel: 724-776-4970 (outside USA) Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.org SAE values your input. To provide feedbackon this Technical Report, please visit http:/www.sae.org/technical/standards/ARP5572SAE ARP5572 - 2 - FORE
8、WORDThis document applies to control measures designed to mitigate a laser beams potential hazard to aircrews when projected from an outdoor laser system. Related Society of Automotive Engineers (SAE) documents are Aerospace Standard (AS4970) “Human Factors Considerations for Outdoor Laser Operation
9、s in the Navigable Airspace” and Aerospace Recommended Practice (ARP5535) “Observers for Laser Safety in the Navigable Airspace.”Additional control measures may be applicable and are discussed in ANSI Z-136.6-2000, “American National Standard for Safe Use of Lasers Outdoors,” which is the most recen
10、t and authoritative reference regarding outdoor laser operations and control. The purpose of this document is to provide guidance to all laser operators, including industry and government, and to the Federal Aviation Administration (FAA) on the optimal use of control measures during propagation of a
11、 laser beam in the navigable airspace. It also discusses control measures for systems that generate these beams. The SAE G-10T Committee has convened during the past 7 years with representation from at least 17 different entities, public and private, to identify the issues, technologies, and operati
12、onal capabilities of outdoor laser use in navigable airspace. SAE ARP5572 - 3 - TABLE OF CONTENTS 1. SCOPE 4 1.1 Purpose4 1.2 Field of Application.4 2. REFERENCES.4 2.1 Applicable Documents .4 2.1.1 SAE Publications4 2.1.2 ANSI Publications 5 2.1.3 U.S. Government Publications .5 2.2 Other Applicabl
13、e References .5 2.3 Definitions 5 3. LASER CONTROL MEASURES9 3.1 Safety Observers .93.2 Radar .10 3.2.1 Boresight Radar .11 3.2.2 Scanning Radar (Sweeping for laser safety standards, 0.18 to 0.38 m.VISIBLE RADIATION: See LIGHT. WAVELENGTH: The distance between two successive points on a periodic wav
14、e of optical radiation. It is commonly used to provide a numeric description of the color of visible laser radiation. SAE ARP5572 - 9 - 3. LASER CONTROL MEASURES: The following control measures are effective only if the laser system is appropriately installed and operated in accordance with federal,
15、 state, and local regulations, and industry standards. Issues of concern include stability of the laser and platform, physical access to the laser, pointing accuracy of the laser beam, protective housings, and unwanted wavelengths of laser energy. These issues need to be addressed. Detailed safety i
16、nformation is available in ANSI Z136.1-2000 and Z136.6-2000. 3.1 Safety Observers: The safety observer is one of the more proven methods of ensuring that aircraft are not illuminated in-flight by a laser beam. Distance, atmospheric, and environmental parameters may reduce the effectiveness of safety
17、 observers. Additionally, the wavelength (visible versus non-visible) of the laser beam may further reduce the ability of the safety observer to identify the affected airspace. Safety observers may be used in conjunction with other control measures for high-powered laser systems. Safety observers ha
18、ve been demonstrated to be reliable in detecting aircraft at night within short distances (i.e., within about 3 miles) in populated areas. They may be reliable in detecting aircraft farther in semi-populated areas and at much greater distances in remote locations, where city lights are not encounter
19、ed. The Laser Safety Officer (LSO) should not rely solely on safety observers if aircraft can be exposed to hazardous levels of laser energy beyond the observers effective visual range. Safety observers have limited visible range, require training, need frequent breaks, and may be affected by certai
20、n environmental conditions. However, safety observers may have a wider field of view when scanning the airspace, may be readily available, and may be more economical for short-term laser operations. Guidance to FAA personnel reviewing laser demonstration requests and to the laser proponent concernin
21、g the optimal use of safety observers during operation of a laser system is discussed in SAE ARP5535 (Observers for Laser Safety in the Navigable Airspace). That document reviews issues such as vision standards, training, optical aids for the observer, and evaluation of observer effectiveness. SAE A
22、RP5572 - 10 - 3.2 Radar: Radar sends out a radio frequency (RF) signal and displays the signal return reflected from an object. The distance to the object is calculated from the amount of time the signal takes to travel to-and-from the object. Radar is restricted to line-of-sight. Aircraft maneuvers
23、, such as steep turns, rapid climbs or descents, can degrade the radar reflection. Radar is subject to limitations including atmospheric conditions, missed targets, false returns, ground clutter, RF interference, etc. Here is a summary of the general pros and cons of all radar systems: Pros:a. Provi
24、des near real-time to real-time, accurate, long-range information of aircraft positions in the area b. May allow the laser operator to propagate the laser beam at a lower elevation angle c. Especially valuable in the daytime or in inclement weather d. Extended airspace coverage beyond safety observe
25、r capabilities e. Tracking of multiple aircraft simultaneously f. May be used as an automated laser control measure Cons:a. Limited elevation coverage b. Potentially expensive c. May produce hazardous RF emissions d. Susceptible to false or missed radar data e. May require Federal Communications Com
26、mission (FCC) concurrence SAE ARP5572 - 11 - 3.2.1 Boresight Radar: A boresight radar system is typically comprised of control electronics, a transmitter/receiver (transceiver), a radar antenna, and a gimbaled mount. The control electronics performs the following tasks: a. Accepts pointing informati
27、on from the laser system b. Commands the gimbal to point in the direction of the laser beam propagation c. Commands the radar transceiver d. Processes the information gathered by the transceiver e. Indicates that an aircraft is detected f. Abates the laser g. Insures the overall control system is op
28、erational The transceiver develops and transmits the radio frequency (RF) energy and receives the reflected RF signal. The gimbaled mount supports the transceiver and points the transceiver radar antenna. The radar antenna can either be mounted directly to the laser gimbal or can be mounted to a sep
29、arate gimbal. The design of the boresight radar must cover the airspace of concern. Command information is accepted from the laser system by the control electronics. In turn, the control electronics points the transceiver antenna and tracks along the path of the transmitted laser energy. The RF beam
30、 is transmitted by the transceiver antenna and surrounds the laser beam.The envelope of RF energy is several orders of magnitude larger than the envelope of laser energy. Since the radar continually monitors the airspace surrounding the laser beam, reflected RF energy is immediately detected when a
31、plane flies into the path of the radar beam. The control electronics processes this reflected information and develops the aircraft detect signal. This aircraft detect signal is then used to trigger a laser beam abatement system and provides an indicator to the laser operator. See Figure 1. SAE ARP5
32、572 - 12 - FIGURE 1 Boresight Radar System Showing Overlap of RF Energy with Transmitted Laser Energy 3.2.1 (Continued): Boresight radar systems are typically used by scientific, research, or military laser operations that transmit laser energy through the navigable airspace. Satellite laser ranging
33、 systems, LIDAR systems, and guide star optical telescopes have used this system either by itself, or in combination with other aircraft detection systems, such as safety observers or cameras. Boresight radar systems are commercially available. As with any control measure, the capability of a boresi
34、ght system should be evaluated based on the specific proposed operation. Since the radar is pointing along the transmitted laser beam and constantly monitoring the airspace, it is extremely reliable for detecting aircraft. In addition, the time from detection of the aircraft to the development of th
35、e aircraft detect signal is usually in milliseconds. These laser abatement systems may be situated in remote locations or placed near densely populated areas. The boresight radar system is effective even when other control systems are hampered by poor visibility. The boresight radar has a wide range
36、 of coverage (from a few hundred feet to tens of miles). Its very quick response time lends itself well to areas of high-volume air traffic. SAE ARP5572 - 13 - 3.2.1 (Continued): The boresight radar system would not be used when there is a potential that transmitted RF energy may interfere with othe
37、r established operations, such as communication transmissions, deep space monitoring systems, and radio telescopes. Also, the boresight radar system should not be used if ground based objects interfere with the capability of the system. Therefore, not all boresight radar systems are well suited for
38、laser systems that transmit laser energy close to the ground. Local and federal laws and regulations may limit the use of RF energy generating devices, such as radar systems. A boresight radar system can be totally automated. The control electronics of an automated boresight radar system are connect
39、ed to the laser beam abatement system to allow automatic abatement upon aircraft detection. Otherwise, an operator would need to abate the laser manually. Once the aircraft has left the air space monitored by the boresight radar, the system can either be reset automatically or manually to once again
40、 allow transmission of the laser energy through navigable airspace. Here is a summary of the pros and cons of boresight radar systems: Pros:a. Provides real-time information on position of aircraft in the area b. Lowest transmitted RF power of any radar system c. Least expensive radar system d. Wide
41、ly used automated system Cons:a. Laser beams are limited to the restricted field of view of the boresight radar system Bound by the inherent limitations of any radar system Boresight radars vary in efficacy SAE ARP5572 - 14 - 3.2.2 Scanning Radar (Sweeping & Panning): Scanning radars encompass a vas
42、t array of equipment ranging from inexpensive, portable, analog radar, such as one used on a small boat (see Figure 2), to a permanent installation of a multi-million dollar digital radar system (see Figure 3). Permanent radar site installations require costly and timely environmental studies as wel
43、l as ongoing maintenance and operation costs. FIGURE 2 Analog Marine Radar FIGURE 3 FAA Digital Radar Site A scanning radar system rotates or oscillates about an axis. The time to perform a complete rotation varies among different radar systems. Sixty-mile range radar system used by some air traffic
44、 control facilities rotate about every 4 seconds. The rotation time prevents display of a smooth, continuous movement of the aircraft. The direction and speed of the aircraft and the radar rotation time must be taken into account to predict the aircrafts projected position. For example, a jet aircra
45、ft flying at 250 knots could be approximately 0.3 NM from its last known position before the radar completes its rotation and updates the aircraft location. SAE ARP5572 - 15 - 3.2.2 (Continued): The distance and coverage angles of scanning radar systems differ widely. Sweeping radar systems scan 360
46、 about a vertical axis and have a conical volume of airspace directly above the radar antenna that is excluded from radar coverage sometimes called a blind spot. Panning radar systems scan only a portion of the airspace. Used on a limited basis in military applications, a proof of concept has not be
47、en established for the FAA in non-military laser applications. Although possibly enhancing situational awareness, scanning radar may be of limited value to the laser operator. Here is a summary of the pros and cons of scanning radar systems: Pros:a. Up to 360 coverage Cons:a. More expensive than a b
48、oresight radar system b. Higher transmitted RF power than boresight radar system c. Near real-time radar data may be substantially delayed d. Bound by the inherent limitations of all radar systems 3.2.3 Phased Array Radar: Phased array radar systems utilize a specific geometrical arrangement of stat
49、ionary antennas and software to emulate the abilities of sweeping and boresight radars. A phased array radar has no refresh delay or high elevation angle exclusion zones. Additionally, these radar systems are very expensive and have high maintenance costs. The phased array radar permits complete flexibility in its use.Search and tracking functions can be adjusted to optimum use based on local conditions. The radar beam width, azimuth, and elevation can be adjusted to search certain areas more rapidly than others. Even the power transmitted by each element
