Since the Second World War one of the primary threats to aircraft has been infrared"heat seeking"guided missiles. Indeed, more than 80% of aircraft that have been shot-down, have been shot down by infrared guided missiles, whether surface- launched (SAM) or air-launched (AAM). In an effort to neutralize this threat, the launching of heat-emitting decoys ("flares") has been widely used. Flares have three primary disadvantages. First, all but the most primitive heat-seeking missiles are unaffected by flares. Second, the time required after missile-launch detection for flare launch and lighting is relatively long when compared to the total time of a typical aircraft/missile engagement. Third, the number of flares a given platform carries at one time is very limited.

In order to defeat the threat of infrared missiles, directional infrared counter measures (DIRCM) have been developed. In Figure 1, the use of early prior art types of DIRCM, such as the AN/ALQ-204 by Lockheed-Martin (Owego, New York, USA) is depicted. When a threat is anticipated, the operator of the DIRCM in a small aircraft 10 activates a lamp 12, illuminating a broad swathe (roughly 40°) with a beam 14 in a direction from which a threat is expected. The illumination of an infrared seeker 16 of a threat 18 by beam 14 causes seeker 16 to be jammed or destroyed, causing threat 18 to miss small aircraft 10. However, the energy density of beams such as 14 has proven to be insufficient to neutralize the infrared seekers of newer missiles.

A system such as the AN/AAQ-24 (V) NEMESIS by Northrop-Grumman Defensive Systems Division (Rolling Meadows, Illinois, USA) is a significant improvement over earlier DIRCM systems. The operation of such a system is depicted in Figure 2. A MWS (Missile Warning System), such as the AAR-54 (V) by Northrop- Grumman ES3 (Baltimore, Maryland, USA), based on a plurality of detectors 20 mounted on small aircraft 10 detects a missile launch, tracks the launched missile and identifies the missile as a threat 18 to small aircraft 10. The control system of the MWS 22 transfers or"hands-off'the trajectory of threat 18 to DIRCM control system 24.

DIRCM control system 24 then uses dedicated missile tracking system 26 to track threat 18 and directs a light beam 28 (with a width down to about 4°) produced by a gimbaled light source 30 to illuminate threat 18.

An improved DIRCM system similar to that described above and in Figure 2 replaces or supplements gimbaled light source 30 with a laser. Laser DIRCM systems <BR> include the AN/AAQ-24 (V) /Viper by Northrop Grumman Defensive Systems Division (Rolling Meadows, Illinois, USA) or the AN/ALQ-212 (ATIRCM) by BAE Systems (Nashua, New Hampshire, USA). In such a DIRCM system, depicted in Figure 3, a laser 32 is used to illuminate threat 18. Due to the narrowness of laser beam 34 produced by laser 32 (less than 3 microradians) dedicated missile tracking system 26 must be highly accurate, to be able to identify and pinpoint infrared seeker 16 of threat 18 with sufficient accuracy. The intensity and wavelength selectivity of laser beam 34 allows for a highly effective, albeit expensive and not robust, DIRCM system. It is important to note that some laser-based DIRCM systems are hybrid systems: a lamp and a coaxial laser are used to illuminate the threat. Although significantly more expensive, such hybrid configurations are often necessary to overcome the likelihood that in real- time engagements the laser cannot be aimed property for threat neutralization.

An alternative approach is found in the Aero-Gem (Electro-Optical Self- Protection Suite) of Rafael (Israel) which uses a gimbaled wide beam-divergence (between 4° and 10°) non-laser light source 36 to illuminate threat 18, as depicted in Figure 4. Different from the DIRCM systems depicted in Figures 2 and 3, the Aero-Gem lacks a dedicated missile tracking system. Once the MWS control system 22 identifies threat 18, the threat trajectory calculated by the MWS control system 22 is used to direct gimbaled light source 36 to illuminate threat 18 with beam 28. The Aero-Gem system is significantly better than other prior-art systems in that no hand-off time is required. The longer illumination time gained by eliminating the hand-off time as well as the increased chance for seeker illumination gained by width of beam 28 when compared to laser beam 34 (Figure 3) compensates for the lesser intensity of beam 28, allowing for effective threat neutralization. Further, since the time between threat detection and threat engagement is low (less than 100 ms), aircraft survivability is increased. In addition the removal of a dedicated tracking system allows for a significantly less expensive and more robust system.

Depicted in Figure 5 and Figures 6 are two embodiments of an additional DIRCM system developed by Rafael (Israel) and fully described in copending Israeli patent application Nr. 145730.

In Figure 5, small aircraft 10 is-provided with an MWS system including detectors 20 and MWS control system 22. Further, small aircraft 10 is. provided with a DIRCM system including DIRCM control system 24, dedicated missile tracking system 26, and a narrow beam broad-band (that is, non-laser) light source (e. g. Xenon lamp) 38.

When MWS detectors 20 detect a missile launch, MWS control system 22 evaluates if the launched missile is a threat 18. If the missile is a threat, MWS control system 22 hands-off the trajectory of threat 18 to DIRCM control system 24, which aims light source 38 at threat 18 to illuminate threat 18 with narrow light-beam 40. Dedicated missile tracking system 26 tracks threat 18 and ensures that threat 18 remains illuminated by beam 40 by directing light source 38, until threat 18 is no longer a threat to small aircraft 10. Beam 40 produced by light source 38 is relatively narrow, being no more than approximately 4°, and preferably much narrower, e. g. 0. 5° as depicted in Figure 5.

Figures 6A and 6B illustrate a second embodiment of the DIRCM system described in copending Israeli patent application Nr. 145730. In Figures 6, small aircraft 10 is provided with an MWS system including detectors 20 and MWS control system 22. Further, small aircraft 10 is provided with DIRCM system including DIRCM control system 24, dedicated missile tracking system 26, and variable width beam non-laser light source 42. When MWS detectors 20 detect a missile launch, MWS control system 22 evaluates if the launched missile is a threat 18. When threat 18 is detected, DIRCM control system 24 reacts immediately, commanding light source 42 to illuminate threat 18 using the threat trajectory found by MWS control system 22, Figure 6A. The width of beam 44a used to illuminate threat 18 is selected such that threat 18 is effectively illuminated despite the relatively inaccurate trajectory detected by MWS control system 22. Thus, width of beam 44a is relatively broad, e. g. 4° or more. If the accuracy of the threat trajectory found by the MWS is sufficient, the beam width can be reduced.

Simultaneously, with the engagement of threat 18 by beam 44a, MWS control system 22 hands-off the trajectory of threat 18 to DIRCM control system 24 that activates dedicated missile tracking system 26. Once dedicated missile tracking system 26 acquires threat 18, DIRCM control system 24 causes light source 42 to produce narrower light beam 44b, for example, of no more than approximately 1° wide, or even less than 0. 25°, as depicted in Figure 6B. Since dedicated missile tracking system 26 can identify the trajectory of threat 18 much more accurately then MWS control system 22, light beam 44b is much narrower than light beam 44a to increase the energy density illuminating threat 18, and consequently the neutralization efficiency.

The DIRCM systems known in the art, especially those produced by Rafael, are highly effective in defending certain types of aircraft. Aircraft with a small thermal signature or fast and agile aircraft equipped with prior art DIRCM systems have a relatively high survivability when challenged by an infrared-guided threat.

In recent years the need to defend other aircraft, especially large civilian or military passenger transports, has increased. Relatively cheap shoulder-fired missiles are becoming increasingly available to militants who may target a passenger aircraft to further political ends. Unfortunately, prior art non-laser DIRCM systems are incapable to defend large passenger transport aircraft from such missiles. Passenger aircraft are slow and virtually non-maneuverable, especially during the take-off and landing stages of flight. In addition, as these are multi-engine aircraft designed for efficient peacetime flight, the thermal signature of these aircraft is very large. The illumination power deployed and engagement time available for prior art non-laser DIRCM systems to neutralize a thermal-guided threat is insufficient to effectively protect this type of aircraft. Suitable and sufficiently powerful lamps are unavailable. The illumination power available to laser DIRCM systems may suffice. However laser DIRCM systems are generally expensive and not robust as the dedicated missile tracking system must be exceptionally accurate and mechanical components of the gimbal-mount need to have an exceptional high tolerance and tracking accuracy.

There is a need for a non-laser DIRCM system able to deploy significantly greater illumination power then known in the art in order to neutralize a infrared-guided threat to an aircraft with a large thermal signature. Such a system must be relatively cheap to allow acceptance in the civilian aircraft market. In addition, such a DIRCM system must be easily attached to existing aircraft with little modification when the aircraft must fly in high-risk airspace. The system must also be easily detachable when the aircraft is to fly in low-risk airspace in order to lower fuel costs and increase cargo capacity. Such a system is preferably simple to operate with little training required.

SUMMARY OF THE INVENTION According to the teachings of the present invention, there is provided a DIRCM system, useful for defeating a threat posed by a thermal-guided threat made up of : (a) a missile warning system (MWS); (b) a DIRCM control system; (c) two or more individual non-laser light sources (e. g. arc lamps such as Xenon lamps) and (d) a trigger, configured to synchronize activation and deactivation of the individual light sources to within 1 millisecond, preferably to within 1 microsecond.

Also according to the teachings of the present invention there is provided a system for neutralizing the threat posed by a guided missile to a platform comprising (a) at least two non-laser light sources (e. g. arc lamps such as Xenon lamps), (b) a trigger (e. g. a pulser) configured to synchronize activation of the at least two light sources to within less than 1 millisecond (preferably to within less than 1 microsecond, even more preferably to within less than 1 nanosecond), and (c) a control system, configured to aim beams produced by the at least two light sources at a missile based on the trajectory the said missile. As in prior art DIRCM systems, illumination of the missile by the beams is effective in neutralizing the threat posed by the missile.

According to a feature of the present invention, a respective beam produced by each one of the light sources has an angular width greater than 0. 01°.

According to a feature of the present invention, the at least two light sources are gimbal-mounted. According to a further feature of the present invention, at least two of the at least two light sources are mounted in a single gimbal mount. According to a still further feature of the present invention, the least two of the at least two light sources are mounted coaxially in the single gimbal mount.

According to a feature of the present invention, the system further comprises (d) a mechanism for varying the beam widths of the at least two light source and the control system is configured to control the mechanism for varying the beam widths.

According to a feature of the present invention, the system further comprises (d) a missile warning system (MWS) configured to supply the control system with a first trajectory of the missile.

According to a feature of the present invention, the system further comprises (e) a dedicated missile tracking system (preferably separate from the MWS) configured to supply the control system with a second trajectory of the missile. Preferably, at least some of the components (e. g. threat sensors) of such a dedicated missile tracking system are gimbal mounted, preferably on the same gimbal mount on which one or more of the light sources are mounted.

According to a feature of the present invention, the system can be an integral part of a platform that carries the system such as an airplane or an airfield control tower.

According to a feature of the present invention, at least some of the components of the system are deployed in one or more separate packages (e. g. pods or nacelles) configured to be easily and reversibly attachable to and detachable from the platform (e. g. aircraft). on which the packages are mounted, for example to hard points on the wings or aircraft underbelly. When deployed in separate packages and not an integral part of the platform, the DIRCM system receives necessary power from the platform itself, or, according to a preferred feature of the present invention, the separate packages are equipped with an autonomous power supply (for example, batteries, fuel cells, generators).

According to a feature of the present invention, the system further comprises (d) a remote control configured to allow an operator to activate the system.

According to a feature of the present invention, at least two components of the system are equipped with wireless communication means, configured to allow wireless transfer of information between the least two components of the system. For example, a remote control is equipped for wireless communication with the control system.

According to a further feature of the present invention, the DIRCM system is configured to operate automatically with substantially little pilot intervention. For example, the pilot can simply activate/inactivate the DIRCM system and initiate a self- test. If the DIRCM system fails a self-test, the pilot is then warned and is then able to contact technical personnel. According to a still further feature, the DIRCM system of the present invention is configured to be automatically activated when the aircraft is at risk (based on, for example, altitude, velocity, location or initiation of take-off/landing procedures). Once activated, the system preferably automatically engages and neutralizes the threat posed by missiles.

There is also provided according to the teachings of the present invention a method for neutralizing the threat posed by a guided missile comprising (a) detecting a guided missile, (b) detecting a trajectory of said guided missile, and (c) simultaneously illuminating the guided missile with beams from at least two non-laser light sources wherein activation of the at least two non-laser light sources is synchronized (preferably to within less than 1 millisecond of each other, more preferably to within less than 1 microsecond of each other, and even more preferably to within less than 1 nanosecond of each other) and wherein illumination of the missile with the beams is effective in neutralizing the threat posed by the missile.

According to a feature of the method of the present invention, the activation of the at least two light sources is triggered by a pulser.

According to a feature of the method of the present invention a respective beam produced by each one of the at least two light sources has an angular width greater than 0. 01°.

According to a feature of the method of the present invention at least two of the at least two light sources are mounted coaxial.

BRIEF DESCRIPTION OF THE DRAWINGS The invention is herein described, by way of example only, with reference to the accompanying drawings, where: FIG. 1 (prior art) is a schematic depiction of a permanently lit wide-beam DIRCM system; FIG. 2 (prior art) is a schematic depiction of a DIRCM system using a gimbal- mounted lamp and a dedicated missile tracking system; FIG. 3 (prior art) is a schematic depiction of a DIRCM system using a gimbal- mounted laser and a dedicated missile tracking system; FIG. 4 (prior art) is a schematic depiction of a DIRCM system using a gimbal- mounted lamp and the MWS to direct the light beam; FIG. 5 (prior art) is a schematic depiction of a DIRCM system using a gimbal- mounted narrow beam lamp and a dedicated missile tracking system; FIGS. 6A and 6B (prior art) is a schematic depiction of a DIRCM system using a gimbal-mounted variable width beam and a dedicated missile tracking system; FIGS. 7A and 7B are schematic depictions of light sources useful in a DIRCM system of the present invention; FIG. 8 is a schematic depiction of an embodiment of the DIRCM system of the present invention using six individual gimbal-mounted lamps mounted in an underbelly nacelle ; FIG. 9 is a schematic depiction of an embodiment of the DIRCM system of the present invention using four individual gimbal-mounted lamps and a dedicated missile tracking system mounted in an underbelly nacelle; FIGS. 10A and 10B are a schematic depiction of an embodiment of the DIRCM. system of the present invention using four individual variable beam-width gimbal- mounted lamps and a dedicated missile tracking system mounted in an underbelly nacelle; and FIG. 11 is a schematic depiction of an embodiment of the DIRCM system of the present invention where the components of the DIRCM system are mounted in an aircraft-attachable pod and control of the DIRCM system is performed using wireless communications.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is of a DIRCM system that is effective in neutralizing an infrared-guided threat to a non-agile and high thermal signature aircraft, such as a commercial passenger aircraft yet is cheap and easy to operate. The DIRCM system of the present invention simultaneously illuminates a threat with two or more individual non-laser light sources so that the illumination power density is sufficient to neutralize the threat.

The principles and operation of a DIRCM system according to the present invention may be better understood with reference to the drawings and the accompanying description.

The basic principle of the present invention is to provide a method and a device to illuminate the seeker of a threat with sufficient energy to neutralize the threat without using a laser and overcoming the fact that no single appropriate non-laser light-source currently available is sufficiently intense. The approach to solving this problem is by providing two or more non-laser light sources to simultaneously illuminate the threat.

Two major problems must be overcome. The first is that all of the light sources must be synchronized to turn on and to turn off within less than a millisecond of each other, preferably within less than a microsecond of each other, and more preferably within less than a nanosecond of each other. The second is that all of the light sources must all be directed at the seeker of the threat.

Once these two problems are solved, a sufficient number of individual light sources are provided to neutralize a threat. The exact number of individual light sources necessary is dependent on the size of the thermal signature of the protected target, the engagement range countenanced and the nature of the threat. The number of light sources necessary is easily calculated by one skilled in the art. A type of device able to overcome the two problems is schematically depicted in Figures 7.

In Figure 7A, a preferred embodiment of a lamp assembly 46 of the present invention is depicted. Inside a turret 48 is contained a gimbal mount 50. Rigidly and coaxial mounted in gimbal mount 50 are six individual light sources 52a, 52b, 52c, 52d, 52e and 52f. Each one of light sources 52 has a lens diameter of roughly 5 cm.

Supplying power to light sources 52 is a pulser 54.

When necessary, pulser 54 triggers light sources 52a, 52b, 52c, 52d, 52e and 52f to produce respective light beams 56a, 56b, 56c, 56d, 56e and 56f. Despite the fact that light sources 52 are coaxial, due to the finite angular width of beams 56, at some distance beams 56 effectively overlap to produce a single composite beam of light. The distance from which light beams produced by light sources such as 52 arrayed in a coaxial hexagonal arrangement as in lamp assembly 46 produce a composite light beam of at least 5 cm width as a function of the angular width of beams 56 is listed in Table 1.

TABLE 1. Distance for production of 5 cm composite beam for lamp assembly 46 angular width (degrees) distance (meters) 0.0191 300 0.25 22.9 2.0 2.9 4.0 1.4 In Figure 7B, a lamp assembly 58, related to lamp assembly 46 of Figure 7A is depicted. Lamp assembly 58 is equipped with four light sources, 52a, 52b, 52c and 52d, and with an optical device 60, separated from lamps 52 by a non-transparent partition 62. Partition 62 prevents blinding of optical device 60 by light sources 52. Optical device 60 is a sensor of dedicated missile tracking system 26, dedicated to the actual tracking of a threat. Supplying power to light sources 52 is a pulser 54.

When necessary, pulser 54 triggers light sources 52a, 52b, 52c and 52d to produce light beams 56a, 56b, 56c and 56d, respectively. Despite the fact that light sources 52 are coaxial, due to the finite angular width of beams 56, at some distance beams 56 effectively overlap to produce a single composite beam of light. The distance from which light beams produced by light sources such as 52 arrayed in a coaxial square arrangement as in lamp assembly 58 produce a composite light beam of at least 5 cm width as a function of the angular width of beams 56 is listed in Table 2.

TABLE 2. Distance for production of 5 cm composite beam for lamp assembly 58 angular width (degrees) distance (meters) 0.0135 300 0. 25 16.2 0.5 8.1 1 4. 0 2 2.0 4 1.0 For two or more individual light sources to effectively illuminate a single threat within the context of a DIRCM system, the illumination of all the light sources must be synchronized to better than millisecond accuracy, preferably to better than microsecond <BR> <BR> accuracy and even more preferably to nanosecond accuracy. "Pulsers" (high voltage pulsed power supplies) are devices known to one skilled in the art that can be used to synchronize light source activation and deactivation in a fashion suitable for use in the present invention. For example, pulsers based on cascaded field effect transistors (FET) which can be synchronized to the order of nanoseconds are commercially available, for <BR> <BR> example, from Kentech Instruments Ltd. , (Oxfordshire, United Kingdom). Such pulsers can be used to synchronize the plurality of light sources of the DIRCM system of the present invention.

Depending on the details of the DIRCM system the angular beam widths of light sources 52 as well as the method of use of the DIRCM system itself are determined.

Figure 8 is a schematic depiction of an aircraft 64 equipped with a first embodiment of the DIRCM system of the present invention, confined within a nacelle 66 attached to the underbelly of aircraft 64. When MWS detectors 20 and MWS control system 22 identify threat 18, the threat trajectory calculated by the MWS control system 22 is used by DIRCM control system 24 to direct a lamp assembly 46, similar to that depicted in Figure 7A, to illuminate threat 18 with composite beam 70. Composite beam 70 is composed of six separate relatively wide (e. g., 4°) beams such as beams 56 in Figure 7A. As a result, the angular width of composite beam 70 is 4° and already at a distance of 1.4 meters (see Table 1) is large enough to be effectively illuminate threat 18, in analogy to the DIRCM system depicted in Figure 4. The advantages of a DIRCM system as depicted in Figure 8 is the speed of reaction as no hand-off time is required and the fact that the lack of a dedicated tracking system allows for a much less expensive and more robust system. The fact that threat 18 is simultaneously illuminated by more than one lamp (in lamp assembly 46 there are six lamps 52) means that enough illumination power density is available to neutralize threat 18.

Figure 9 is a schematic depiction of an aircraft 64 equipped with a second embodiment of the DIRCM system of the present invention, confined within a nacelle 66 attached to the underbelly of aircraft 64. The second embodiment of the DIRCM system of the present invention includes a dedicated missile tracking system 26, which allows for accurate aiming of a gimbaled lamp assembly 58 to illuminate threat 18 with a narrow composite light beam 72 (e. g. , 0. 5° in Figure 9). Gimbaled lamp assembly 58 in Figure 9 is similar to gimbaled lamp assembly 58 depicted in Figure 7B.

When MWS detectors 20 detect a missile launch, MWS control system 22 evaluates if the launched missile is a threat 18. If the missile is a threat, MWS control system 22 hands-off the trajectory of threat 18 to DIRCM control system 24. DIRCM control system 24 activates dedicated missile tracking system 26 (of which optical device 60 is a component) to detect the trajectory of threat 18 with relatively high accuracy. Using the accurate trajectory of threat 18, DIRCM control system 24 directs narrow composite light beam 72 to illuminate threat 18. Dedicated missile tracking system 26 continuously tracks threat 18, ensuring that threat 18 remains illuminated by composite beam 72 until threat 18 is no longer a threat to aircraft 64.

Composite beam 72 is composed of four separate relatively narrow beams such as beams 56 in Figure 7B, being no more than approximately 4°, preferably less than 2°, more preferably less than 1°, even more preferably less than 0. 5°, and most preferably less than 0. 25°. As a result, the angular width of composite beam 72 is less than 4°, less than 2°, less than 1°, less than 0. 5° and less than 0. 25°, respectively. From Table 2 is seen that composite beam 72 is large enough to be effectively illuminate threat 18, already at distances of 1, 2,4, 8 and 16 meters respectively, in analogy to the DIRCM system depicted in Figure 5.

Dedicated missile tracking system 26 of Figure 9 (and Figure 5) must detect a trajectory of threat 18 in order to aim composite beam 72 with a few tenths of a degree width as opposed to a 3 microradian (-0. 005°) wide laser beam 34 of the DIRCM system depicted in Figure 3. The DIRCM system depicted in Figure 9 is simple and robust relative to dedicated tracking system 26 depicted Figure 3. The fact that threat 18 is simultaneously illuminated by more than one lamp (in Figure 9, four lamps 52) means that enough illumination power density is available to neutralize threat 18.

Figures 1 OA and 1 OB illustrate a third embodiment of the DIRCM system of the present invention confined within a nacelle 66 on the underbelly of aircraft 64. The second embodiment of the DIRCM system of the present invention includes a dedicated missile tracking system 26, which allows for accurate aiming of a composite beam 76 produced by gimbaled lamp assembly 74. Gimbaled lamp assembly 74 in Figures 10 is similar to gimbaled lamp assembly 58 depicted in Figure 7B except that gimbaled lamp assembly 74 is provided with four variable beam-width light sources.

In Figures 10, when MWS detectors 20 detect a missile launch, MWS control system 22 evaluates if the launched missile is a threat 18. When threat 18 is detected, DIRCM control system 24 reacts immediately (less than 100 ms), directing the variable beam-width light sources of gimbaled lamp assembly 74 to illuminate threat 18 using the threat trajectory found by MWS control system 22, Figure 10A. The width of composite beam 76a used to illuminate threat 18 is selected such that threat 18 is effectively illuminated despite the relatively inaccurate trajectory detected by MWS control system 22. Thus, width of beam 76a is relatively broad, e. g. 4° : If the accuracy of the threat trajectory found by MWS control system 22 is sufficient, the beam width is preferably 2° or greater and more preferably 1 ° or greater. As in first embodiment of the present invention depicted in Figure 8 there is no hand-off delay and threat 18 is immediately engaged.

Simultaneously with the engagement of threat 18 by composite beam 76a, DIRCM control system 24 activates dedicated missile tracking system 26 of which optical device 60 is a component. Once dedicated missile tracking system 26 acquires an accurate trajectory of threat 18, DIRCM control system 24 aims gimbaled lamp assembly 74 based on the accurate trajectory found by dedicated missile tracking system 26. DIRCM control system 26 causes the variable beam-width light sources of gimbaled lamp assembly 74 to produce narrow composite light beam 76b for example, with a width of no more than approximately 1° wide, preferably no more than 0. 5° wide and even more preferably less then 0. 25°, as depicted in Figure IOB. Since dedicated missile tracking system 26 can identify the trajectory of threat 18 much more accurately then MWS control system 22, composite light beam 76b is much narrower in order to increase the energy density illuminating threat 18 and, consequently, threat neutralization efficiency.

The relative width of composite light beam 76a and 76b is ultimately determined by the accuracy of the trajectories determined by the MWS control system 22 and dedicated missile tracking system 26, respectively. For example, if MWS control system 22 is configured to determine a trajectory as accurately as in the DIRCM system of Figure 4, then the width of composite light beam 76a is approximately 4°. If the trajectory determined by dedicated missile tracking system 26 is sixteen times more accurate, then the width of composite light beam 76b is approximately 1°.

Production of a light source, such as a Xenon lamp, with a variable beam width in the order of from about 4° to down about 0. 5° is known to one skilled in the art by use, for example, of variable geometry reflectors or variable focal length lenses. Means necessary for making variable beam width lamps are commercially available, for example from Ballantyne of Omaha, Inc. , (Omaha, Nebraska, U. S. A.).

The embodiments of the present invention described hereinabove and depicted in Figures 7,8, 9, l0A and 10B have four or six individual light sources. In general, however, the number of light sources provided is determined on a case by case basis to ensure neutralization of anticipated threats. Operation and design of a system of the present invention with a greater or lesser number of individual light sources is, in analogy to the embodiments described hereinabove, clear to one skilled in the art.

The purpose of the DIRCM system of the present invention is to defend large passenger aircraft from thermal-guided threats. Clearly the lion's share of such aircraft do not need to be defended from thermal-guided threats, making it undesirable that the DIRCM system of the present invention be fully integrated into the aircraft during production. Thus it is exceptionally preferable that the DIRCM system of the present invention be easily attachable and detachable to an aircraft. Further, since the DIRCM system is not a permanent fixture of an aircraft, the DIRCM system of the present invention is preferably operable without necessitating extensive pilot training.

The convenient attachment of peripheral, auxiliary or extra equipment to an aircraft by the use of nacelles or pods attached to the wings or hulls of aircraft is well known in the art. Such nacelles or pods are used to equip an airplane with, amongst others, fuel, armaments, flares and electronic warfare equipment. Most modern aircraft are constructed with strong points at appropriate places for the attachment of nacelles or pods. For example, most large transport aircraft are equipped with at least one strong point on each wing for the purpose of attaching an extra motor. These points are suitable for the attachment of pods or nacelles The specific details of any nacelle or pod deploying the DIRCM system or components of the system of the present invention are determined by the parameters of the aircraft to be protected. For explanatory purposes, a non-limiting embodiment of a DIRCM system of the present invention is schematically depicted in Figure 11.

A DIRCM system of the present invention, provided in an attachable pod 78, is depicted in Figure 11. Pod 78 contains MWS detectors 20, MWS control system 22, DIRCM control system 24, elements of dedicated missile tracking system 26 and pulser 54. Pod 78 is also equipped with a lamp assembly 58, analogous to lamp assembly 58 depicted in Figure 7B. Lamp assembly 58 is equipped with four light sources 52 optically separated from optical device 60 by partition 62. Partition 62 prevents blinding of optical device 60 by light sources 52. Optical device 60 is functionally associated with dedicated missile tracking system 26. Pulser 54 is configured to trigger synchronized operation of light sources 52.

As is clear to one skilled in the art, pod 78 requires electrical power to operate.

Pod 78 can optionally be equipped with an electrical connector. to draw electrical power from the aircraft to which pod 78 is attached. However, there are many factors that make it preferable that a DIRCM system of the present invention provided in a detachable pod such as pod 78 have an autonomous power supply.

There are many methods to supply the power necessary for operation of the DIRCM system of the present invention, including for example fuel cells, power packs, capacitors, batteries and generators. Since it is expected that most often the DIRCM system of the present invention is operational for only short times during a single flight (e. g. during take-off and landing) the capacity and physical size of an autonomous power supply can be modest. In Figure 11, pod 78 is equipped with an auxiliary power unit 80. Auxiliary power units are compact and efficient turbine generators that are well known in the field of aviation and commercially available in many sizes, for example <BR> <BR> from Hamilton Sundstrand (Windsor Locks, Connecticut, U. S. A. ). Fuel 82 for operation of auxiliary power unit 80 is available in pod 78.

The DIRCM system depicted in Figure 11 is configured for ease of use.

Therefore, the only user-control present is a remote control unit 84 configured for wireless communication with DIRCM control system 24 in pod 78 through a transceiver 86. Remote control unit 84 is configured to allow two-way communications with DIRCM control system 24 and includes only three buttons. The three buttons are: button 88"ON"to activate the DIRCM system when the pilot believes a threat exists; button 90"OFF"to deactivate the DIRCM system when necessary; and button 92"TEST"to initiate a self-test so that the pilot can be assured that the DIRCM system is properly functioning. A light 94 is illuminated by signals transmitted by transceiver 86 of pod 78 when the DIRCM system is activated.

The DIRCM system depicted in Figure 11 is simple to use. Pod 78 is attached to an aircraft that is to fly to a dangerous airfield. Depending on aircraft parameters and the number of strong points, a plurality of pods 78 can also be attached. The pilot is supplied with a remote control unit 84 for each pod attached (although one remote control unit 84 may be configured to communicate with a plurality of pods 78). A few minutes before landing, and when well outside the rarige of an expected threat, the pilot uses remote control unit 84 to activate the DIRCM system. Auxiliary power units 80 are turned on and MWS detectors 20 seek a threat. If a threat is detected, the threat is engaged substantially as described hereinabove.

An even more automatic system than that depicted in Figure 11 is countenanced.

A DIRCM system can be configured to automatically activate itself with no operator intervention. The DIRCM system when installed monitors data from systems such as an altimeter, a flight speed indicator, flight control systems or a GPS location device to self-activate in high risk situations. Only upon a failure of a self-test is the pilot warned.

The pilot then contacts technical personnel.

While the invention has been described with respect to a limited number of embodiments, it will be appreciated that many variations, modifications and other applications of the invention may be made. For example, although described as being useful against infrared guided missiles, with appropriate modification, the DIRCM system of the present invention can be used against threats guided by radiation at other frequencies (e. g. UV/VIS).

The system of the present invention can be used to neutralize munitions that are a threat to an entity that is not the platform on which the system of the present invention is deployed. For example, a DIRCM system of the present invention may be located at a ground station for example at the periphery of a threatened airfield. A special DIRCM aircraft (manned and unmanned aircraft, blimp, zeppelin) equipped with the DIRCM system of the present invention may be deployed in the vicinity of a high risk airfield.

This is useful to allow large supply aircraft to land at the airfield even before the airfield is completely secured, for example in the framework of a rapid deployment force. Thus, it is understood that the specification and examples are illustrative and do not limit the present invention.