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ELECTRONICS AND ELECTROMAGNETICS Laser Decoy System for Small termeasure (LaCM) to detect, identify, and counter Ground Platforms laser-guided threats to the small surface platforms. R. Evans and S. Moroz LaCM Description: Laser-guided weapons are Tactical Electronic Warfare Division precisely directed by an operator who illuminates the intended impact point with a laser beam. Guidance Introduction: Increasingly, U.S. Navy ships are logic in the weapon detects this pointing laser reflection operating in the littorals, where they may be exposed from the intended target and corrects the weapon’s to a variety of threat weapons including laser-directed trajectory to impact the illumination point. A first step threats. These laser-guided threats are also of very high to countering these threats is to detect that the pointing concern to the Marines as they operate lightly armored laser designator energy is illuminating the defended vehicles in hostile areas. A laser decoy concept was platform. For this demonstration, the Goodrich Com- developed demonstrating a capability to counter these pany’s laser detection sensor was combined with signal types of threats. With relatively small-sized vehicles, the processing logic to alert the EWISSP system to an laser decoy needs to be compact and affordable. Short attack. threat alert times dictate a very rapid response from Major LaCM components included a counter- the laser decoy. These constraints were met in the laser measure laser to confuse the threat weapon, an optic decoy that was developed and demonstrated as part of combination to direct the LaCM laser energy toward the EWISSP (Electronic Warfare Integrated System for the threat, and an erectable 2-meter mast to provide Small Platforms) project. an improved defensive geometry. On alert of an attack, One of the Office of Naval Research (ONR) the LaCM mast is deployed from a stowed position Future Naval Capability (FNC) programs, EWISSP that maintains the platform’s relatively low profile. was developed as a low-cost integrated system to Next, the LaCM beam is configured by optics at the improve the survivability of small surface platforms top of the mast to direct the countermeasure energy. against precision guided threats. The EWISSP design This is followed by transmission of the energy from included sensors to detect the threat, processing to the LaCM laser to jam the threat sensor, preventing classify the threat type, and countermeasure responses the threat weapon from hitting the targeted platform. to negate the effectiveness of the threat. The small Figure 8 illustrates the LaCM countermeasure concept platforms with small crew size can be protected with that presents both omnidirectional and spot ground the automated operation of EWISSP. Although the jamming beams that can counter the full range of laser- Marines’ Expeditionary Fighting Vehicle (EFV) was guided threats. the initial transition target for the EWISSP technology, the system was designed to work with the full array of LaCM Testing: As part of the testing, the LaCM small surface platforms including the Light Armored defended platform was attacked by threat seekers Vehicle (LAV), the Landing Craft Air Cushion (LCAC), carried on a helicopter. The helicopter flew a full range and the Landing Craft Utility (LCU) ships. EWISSP of trajectories representative of those typically fol- was jointly developed by a team including ONR, NRL, lowed by threats. Figure 9 shows the LaCM hardware and Northrop Grumman. The NRL focus was in the with the mast erected on a surrogate HMMWV (High development and demonstration of the Laser Coun- Mobility Multipurpose Wheeled Vehicle) test platform Omni - Jam Beam High Angle Threat Low Angle Threat Ground Projection FIGURE 8 Laser Countermeasure (LaCM) concept. 162 2009 NRL REVIEW ELECTRONICS AND ELECTROMAGNETICS LaCM Optics Captive Threat Seekers LaCM Mast FIGURE 9 LaCM testing with captive seekers on helicopter. LaCM Omni-jammer FIGURE 10 Reference infrared image of LaCM testing. Threat Designator LaCM Ground Spot Spot along with instrumented threat seekers installed on effective in countering the threat seekers over a full set a test helicopter. This testing covered a wide range of of engagement geometries. backgrounds and attack geometries. A representative scene presented to the threat seekers is presented in Summary: The helicopter testing followed an the infrared image of Fig. 10. The center of the LaCM extensive test series that was conducted at multiple test omni-jammer is seen as the small dot. The ground spot sites with many climatic and background conditions. from the laser decoy lures the threat away from the In all of the tests, the concept was demonstrated to HMMWV that is being illuminated by the threat’s laser effectively counter the precision laser-guided threats. designator. During the testing, the LaCM was highly [Sponsored by ONR] 2009 NRL REVIEW 163