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Wide Field of View Primary Optic for Semi-Active Laser Sensor


OBJECTIVE: Develop, investigate, and validate a novel optical primary optic for a wide field of view semi-active laser spot-tracking missile seeker based on a biologically-inspired compound eye for use in the near-infrared spectrum. Provide effective rejection of solar interference, and allow tracking of a target by a missile in flight without the need for a gimbaled sensor. DESCRIPTION: The US Army employs semi-active laser optical sensors on many missile platforms to provide precision guidance to targets. The Army now places a strong emphasis on low-cost missile seekers for use on relatively small missile platforms. The Army requires a novel, non-moving (strap-down) seeker solution in order to reduce cost and complexity as well as enable use on small missile platforms. The Army has a need for a missile seeker system which will not require the use of a moving mechanical structure, such as a gimbal, to maintain track on a target. A strap-down missile seeker must still evaluate the same wide field of regard as that which may be covered by an equivalent gimbaled sensor. A semi-active laser seeker must also operate in an environment which may be rich with background radiance, such as when the sun may be located in the sensor field of view. Small invertebrates have eyes specifically tailored for their tasks [1]. Many of those tasks include wide-field source tracking in high-background environments. The Army therefore recognizes the corollary that a biologically-inspired compound eye-type sensor may provide a novel solution to the problem of a strap-down semi-active laser seeker. PHASE I: Create a design for a novel compound eye seeker and provide performance estimates, analyses, and simulations, to include -but not limited to- resolution, optical throughput, and any measures to predict rejection of solar or other radiation outside of a selected near-infrared band-pass and angles of interest. The novel seeker optics shall be capable of detecting and tracking a target illuminated by a selected laser operating in the near-infrared (900nm-1100nm) wavelength region. The novel seeker optics shall enable narrow band-pass filtering of the source to a 10nm (threshold), 2nm (objective) transmission bandwidth, which shall be effective throughout the entire field of regard of the seeker. The novel seeker design shall allow tracking of the intended laser source throughout the sensor"s field of regard when in the presence of a bright background source (i.e. the sun) located at any field point greater than 2 degrees (threshold), 1 degree (objective) from the intended source. The novel seeker design shall allow implementation on a missile platform as small as 2.75 inches and as large as 7 inches in diameter. The novel seeker shall provide a field of view not less than 25 degrees. The Army will not likely require a field of view greater than 50 degrees. The novel optic shall optimize tracking accuracy and light collection ability while simultaneously providing the previously-stated capabilities. A typical detector sensor for this application is a quadrant detector less than 9.25mm in diameter. The Army shall prefer such a solution for ease of implementation, but will consider other reasonable detector configurations in the interest of cost to performance benefits. Potential risks to achieving a low sensor cost with the proposed concept shall be identified in Phase I. Rough order of magnitude cost estimates on known components are encouraged in Phase I reporting in to reduce risk earlier in the potential Phase II effort. The seeker design shall identify any assumptions or requirements regarding sensor/detector configuration or any additional optics required for the operation of the seeker. Phase I proposals will be technically evaluated on the perceived ability of the technology to meet the previously-stated desired system performance goals as well as achieve future cost goals. PHASE II: Construct and deliver to the Army a prototype sensor system based upon the Phase I design which shall consist of a complete assembly of the novel optical technology, sensor/detector device, electronics for sensor operation, and any hardware or software required to obtain complete signal output from the sensor. The Army technical point of contact shall provide any additional detailed requirements, sensor recommendations, and detector module hardware as necessary, pending a Phase II award. Detailed design analysis and verification thereof shall be performed as part of the Phase II effort. The army shall use results from the analysis effort to run detailed performance models and simulations. The awardee shall provide detailed cost estimation for prototype and production-level quantities of the seeker. PHASE III: Development of the optical technology described herein will have immediate application to laser communications in both military and commercial sectors. The technology should find ready applications in laboratory applications. Additional military spin-offs would include missile warning sensors.
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