An optical system utilized to provide guidance information in the form of a modulated beam for a beamrider missile during its rocket powered flight phase. Our system comprises first and second zoom type optical subsystems arranged to function cooperatively in object space, utilizing coincident lines of sight, with these optical subsystems serving to provide guidance information to the missile when the exhaust plume from its rocket engine is relatively difficult to penetrate. The first optical subsystem is utilized in a closed loop servo system for positioning a mirror gimballed about two axes, such that it continuously tracks the missile. The second optical subsystem, along the optical axis of which the modulated beam is directed, comprises a negative optical group and a positive optical group combined into a defocusable beam expander. These groups are initially defocussed, and during flight of the missile, the negative group is movable in a linear manner away from the positive group, toward the focussed position, so as to maintain by utilization of the gimballed mirror, a constant beam diameter at the missile. This beam contains guidance information for directing the missile to a selected target, and quite advantageously, these positive and negative groups are constructed to be individually free of spherical aberration and coma, such that the shape of the transmitted beam is not disturbed in any of the zoom positions.
A method for reducing error (when compared to conventional methods) in estimates of radiance inferred from measurements of irradiance provided by detectors in an array of a sensor. By using measurement data from each cluster in a set of nested clusters in the neighborhood of a selected detector and applying selected mathematical relationships, an accurate estimate is obtained. A source of this error springs from the non-uniformity of illumination that occurs within the finite solid angle field of view (FOV) of a detector in a sensor array due, at least in part, to intrinsic unpredictable characteristics of the scene being viewed by the sensor array. To achieve fine resolution with reasonably sized detector FOVs, this non-uniformity makes impractical the use of average values of illumination within the solid angle defining the detector's FOV, the conventional method for deriving estimates of radiance.
Methods and apparatus for guidance systems according to various aspects of the present invention operate in conjunction with a projectile including a guidance system having a guidance controller, a detector, and an optical system. The guidance controller controls the path of the projectile according to signals from the detector. The detector generates signals according to an angle of incident energy. The optical system transfers the energy to the detector via a spreader and a condenser. The spreader spreads the incident energy, and the condenser converges the spread energy onto the detector.
The Nutated Beamrider Guidance Using Laser Designators provides a means of roducing an accurate laser beamrider command guidance link between the launch platform and the missile during its flight through the addition of a simple variable offset nutator mechanism to existing Army laser designators. Such a beamrider guidance enables the missile to determine its position in the guidance field by measuring the angle of arrival of side scatter from the pulsed beam. These measurements result in the production of correctional signals which cause the missile to move closer to the boresight axis for eventual impact on the target.
A laser beam steering module includes an optics assembly that directs a first portion of a laser beam through an output aperture and a second portion of through a sensing path. The optics assembly adjusts a position of the laser beam through the output aperture and sensing path responsive to position control signals. A sensor array in the sensing path receives the second portion of the laser beam and in response thereto generates electrical beam position signals indicating a position of laser beam through the output aperture. The electrical beam position signals have values that are a function of a temperature of the sensor array and are used in generating the position control signals to adjust the position of the laser beam as a function of the values of the electrical beam position signals. A thermal stabilization circuit stabilizes the temperature of the sensor array responsive to thermal control signals.
