Holographic system for interactive target acquisition and tracking
First Claim
1. A laser target acquisition and tracking system with compensation for aberrations comprising:
- laser means for directing a first wide divergence beam of radiation through media toward at least one target wherein said target reflects a portion of said radiation as a return beam,means for interfering said return beam with a reference beam on an electronic detector for generating an interference pattern in the form of electronic signals containing information about said target and said media,hologram processor means responsive to said electronic signals from said electronic radiation detector for processing said signals to form an electronic hologram pattern;
a spatial light modulator responsive to said electronic hologram pattern from said hologram processor means for recording said processed hologram,and means for directing a beam of radiation onto said hologram recorded on said spatial light modulator for providing a conjugate beam representative of said return beam, said conjugate beam being directed to said target.
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Accused Products
Abstract
A holographic laser target acquisition and tracking system with aberration compensation including a detector array, a master-oscillator (MO), a hologram processor, a spatial light modulator (SLM) and a slave oscillator which is referred to as a Holographic Interactive Tracker system. The operation of the system consists of two steps. In step one, an acquisition step, a diverging laser beam (acquisition beam) from the laser oscillator is transmitted to a target 38. The beam divergence is typically much larger than the target angular extent. A fraction of the diverging energy intercepted by the target is returned, as a beam or as diffuse radiation, and collected by a receiver optic. This target return is interfered with a master oscillator beam from the MO on the electronic detector array, thereby forming an electro-optic hologram. The detector array is read out pixel by pixel and applied to the hologram processor which enhances the hologram by subtracting out the d.c. component. The hologram is processed, and the resulting pattern is transferred pixel by pixel to the spatial light modulator (SLM) where the electronic hologram is written in as a phase hologram. In step two, an engagement step, a beam from the same or a separate laser oscillator is reflected off the SLM. The SLM output consists of multiple beams (orders) of radiation, one of which is the conjugate of the target return radiation. Through the properties of phase conjugation, this beam retraces the target return path while, at the same time, the wavefront distortions are undone, resulting in maximum energy delivery to the target. By repeating acquisition and engagement steps one and two as the target moves, the system automatically tracks it.
42 Citations
21 Claims
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1. A laser target acquisition and tracking system with compensation for aberrations comprising:
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laser means for directing a first wide divergence beam of radiation through media toward at least one target wherein said target reflects a portion of said radiation as a return beam, means for interfering said return beam with a reference beam on an electronic detector for generating an interference pattern in the form of electronic signals containing information about said target and said media, hologram processor means responsive to said electronic signals from said electronic radiation detector for processing said signals to form an electronic hologram pattern; a spatial light modulator responsive to said electronic hologram pattern from said hologram processor means for recording said processed hologram, and means for directing a beam of radiation onto said hologram recorded on said spatial light modulator for providing a conjugate beam representative of said return beam, said conjugate beam being directed to said target. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 21)
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11. A method for pointing a laser beam at a target with a compensation for aberrations caused by the intervening media, comprising:
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illuminating target space with laser radiation, receiving at a receiver at least one radiation return reflection from a target in said space, interfering said return radiation with reference laser radiation to produce an interference pattern on a two dimensional detector array to produce a hologram containing information about the target and about the media and return path between the target and the hologram to thereby store a two dimensional array of electronic signals representing said hologram, transferring said array of signals from said two-dimensional detector array through a real time electronic hologram processor, thereafter imposing the said processed array of electronic signals on a spatial light modulator, and reading out the hologram on said spatial light modulator by interacting a second laser beam with said spatial light modulator hologram to direct a conjugate beam of focussed laser radiation automatically pointed to said target as a low divergence beam which compensates for the effects encountered in passing through said media. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification