Patent ID: 8076624
Filing Date: 2011-12-13
Classification: F41H,G01J,G02B

Abstract:
1. An electro-optical pre-compensating system for forming a near diffraction limited size beacon at a non-cooperative target, the system comprising: A) a near diffraction limited beacon-to-target transmission path comprising; a) a pulsed partially coherent laser beam; b) a steering mirror(s); c) a chromatic filter; d) one or more relay off-axis parabolic mirrors; e) a polarizing plate beam splitter; f) wherein the pulsed partially coherent laser beam is directed through the steering mirror(s), the chromatic filter and the one or more relay off-axis parabolic mirrors to the polarizing beam splitter which functions to direct a majority of the pulsed partially coherent laser beam through the beacon-to-target transmission path; g) a removable quarter waveplate; h) a corner cube array; i) wherein the polarizing beam splitter directs a small fraction of the pulsed partially coherent laser beam to a wavefront sensor via the removable quarter waveplate and the corner cube array thereby functioning to align and boresight the pulsed partially coherent laser beam; j) a phase correction device; k) wherein the majority of pulsed partially coherent laser beam goes to the phase correction device functioning to pre-correct the majority pulsed partially coherent laser beam for turbulence; l) a quarter waveplate; m) wherein the majority pulsed partially coherent laser beam then passes through the quarter waveplate functioning to convert the majority pulsed partially coherent laser beam from linear to a circular polarization; n) an off-axis parabolic mirror(s); o) wherein the majority pulsed partially coherent laser beam then passes through the off-axis parabolic mirrors functioning to relay the majority pulsed partially coherent laser beam to one of the steering mirrors; p) wherein the majority of the pulsed partially coherent laser beam then passes through a turbulent medium in the beacon-to-target transmission path; q) wherein the steering mirrors direct the majority pulsed partially coherent laser beam to the target through a telescope secondary and primary mirror and through the turbulent medium; B) a target beam reflection path comprising; a) a reflected pulsed partially coherent laser beam; b) wherein the reflected pulsed partially coherent laser beam is relayed back through the transmission path; c) wherein the reflected pulsed partially coherent laser beam is converted back to linear polarization by the removable quarter wave plate; d) wherein the a reflected pulsed partially coherent laser beam is then directed through the polarizing beam splitter and into the wavefront sensor; e) wherein the wavefront sensor using an optical rely and off-axis parabolic mirrors direct the reflected pulsed partially coherent laser beam through an intensity beam splitter to provide one sample of the reflected pulsed partially coherent laser beam to a high speed detector; f) wherein the high speed detector is configured to have a detector size about equal to the diffraction limited beacon; g) wherein the remainder of the reflected pulsed partially coherent laser beam passes through a custom filter functioning to rotate the polarization by 90 degrees; h) and wherein the custom filter is co-aligned to map the center of the custom filter to the center of the high speed detector functioning to create an interference pattern; i) wherein the interference pattern is directed to an assembly of the quarter wave plate aligned to the crystal axis of the custom filter, half wave plates, polarizing beam splitters and flat mirrors functioning to direct two complimentary interference patterns to a detector array; j) wherein the high speed detector and the detector array are then synchronized with the reflected pulsed partially coherent laser beam so that they integrate forming only one return beam from the target; k) wherein the high speed detector functions to control a steering mirror of the phase correction device using a multi-dither or stochastic parallel gradient descent technique; l) wherein the intensity patterns on the detector array are differenced functioning to produce a signal proportional to the gradient of a local fringe intensity; m) wherein the a plurality of signals mapping one to one to the correction channels of the phase correction device are used to control the phase correction device; n) wherein a passive or broad illumination of the target is sampled by a chromatic beam splitter, focused by an achromatic lens onto an imaging/tracking camera functioning to gather data to control the steering mirrors; and o) wherein the above described transmission and reflection paths result in pre-compensation of the pulsed partially coherent laser beam functioning to keep the laser beam pointed at the target.