Wavefront correction for aerodynamic and atmospheric effects to an optical sensor on a high-speed flight vehicle
AssigneeRaytheon Company
InventorsSean D. Keller, David J. Knapp, Jon E. Leigh
Life of this patent
Estimating the term…
Abstract
A system and method for measurement and correction of aero-optical and aero-thermal effects to an EO/IR sensor's window/dome on a supersonic flight-vehicle. Range-gating of laser pulses measures and separates aerodynamic and atmospheric effects. Separate control algorithms and control loops at different update rates both simplifies the control algorithms and improves overall performance. The use of a MEMS MMA having tip/tilt/piston capabilities as the deformable mirror to provide wavefront correction enhances overall performance. The corrected laser pulses may also be used to actively illuminate a target to provide both active and passive detection.
Claims18
An optical sensor for a supersonic flight vehicle in which an optical window to the sensor undergoes aero-optical and aero-thermal effects in flight, said optical-sensor comprising:
- a clock;
- a pulsed laser that emits laser pulses through the optical window with timing codes referenced to the clock;
- a wavefront sensor referenced to the clock to detect returning laser pulses that lie within a first time delay window to measure the aero-optical and aero-thermal effects on or just in front of the optical window and to exclude atmospheric effects beyond the optical window, wherein aero-optical effects are caused by fluctuations of a refractive index of the optical window due to temperature and pressure differences around the optical window and aero-thermal effects are caused by heating of the optical window;
- an optical detector;
- an optical path that couples light received through the optical window onto the optical detector;
- and
- a deformable mirror positioned in the optical path, said deformable mirror responsive to command signals to piston orthogonal to the plane of the mirror to correct a wavefront of the received light for the measured aero-optical and aero-thermal effects.
An optical sensor for a supersonic flight vehicle in which an optical window to the sensor undergoes aero-optical and aero-thermal effects in flight, said optical-sensor comprising:
- one or more optical detectors;
- an optical path that couples light from a target returned through the optical window onto the optical detector;
- a clock;
- a laser that emits laser pulses with timing codes referenced to the clock;
- a beam combiner in the optical path that combines the laser pulses to propagate in the optical path through the optical window;
- a beam splitter to split off a portion of returning laser pulses;
- a wavefront sensor referenced to the clock to detect returning laser pulses that lie within a first time delay window to measure the aero-optical and aero-thermal effects on or just in front of the optical window and a second time delay window to measure atmospheric effects to a target, said second time delay window having a longer time duration than said first time delay window corresponding to longer round-trip times for the laser pulses;
- and
- a deformable mirror positioned in the optical path upstream of the wavefront sensor and the laser, said deformable mirror responsive to command signals to piston orthogonal to the plane of the mirror to correct a wavefront of the emitted laser pulses and to correct a wavefront of the returned laser pulses and to correct received passive light for the measured aero-optical and aero-thermal effects and atmospheric effects,
- wherein the one or more optical detectors are configured to sense both the wavefront corrected returned laser pulses and wavefront corrected received passive light to form active and passive images of the target.
An optical sensor for a supersonic flight vehicle in which an optical window to the sensor undergoes aero-optical and aero-thermal effects in flight, said optical-sensor comprising:
- a pulsed laser that emits laser pulses through the optical window with timing codes;
- a wavefront sensor referenced to a clock to detect returning laser pulses that lie within a first time delay window to measure the aero-optical and aero-thermal effects on or just in front of the optical window and to exclude atmospheric effects beyond the optical window;
- an optical detector;
- an optical path that couples light received through the optical window onto the optical detector;
- a Micro-Electro-Mechanical System (MEMS) Micro-Mirror Array (MMA) positioned in the optical path, said MMA comprising a plurality of mirrors independently responsive to command signals to tip and tilt about first and second axes, respectively, and to piston in translation along a third axis in three degrees-of-freedom (3DOF) to correct a wavefront of the received light for the aero-optical and aero-thermal effects measured by the optical detector.
Dependencies are inferred from the claim text.