United States of America as Represented by the Secretary of the Air Force

Tau Technologies, LLC

Richard A Carreras

Dennis C Duneman

James M Wilkes

Dan K Marker

James R Rotge

Mark G Baciak

Morton B Jenks

Elinor L Coates

Sami Ali Shakir

Janet S Fender

Salvatore J Cusumano

Robert I Suizu

Sergio Restaino

Patricia J Wallentine

Gordon D Love

David G Haralson

The present invention is a method for real-time predictive laser beam propagation through various atmospheric conditions and over predetermined distances. The invention includes loading input parameters into an embedded control scheme of a laser system. A prediction of one or more laser beam parameters is generated and a computational error is quantified for the generated laser beam parameters. One or more parameters for the laser system are then chosen based on the prediction and based on the quantified computational error. The chosen parameters are within a predetermined tolerance. A laser system is then built or adjusted using the one or more chosen parameters.

System and model for real-time predictive laser beam propagation

An optical quality, freestanding, compliant membrane mirror is cast with a concave parabolic shape, and includes a substrate and a reflective stress coating. The stress coating is in compression and applies a tensile shear stress to the substrate that opposes and offsets the intrinsic stress in the substrate that would otherwise decrease the concavity. The stress coating generates a force to restore the membrane mirror to its cast concave parabolic shape when an external force deforms the mirror.

Parabolic membrane mirror having a shape-restorative force

A method for fabricating an optical quality, free-standing, compliant parabolic membrane mirror using an inverted parabolic mandrel created by rotating a liquid confined to a cylindrical polymer and applying a reflective optical stress coating once the substrate has hardened. The stress coating applies a tensile force to the substrate that offsets the stress in the substrate that would otherwise decrease the convexity, and also generates a force to restore the membrane mirror to its original convex parabolic shape when the mirror is deformed by an external force.

Method of centrifugally casting a parabolic membrane mirror having a shape-restorative force

A membrane mirror having an optical quality spherical shape maintained by differential pressure takes a near parabolic shape when a plunger-induced displacement of the central area of the mirror is introduced. The focal length can be adjusted by varying the differential pressure.

Plunger controlled, near-parabolic optical membrane mirror

A thin membrane is mounted on an optically flat circular outer ring and stretched over a smaller optically flat circular inner ring. Differential pressure is applied to the annulus formed between the inner and outer rings to prestrain the membrane and separately applied to the inner ring where the mirror figure will be produced. The inner ring has a doubly curved top surface and is optically fiat so that the membrane can freely move across the inner ring as incremental stress is applied via the annulus. A calculated combination of annulus stress and differential pressure on the inner ring produces an optical quality mirror figure in the inner ring area.

Active edge controlled optical quality membrane mirror

Large space-based optical systems are expected to produce optical beams with large wavefront phase aberrations due to their size, weight limitations, optical misaligments and primary mirror imperfections. The present invention combines a phase diversity wavefront sensor with a real-time programmable two-dimensional array of liquid crystal variable retarders for wavefront correction.

Liquid crystal active optics correction for large space based optical

A system and method for large angle off-axis steering of the composite beam from a phased array telescope system.

Large angle off-axis beam steering of a phased telescope array

In an optically phased array of multiple laser telescopes, the phasing between the telescopes is accomplished by sampling adjacent outgoing wavefronts. The two samples of each wavefront are then combined to form an interference pattern on a camera. This image is then converted to digital signals, employing an error signal representative of the phase difference. It is necessary that the telescopes be pointing in the same direction. This is assured by having each telescope associated with an optical sensor which produces an X or Y tilt error. The X or Y tilt error is corrected by the optical component referred to as the optical path difference adjustor (OPDA). A signal processing circuit is disclosed which receives X and Y tilt error signals, as well as phase error signals, and produces therefrom drive signals which correct and drive the OPDA in an array of multiple laser telescopes.

Axis separator electronic translator

The microcomputer controlled image processor receives an interference pattern of samples of pairs of transmitted laser beams from a charge couple device (CCD) camera. The present invention then calculates an optical path difference between each pair of beams using: an analog amplifier, an analog-to-digital (A/D) converter, a multiple accumulator controller, a programmable read-only-memory (PROM), a microcomputer, and a random access memory (RAM). The analog amplifier and A/D converter amplify and convert to digital the interference pattern received from the CCD camera. The multiple accumulator controller (MAC) receives the digital camera signal from the A/D converter, and adds correction factors for the non-linearities in the CCD camera. The PROM stores these correction factors, and supplies them to the multiple accumulator controller when needed. The random access memory receives and stores the corrected data from the multiple accumulator controller, and supplies the data to the microcomputer. The microcomputer receives the corrected digital interference pattern from the random access memory, and applies two algorithms to the data to yield estimates of the optical path difference between the two sampled laser beams. The optical path difference (OPD) is a measure of adjustment in the optical path lengths of the two sampled laser beams. When this OPD value is supplied to the laser transmitter, a correcting means can adjust the length of the optical paths of one or both of the sampled laser beams to bring them in phase with each other.

Microcomputer controlled image processor

A plurality of telescopes provide output return signals which are applied both directly and in sampled form to a photo-detector cell. The detected signals from the photo-detector will represent the constant and transient errors of the telescope system. A low pass filter insures that the tracker provides only the constant or D.C. component of the error, while a high pass filter insures that the existing measuring devices for each telescope beam provide only the transient or A.C. component of the error. The A.C. and D.C. error signals are summed together with the appropriate applied gains on each channel such that the sum reconstructs the original telescope position error with good fidelity.

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Albuquerque, NM, United States of America

Richard A Carreras