Hughes Aircraft Company

Raytheon Company

Hughes Electronics Corporation

Rensselaer Polytechnic Institute

Gerard L Rafanelli

Susan B Mount

Mark J Rehfield

Brent L Ellerbroek

Stephen K Johnson

Lacy G Cook

Partha S Dutta

Claudio Parazzoli

Robert Zwirn

Mitchell B Haeri

Eric B Jensen

Bobby R Hunt

Marilyn A Sperka

Philip J Sementilli

Albert M Bisbee

James F Montgomery

Methods, systems, and photovoltaic devices converting broad spectrum incoherent optical power into electrical power by utilizing nonlinear multi-photon absorption and optionally enhanced by the application of magnetic fields, electric fields, or both during the power conversion process.

Photovoltaic device for generating electrical power using nonlinear multi-photon absorption of incoherent radiation

A spinning strip aperture imaging radiometer sensor system and data processing methods for detecting moving objects derived from a plurality of image frames acquired by a strip aperture imaging sensor. A moving object in any individual image frame results in a motion smear signature in the total synthesized image. The motion smear signature is processed to detect the moving objects. One embodiment of the system comprises a rotating strip aperture telescope, a two dimensional detector array that detects images in the telescope's focal plane, a rotation compensation device that prevents rotational smear during integration time of detectors of the array, a signal processor that records a plurality of image frames of a scene imaged by the telescope as it rotates around its optical axis, and that implements method(s) for detecting the moving objects present in the recorded images. A hierarchy of moving object detection processors and methods,is disclosed that includes spatial, temporal, spatial frequency, and temporal frequency domain detection processors, and is compatible with multi-spectral background rejection techniques. Selection of the appropriate processing procedure and method depends upon the scenario, and the effective signal to noise ratio characteristics of the moving object.

Moving object and transient event detection using rotation strip aperture image measurements

A spinning strip aperture imaging radiometer sensor system and data processing method for synthesizing a super-resolved scene estimate (super-resolved scene) from a plurality of image frames acquired by the strip aperture imaging sensor system. One embodiment of the imaging system comprises a rotating strip aperture wide field of view telescope, a two dimensional detector array for detecting images in the focal plane of the telescope, rotation compensation apparatus for preventing rotational smear during the integration time of the detectors, a signal processor for recording a plurality of image frames of a scene that is imaged by the telescope as it rotates around its optical axis, and an estimation processor employing the present method for synthesizing the super-resolved scene estimate from the recorded images. The super-resolved image synthesis method uses a plurality of rotating strip aperture measurements within the strip aperture passband and within the passband of an equivalent bandlimited synthesized full circular aperture to estimate the spatial frequency information outside the total measurement passband, and/or outside the passband of the equivalent bandlimited synthesized full circular aperture, as well as within the equivalent bandlimited passband. Knowledge of the spatial response function of the strip aperture, the spatial response function of the detector array, noise statistics, and the temporal registrations of each of the recorded strip aperture images permits synthesis of the super-resolved full aperture image by the sensor system and image synthesis method. The super-resolved image synthesis method may be employed in the spatial domain, the spatial frequency domain, or both.

Super-resolved full aperture scene synthesis using rotating strip

An extended scene wavefront sensing apparatus and procedure that separates (deconvolves) scene effects from wavefront errors of an optical or similar system. The present wavefront sensing apparatus and procedure uses a point source wavefront slope sensor in scene scanning mode and estimates wavefront errors by using a cross-correlation or cross-coherence procedure that operates on the outputs of the point source wavefront slope sensor. A signal processing procedure employed by the point source wavefront slope sensor provides output signals corresponding to wavefront slopes at forward optics pupil locations geometrically projected to the location of the transmission and reflection measurement plane detector pairs. During the scanning process, each of the detector pairs (equivalent to a subaperture) measures the effects of the local unchanging wavefront error in the forward optical system and temporal variations due to the scanning scene. By cross correlating or cross-cohering each detector pair's temporal difference with differences from selected reference detector pairs, the scene induced variations in the measurement are eliminated, thereby leaving the stationary wavefront error component of the measurement. The lead/lag time in the temporal differences output between detector pairs and reference detector pairs are then used to estimate the wavefront slope differences between equivalent subapertures. The wavefront slope differences are used in a reconstructor to generate wavefront errors or wavefront slope errors, except for an unobservable global tilt.

Wavefront error estimation derived from observation of arbitrary unknown

Disclosed is a method and apparatus for reducing or eliminating the speckle intensity distribution of an imaging and/or tracking system The benefits of utilizing a highly coherent source (12) as an imaging and tracking system are well known. However, such a coherent source (12) provides a speckle intensity distribution which reduces the effective resolution capability of the imaging system. This invention takes a coherent beam of light (14) and impinges it into a Raman cell (16) to obtain a broad spectral bandwidth beam of light having additional side wavelengths other than the original wavelength. In addition, this invention provides a means to improve the beam quality of all of the Raman lines. Therefore, a composite beam having broad spectral bandwidth composed of individual spectral lines having good beam quality is generated. As a result of the broad spectral bandwidth, images formed from targets illuminated by such a composite beam are substantially free of speckle intensity variations.

Speckle suppression illuminator

A spinning strip aperture imaging radiometer sensor system and data processing method that is capable of synthesizing full circular aperture images from a plurality of image frames acquired by the strip aperture imaging sensor. One embodiment of the imaging system comprises a rotating strip aperture wide field of view telescope, a two dimensional detector array used to detect images in the telescope's focal plane, a rotation compensation device used to prevent rotational smear during the integration time of the detectors, a signal processor used to record a plurality of image frames of a target scene that is imaged by the telescope as it rotates around its optical axis, and a signal processor and method used to synthesize the full circular aperture image from the recorded images. The operation of the full aperture image synthesis method hinges upon the ability of the rotating strip aperture to measure all of the spatial frequencies contained in a full circular aperture image measurement. Having knowledge of the strip apertures' spatial frequency passband, and the temporal registrations of each of the recorded strip aperture images permits synthesis of the full aperture image by the sensor system and image synthesis method. Image synthesis may be accomplished in the spatial or spatial frequency domains. General and illustrative examples of the image synthesis procedure and first order noise performance predictions are described. A general form of the invention utilizes two dimensional spatial frequency information to greatly reduce the line of sight stability requirements of the telescope.

Full aperture image synthesis using rotating strip aperture image

Relative piston misalignments between segments of a multisegment optical system, such as a segmented primary mirror, are reduced by a method in which elements of an arbitrary unknown extended scene image carried by an input beam are eliminated from the beam's error information in performing an error calculation. After appropriately processing the beam with the specialized sensor elements, spatial frequency domain representations of a variety of optical images are obtained which correspond to both individual segments, and to multiple combinations of segments of the optical system; each combination is preferably composed of two individual segments. The spatial frequency domain representations of the individual segments are then subtracted from the representations of the segment combinations to obtain spatial frequency domain functions for the combinations. These in turn are compared by a cross-coherence technique to derive spatial domain differences of piston differences misalignments between the combinations, from which the piston errors between individual segments can be calculated via a reconstruction matrix. The calculated piston errors are then used to make a compensating adjustment to the piston positions of the individual segments in the optical processing element.

Piston error estimation method for segmented aperture optical systems

A laser source 28 and curvature matching optics 30 cooperate to generate a probe beam 32 having a generally Gaussian phase front with a given radius of curvature. The probe beam is reflected off of the surface of a primary mirror 12 and the differences, if any, between the radii of curvature of the probe beam 32 and mirror surface is detected by detector array 38. Suitable feedback circuitry can be employed to drive the actuators of segments 16-22 to provide the mirror 12 with the desired figure.

Method and apparatus for sensing the figure of optical elements

An electronic focus correction system is provided. The invention (10) is adapted to correct focus aberrations in an electronic imaging system which provides electrical signals representative of a scene of image data. The invention includes a memory (12) for providing sets of weighting coefficients and a two dimensional convolver (18) for multiplying the input electrical signals corresponding to a window in and around each pixel of image data by a set of the weighting coefficients. The two dimensional convolved (18) assigns to each pixel a value equal to the sum of the products of the coefficients times the electrical signals within each window to provide a plurality of weighted output signals. The output signals constitute a corrected image. A controller (20), responsive to the output of the two dimensional convolver (18), is provided to measure the figure of merit for the corrected image. Coefficient control logic (108) responsive to the output of the controller (20) is included for providing signals to select an alternate set of coefficients for multiplication with the input signals to thereby provide a corrected image with an optimized figure of merit. In a more specific embodiment, model adjustment logic (112) is included for changing the power spectral density of the corrected image.

Electronic focus correction by signal convolution

An interferometric spectrometer (20) for determining two-dimensional positional and spectral information of two-dimensional light sources (26) is disclosed. The spectrometer (20) includes a mechanism (28) for splitting a beam source (24) into two beam components (30) and (32). A mechanism (34) and (36) for focusing and centering the pair of beam components (30) and (32) is positioned in the line of projection of the beam components (30) and (32). A mechanism (38) and (40) for reflecting the pair of beam components (30) and (32) is positioned in the line of projection of the two beam components (30) and (32). A detector mechanism (42) for detecting the beam components (30) and (32) is positioned in the line of projection of the two beam components (30) and (32). A mechanism (44) for determining spatial and spectral information of the source (26) is associated with the detector mechanism (42 ). Also disclosed is a method of determining spatial and spectral information of a light source utilizing the spectrometer.

Growing community of inventors

Fountain Valley, CA, United States of America

Gerard L Rafanelli