Raytheon Company

Eric Rogala

Gerald P Uyeno

Sean D Keller

Benn H Gleason

Craig O Shott

Mark K Lange

Garret A Odom

Jon E Leigh

Vanessa Reyna

Zachary D Barker

David James Knapp

Andrew W Dutton

The design of an existing air-to-air missile seeker is adapted to new missions that require both active laser illumination and detection (passive or active) capabilities. The gimbal is used to point the laser beam to a desired location in a transmit FOR. This approach minimizes the size, weight and power of the sensor because only a small portion of the transmit FOR is illuminated at any instant. This minimizes the laser output required, which reduces the power to operate the laser and the power to maintain the laser at operating temperature. In existing seekers, the gimbal points the detector in the desired direction to expand its FOR. To address the limitations of coupling the laser beam into the gimbaled optical system, the gimbal cannot perform the steering function for the detector. Instead, a staring detector receives light through an off-gimbal aperture within a fixed receive FOR that overlaps the transmit FOR.

Optical sensor with dual-axis gimballed transmitter and staring detector

An image polarimeter includes a MEMS MMA divided into two or more segments in which the mirrors in each segment are provided with a polarizer of a given polarization. The mirrors in each segment are tipped and tilted to steer polarized light onto different portions of an optical detector. In certain configurations the mirrors may also be pistoned to reduce aberrations. Each frame that is read out from the detector includes two or more distinct component polarized images having different polarizations P0, P2, . . . of the same scene to fully characterize the polarization properties of the scene. Since the mirrors only tip/tilt/piston in the dead period between frames, no components are moving during image acquisition and co-registration of the component polarized images is simple. The number of segments and the different polarizations may be selected to implement Jones calculus, Mueller calculus and Stokes parameters or other polarimetry techniques.

Image polarimeter using a micro-electro-mechanical system (MEMS) micro-mirror array (MMA)

A multiple FOV optical sensor includes a primary mirror having first and second rings of differing curvature to collect light from an object within different FOV. A secondary mirror includes a MEMS MMA in which the mirrors tip and tilt in 2 DOF or add piston in 3 DOF to (I) reflect light from the first ring within the first FOV that is focused at an imaging plane coincident with an imaging detector to form a focused image of the object at the imaging detector or (II) reflect light from the second ring within the second FOV onto the imaging detector (either focused to form a focused image or defocused to form a blurred spot). The MEMS MMA may be configured to alternate between (I) and (II) or to perform both (I) and (II) at the same time with the different FOV either overlapped or spatially separated on the detector. The sensor may be configured as an all-passive sensor, a dual-mode sensor or a hybrid of the two.

Multiple field-of-view (FOV) optical sensor using a micro-electro-mechanical system (MEMS) micro- mirror array (MMA)

An optical scanning system includes one or more Micro-Electro-Mechanical System (MEMS) Micro-Mirror Arrays (MMAs) used to scan a field-of-view (FOV) over a field-of-regard (FOR). The MEMS MMA is configured such that optical radiation from each point in the FOV does not land on or originate from out-of-phase mirror segments and a diffraction limited resolution of the optical system is limited by the size of the entrance pupil and not by the size of individual mirrors.

Optical scanning system using micro-electro-mechanical system (mems) micro-mirror arrays (MMAs)

Optical sensors and particularly gimbaled optical sensors transmit an active signal at a given wavelength(s) and receive passive signals over a range of wavelengths and the active signal in a common aperture. The sensor includes a Tx/Rx Aperture Sharing Element (ASE) configured with a center region that couples the active signal to the telescope for transmission and an annular region that couples the passive emissions and the returned active signal to the detector. A filter wheel may be positioned behind the ASE to present separate passive and active images to the detector. These optical sensors may, for example, be used with guided munitions or autonomous vehicles.

Optical sensor with Tx/Rx aperture sharing element (ASE) for processing passive and active signals

A zoom system includes a collection optic Land a reflective Fresnel Lens Lhaving a variable focal length. The reflective Fresnel Lens Lis implemented with a MEMS MMA in which the mirrors tip, tilt and piston form and alter the reflective Fresnel Lens to focus light at a common focal point to set the variable focal length f2, hence the magnification M. In different embodiments, the zoom system may be configured to be 'focal' or “afocal”. In the focal system, both Land Lare fixed such that the system affects the net convergence or divergence of the magnified beam. In an afocal system, a mechanism is used to translate Lto maintain a separation between Land Lof d=f1+f2 as f2 is varied to change the magnification M.

Optical zoom system using an adjustable reflective fresnel lens implemented with a micro-electro-mechanical system (MEMs) micro-mirror array (MMA)

Optical sensors and particularly gimbaled optical sensors transmit an active signal at a given wavelength and receive passive signals over a range of wavelengths while controlling pointing without benefit of measuring and locating the active signal return. The sensor includes a Tx/Rx Aperture Sharing Element (ASE) is configured to block the received active signal (e.g. reflections off a target in a scene) and process only the passive emissions. These optical sensors may, for example, be used with guided munitions or autonomous vehicles.

Optical sensor with Tx/Rx aperture sharing element (ASE) to block detection of the received active signal

A beam steering architecture for an optical sensor is based upon a pair of Micro-Electro-Mechanical System (MEMS) Micro-Mirror Arrays (MMAs) and a fold mirror. The MEMS MMAs scan both primary and secondary FOR providing considerable flexibility to scan a scene to provide not only active imaging (to supplement passive imaging) but also simultaneously allowing for other optical functions such as establishing a communications link, providing an optical transmit beam for another detection platform or determining a range to target. A special class of MEMS MMAs that provides a 'piston' capability in which the individual mirrors may translate enables a suite of optical functions to 'shape' the optical transmit beam.

Optical sensor with micro-electro-mechanical system (MEMS) micro-mirror array (MMA) steering of the optical transmit beam

An optical sensor uses a MEMS MMA to scan a narrow laser beam over a transmit FOR to provide active illumination and to correct the beam profile (e.g., collimate the beam, reduce chromatic aberrations, correct the beam profile or wavefront). A staring detector senses light within a receive FOR that at least partially overlaps the transmit FOR. By completely eliminating the dual-axis gimbal, this sensor architecture greatly reduces the volume and weight of the optical sensor while avoiding the deficiencies of known systems associated with either fiber or free-space coupling of the laser beam into an existing receiver.

Optical sensor with MEMS MMA steered transmitter and staring detector

Small angle optical beam steering is performed using a Micro-Electro-Mechanical System (MEMS) Micro-Mirror Array (MMA) that minimizes diffraction for a specified steering angle, Generally speaking, this is accomplished with a MEMS MMA that exhibits a 'piston' capability to translate individual mirrors in addition to the tip and tilt capabilities. Adjacent mirrors can be tipped/tilted to the specified steering angle and then translated by a requisite amount to approximate a continuous surface. For a specified steering angle, the MEMS MMA is partitioned into one or more sections with each section including the maximum number of mirrors that can be grouped together and actuated to approximate a continuous surface given a maximum translation z. As a result, the only edge discontinuities exist between adjacent sections thereby minimizing distortion for a given steering angle.

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Tucson, AZ, United States of America

Eric Rogala