Santa Barbara Research Center

US Government As Represented by the Secretary of the Army

Raytheon Company

Hughes Aircraft Company

Hughes Electronics Corporation

Leland V Gardner

Arthur H Hardy, Jr

Paul S Sugino

Methods and apparatus are disclosed for concentrating the energy of a laser diode beam by imaging a first numerical aperture of the beam in one beam plane to a reduced numerical aperture at a focal plane, and by guiding the beam between reflective boundaries to maintain the value of a lesser second numerical aperture in another beam plane at the focal plane. The reduced numerical aperture in the first plane optimally matches the second numerical aperture in the second plane so that the energy can be received into the entrance end of an optical fiber whose numerical aperture also matches the second numerical aperture. The area of this fiber preferably matches that of the image at the focal plane. A coupler that guides the beam to its focal plane preferably utilizes an imaging element, e.g., a cylindrical lens or a cylindrical elliptical mirror, and a pair of spaced reflective walls. The exit ends of a plurality of fibers that are illuminated by respective beams can be closely packed into any desired pattern which can be fractionally magnified by a relay lens into a very concentrated energy pattern. If desired, this final image may be fed into a single optical fiber for passage through remote or convoluted optical paths.

Method and apparatus for concentrating and combining the energy of

Methods and apparatus are disclosed for concentrating the energy of laser diode beams by imaging them to obtain a superimposed image and a combined numerical aperture at a focal plane and by guiding them between reflective boundaries to maintain a lesser second numerical aperture at the focal plane. The combined numerical aperture preferably matches the second numerical aperture so that the energy can be received into the entrance end of optical fibers whose numerical apertures also match the second numerical aperture. A described embodiment utilizes collimating lenses and an off-axis parabolic reflector. The exit ends of the optical fibers can be grouped and fractionally magnified into a concentrated energy pattern. The final image can be imposed into a single optical fiber for passage along remote or convoluted optical paths.

Method and apparatus for concentrating the energy of laser diode beams

An improved apparatus is disclosed for reliably and unambiguously sensing the angle of arrival of an electromagnetic radiation beam by a remote source. A sensor assembly 2 receives, through an optical window 22, the incident beam which is directed toward first and second detectors 10, 12 by a gradient beam splitter 24. The beam splitter 24 has a gradient of reference and transmittance deposited along one surface which is correlated to the angle of arrival of the radiation. The first detector 10 and second detector 12 receive a portion of the incident beam energy by reflection and transmission respectively from the beamsplitter 24. The ratio of a difference to a sum of the detector responses to the received energy is thereby also correlated with the angle of arrival. Atmospheric scintillation, which causes shifting concentrations of energy in clusters or 'scintels' within the beam, is compensated by the action of gradient opaque stripes of the beam splitter 24 which divide the beam by a constant factor irrespective of the energy distribution. Thus when the ratio of difference to sum of the responsee to the divided beam by the first and second detector 10, 12 is taken, the correlation with angle of arrival is not affected by the shifting energy.

Response ratioing angle of arrival sensor that is responsive to

A compact and efficient two direction of arrival system which is responsive over a large incident solid angle. The system is operative to use relatively few detectors, simple and inexpensive optics in a small assembly, and a very wide field coverage.

Two directional angle of arrival system

A proximity sensing system and signal processing method are disclosed for detecting target objects from a movable vehicle while protecting against false target detection due to the presence of fog, clouds, or other aerosols. One or more target detectors are alternately disposed adjacent to one or more guard detectors so the edges of the fields of view are immediately adjacent. A collimated laser beam is projected away from the vehicle by a transmitter along an axis which intersects at an angle with the adjacent fields of view defining active areas in which the beam will be reflected from objects. Signals generated from any beam reflections to a target detector are made positive while signals generated by any beam reflections to a guard detector are made negative with respect to a threshold reference. The signals are summed in a differential amplifier and the resultant signal presented to a digital comparator. Signals produced by reflections from a solid object in a target detector field of view causing the comparator output to exceed a detection voltage threshold, indicate a true target. Signals produced by reflections of the beam into the target detector(s) and guard detector(s), from clouds or fog even if as strong as a solid object, are maintained below the detection voltage threshold. Large specular reflections, for example, from water, produce a similar result. The summing action steepens the slope of the summed signal produced when a target image moves onto the edge of a target detector element causing targets to be detected very near the edge of a target dectector active area, hence at near-constant range, irrespective of target reflectance.

Multiple detector fog suppression and edge enhancement

An optical projection apparatus is disclosed for generating a planar light beam of substantially uniform intensity from a nonplanar multi-element light source 10 projecting a beam having a generally Gaussian intensity distribution. Light from the source 10 passes through an optical integrator rod 52 having a faceted entrance face 54 and a spherical exit face 50. The spherical exit face 50 is designed to move the image 42 of the rod entrance face that would otherwise be created between the objective lens 14 and output plane 40 to a position 48 between the lens 14 and the exit face 50. In such manner, localized hot spots which may be created by the image 42 of the entrance face are substantially eliminated thereby ensuring that the entire length of the beam between the lens 14 and output plane 40 has a substantially uniform intensity distribution.

Intermediate range intensity modification of gaussian beam using optical

An optic receiver capable of detecting the angle of incidence of optical energy in a plurality of fields of view relative to an airborne frame of reference. Incoming rays are reflected by surfaces arranged at predetermined angles relative to an input aperture so as to reflect rays in predetermined fields of view into parallelism with the receiver axis and ultimately to a line image at an output aperture. Power distribution along the line image varies with the azimuth of the target reflection. Computation of target azimuth from the power distribution along the line image is facilitated by photodetectors mounted on the element and associated electronic circuitry.

Apparatus for reception and radiation of electromagnetic energy in

An optic receiver capable of detecting the angle of incidence of optical energy relative to an airborne frame of reference. Incoming reflected rays are reflected by a one piece detector element into a line image. Power distribution along the line image varies with the azimuth of the target. Computation of target azimuth from the power distribution along the line image is facilitated by photodetectors mounted on this element and associated electronic circuitry.

Apparatus for determining of angle of incidence of electromagnetic energy

An optical proximity fuze is disclosed which has an improved response at se range with respect to a target. The fuze comprises a source of infrared radiation or visible light which is projected toward the target, and a receiver or detector which responds to radiation reflected from the target. An opaque field stop in front of the detector comprises multiple apertures for permitting only selected portions of the reflected radiation to reach the detector. The use of multiple apertures, rather than a singular large aperture, improves short range response of the fuze without increasing sensitivity of the fuze to aerosols.

Growing community of inventors

Buellton, CA, United States of America

Leland V Gardner