Santa Barbara Research Center

Lahaye; Peter

Hughes Aircraft Company

Hughes Electronics Corporation

Arthur H Hardy, Jr

Leland V Gardner

John E Clement

Mark E Preiser

James S Lee

William C Schubert

William C Holzer

Stephen W Palmer

An optical coupler for coupling energy from a laser diode bar is disclosed. The coupler includes multiple rectangular optical fibers that each have a cylindrical lens which is an integral part of each fiber end. The fiber ends are held in a fixed spatial relationship by a retainer. In one coupler embodiment, each fiber end is shaped to define the cylindrical lens. In another coupler embodiment, each fiber end carries a lens shaped from an optical medium. Methods of making the couplers are also disclosed.

Method and apparatus for coupling laser diode beams to optical fibers

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

Object detection apparatus (40) inlcudes a transmitter assembly (44) and a receiver assembly (10). The receiver assembly includes a receiver element (12) having an input aperture (16) for receiving electromagnetic radiation reflecting from an object. The receiver element further includes an output aperture (24) and a curved surface (22) disposed relative to the input aperture for reflecting substantially all electromagnetic radiation (A,B,C) reflecting from an object at a range in excess of a range of interest, to the output aperture. A first radiation detector (14) is disposed at the output aperture for receiving the object radiation reflected thereto and for generating a first electrical signal. A second radiation detector (30) is disposed at a location upon the receiver assembly for receiving object radiation reflected thereto that reflects from an object at a range that is within the range of interest. The apparatus further includes circuitry (32, 34, 35, 36, 37, 38, 39) for combining the first electrical signal with the second electrical signal for substantially eliminating a component of the first electrical signal that is due to electromagnetic radiation reflecting from an object within the range of interest.

Target detector capable of rejecting close-in objects

The range (R) to a target (12) is precisely determined by controlling the amplitude of the carrier before modulation using a feedback signal derived from the detected return. The amplitude of the carrier is adjusted (40) so that all return pulses have a constant amplitude. Hence, for any given range, all return pulses cross threshold at the same time, thereby eliminating ranging errors due to phase distortion. The return pulses are threshold detected (54) and converted to a CW signal, which is then down converted. The phase information, which is indicative of target range, is preserved in the down conversion process and is extracted by phase comparison (72) with a reference signal to determine the target range.

Precision ranging system

A semiconductor laser chip having one or more lasing junctions is mounted on one side of a thin sheet of thermally conductive material opposite to a second semiconductor laser chip of the same construction mounted on the opposite side. The thin sheet of material allows the emitting facets of the semiconductor laser chips to be placed in close proximity for coupling into the end of an optical fiber or other use. Made of hardened copper or other suitable material, the thin sheet of material serves as a heat conducting path between the semiconductor laser chips and a heat sink. Different configurations may utilize different shapes for the thin sheet of material; the thin sheet may have parallel opposing sides or opposing sides that are at an angle with respect to one another.

Increased intensity laser diode source configuration

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 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

Instrument for tattooing

A multi-channel adaptive threshold circuit usable to extract affirmative detection impulses from a plurality of detection circuits each having a different background noise level. The circuit comprises a plurality of analogous detection circuits whose outputs are coupled in parallel between a threshold circuit and threshold activation device such as a switch which grounds all outputs when in the ON position. The input to each detection circuit, which is a composite of sporadic affirmative return pulses and continuous background noise, is passed through a unidirectional conducting device, such as a base-to-emitter junction of a transistor, to charge a capacitor to a value which is a function of the continuous background noise. When the threshold activation device is turned off, the output plate of the capacitor of each detection circuit is applied to a fixed threshold circuit. Since a large value resistor coupled between the input plate and ground prevents rapid discharge of the capacitor, the potential across the plates remains substantially constant. The slow discharge results in a higher voltage on the input plate which causes the base-to-emitter junction to be back biased and thus nonconductive for almost all detection signal levels except high voltage pulses which are likely to indicate a positive detection return. Thus, each channel independently sets its own threshold level which is determined by the additional charge due to background noise across the capacitor just before the threshold activation switch is turned off. The signal threshold level in each detection circuit is then the sum of the additional potential across the capacitor of that detection circuit and the fixed threshold voltage established by the threshold circuit.

Growing community of inventors

Santa Barbara, CA, United States of America

Arthur H Hardy, Jr