USA As Represented by Secretary of the Navy

Other

Thomas G Giallorenzi

Joseph F Weller

William K Burns

Joel M Schnur

A Fenner Milton

James D Crowley

Henry F Taylor

Sang K Sheem

Carl A Villarruel

Alan B Tveten

Samuel J Petuchowski

George H Sigel, Jr

Paul S Lebow

Michael J Wilson

Ronald O Miles

Ronald A Andrews

Richard A Steinberg

Alfred P De Fonzo

Peter H Huang

A method and system are described for illuminating a target with a laser source with a wide-area illuminating beam. A conjugator can receive a reflected, imprinted wavefront from the target that is imprinted with effects from beam distortions and obstructions between the laser source and the target. The conjugator can then generate a hologram. A directed laser beam can then be generated to the target by reading the generated hologram with a second reference beam creating a time-reversed wavefront that can be generated with high gain. The time-reversed wavefront can retrace the path that originated from the laser source to the target, and can reverse the effects of beam distortions and obstructions. Finally, an enhanced return can be received from the target with a receiver, and a time-gating switch can be utilized that selectively selects a particular range of return wavefronts that include wavefronts that reached the target.

Time-gated image reconstruction using phase conjugation

Micro-spectral sensors and methods are presented in which a Fizeau wedge interference filter is disposed between a focal plane array and a visible scene with an increasing wedge filter dimension varying along a scan direction, where the scene is scanned along the FPA to obtain light intensity measurements of a given scene location at different times using different FPA sensor elements through different wedge filter thicknesses, and the measurements correlated to the given scene location are Fourier transform to generate spectral data for the location.

Micro-spectral sensor

A thermal dilation type optical flow sensor includes an optical heating sce for heating a flowing fluid and a sensor disposed in a downstream direction from said heating source wherein the sensor includes a probe for varying a reflected light according to the temperature of the probe, a Michelson type interferometer for measuring the temperature of the probe according to the phase of the reflected light, and a calculating device for determining the flow rate based on the temperature of the probe, the distance between the heating source and the probe, and the amount of heat produced by the heating source. In an alternative embodiment, a thermal dilation type optical flow sensor includes a reflecting probe disposed in a flowing fluid for reflecting an incident light with a phase varied according to the probe temperature, an optical heater for heating the probe with a predetermined heat, and a calculating device for calculating a flow rate based on the predetermined heat and the phase of the reflected light.

Thermal dilation fiber optical flow sensor

An improved gas sensor which optically senses a signal indication proportional to the concentration of a paramagnetic/diamagnetic gas in a gaseous mixture. In a preferred embodiment of the invention a chamber is adapted to contain a gaseous mixture to be measured for the concentration of a paramagnetic/diamagnetic gas in the mixture. An optical source provides light to a movable element coupled to the chamber. In response to the application of a magnetic field across the chamber, any paramagnetic/diamagnetic gas in the chamber causes the movable element to be displaced by a distance proportional to the concentration of the paramagnetic/diamagnetic gas in the gaseous mixture. A photodetector circuit receives light from the movable element having a characteristic indicative of the distance that the movable element was displaced. In response to such received light, the photodetector provides a signal output proportional to the concentration of the paramagnetic/diamagnetic gas in the gaseous mixture.

Optical paramagnetic/diamagnetic gas sensor

A method and apparatus for remotely activating and analyzing fiber optic ed and conformal sensor arrays using fiber optic transmission and reception with multiplexed input and output signals using optical wavelength division, electronic frequency division, or both.

All-optical towed and conformal arrays

An extended laser sensor including a laser with an opticla gain lasing medium optically coupled to an optical resonant cavity including reference and sensor arms. Optical path length variations in the sensor arm induced by an incident physical field modulate the operating parameters of the laser. The field is sensed by monitoring these modulated operating parameters.

Extended laser sensor

A coupler for coupling light from one single mode optical fiber to another. Two or more optical fibers are provided in twisted or braided adjacency so that the evanescent field of one optical fiber is coupled into at least one other fiber for dividing the power therebetween. Means are provided for coextensively supporting and encapsulating the optical fibers to stabilize and protect them under demanding environmental conditions resulting from temperature variations, physical shock and vibration.

Potting techniques for fiber optical couplers

A fiber optic interferometric physical sensor. A fiber optical Mach-Zehnder interferometer includes a sensor arm and a reference arm having different optical path lengths. A transducer coupled to the sensor arm modulates the phase of light signals passing therethrough in response to a physical quantity. The interferometer is supplied with an input optical signal which includes light components at two different wavelengths. The detected intensity of the output of the interferometer includes two components, each of which vary in relation to the physical quantity. Each output component is related to one of the two optical input wavelengths. The two output components differ in phase by an amount proportional to the path length difference between the sensor and reference arms and proportional to the wavelength difference between the light components of the input optical signal. The phase difference is adjusted such that the sensitivities of the two output components to the physical quantity are never simultaneously at a minimum. In an alternative embodiment, a single laser having a continuously variable wavelength is used with the interferometer having differing sensor and reference path lengths to achieve maximum sensitivity.

Fiber optic interferometer using two wavelengths or variable wavelength

A magnetic field sensor for detecting a magnetic field perturbation while nulling out variations in the signal caused by acoustic perturbations comprising a first and second optical fibers, an adjustable optical coupler for coupling light therebetween, a magnetic component attached to the optical coupler for exerting a mechanical force thereon proportional to a magnetic field perturbation to thereby change the degree of coupling between the fibers, and an optical detector for determining the amount of light actually being coupled between the fibers. As noted above, the system includes an acoustic circuit for nulling out the response in the detector signal due to acoustic perturbations. Two separate embodiments are disclosed. A first embodiment modulates the axial alignment of fibers in an end-to-end configuration by means of a magnetic material. A second embodiment modulates the evanescent coupling between the fibers disposed in parallel adjacency via a magnetostrictive material.

Amplitude mode magnetic sensors

A sensor for sensing conditions such as acoustic waves, temperature changes, acceleration current and magnetic fields. The sensor employs a diode laser having its cavity contained between end facets defined by partially reflective mirrors, supplemented by an external cavity formed between one of the end facets of the laser and a translatable external reflector. The reflector is position-responsive to a condition to be sensed. A change in the reflector's positions causes laser output light to be fed back through the mirror into the laser cavity with varying phase such that an increase or decrease in laser emission is created. A change of detector voltage or change in laser current provides an indication of environmental condition being sensed.

External cavity diode laser sensor

Coupling devices for SAW's, which permit switching of SAW power between cnels. Channel waveguides are laid down on or in the surface of a substrate. The waveguides have a coupling region in which they are close to each other. The input waveguide is formed from a material whose acoustic wave velocity characteristic can be changed by an external means. Various means for altering the velocity of the SAW, such as electric or optical fields, are employed by applying them to the coupling region of the input waveguide.

Active waveguide coupler for surface acoustic waves

An optical fiber sensor for detecting the presence of magnetic fields. Light carrying optical fibers are arranged in the form of a dual path interferometer wherein the separate paths define sensing and reference arms. The sensing arm is associated with magnetostrictive material for defining a sensing element which in the presence of a magnetic field undergoes dimensional changes to stretch the optical fiber to change its optical path length thus causing a detectable phase shift in light passing therethrough when compared with the same light passing through the optical fiber of the reference arm. The sensing element is isolated from thermal and acoustic perturbations thus permitting low frequency magnetic field detection.

Optical fiber magnetic field sensor with thermal and acoustic isolation

A sensing element of magnetostrictive material associated with an optical fiber of an interferometer arm defining apparatus for detecting magnetic fields. The magnetostrictive material is adhered in close co-extensive adjacency with the optical fiber and in the presence of a magnetic field undergoes responsive longitudinal dimension changes which strains the optical fiber and induces a strain related phase shift in an optically propagating beam in the fiber detectable by interferometry.

Fiber optical magnetic field sensor using magnetostrictive material

A method of improving the signal-to-noise ratio (dynamic range) in integrated optical spectrum analyzers. An integrated optical spectrum analyzer is formed with a lithium niobate (LiNbO.sub.3) substrate in its usual manner. Ions such as argon or hydrogen are implanted in the bottom and sides of the LiNbO.sub.3 which causes the substrate to absorb light at the wavelength of interest. The ion-implanted bottom and sides provide absorption with very little reflectivity and the amount of absorption is proportional to the effect of the ion and the time period of implantation. The bottom and sides behave as optical sinks, rather than as reflection or scattering centers.

Application of ion implantation to LiNbO.sub.3 integrated, optical

A surface acoustical wave (SAW) waveguide device which compensates for dispersion by utilizing diffused substrates. Various embodiments have in-diffused or out-diffused core regions in which the ray is channeled that are topped by a thin metallic film overlay. Partially surrounding each core region are cladding portions which are also selectively in-diffused or out-diffused and may be covered by the metal overlay. By varying the amounts of in-diffusion or out-diffusion for the particular application, the effects of dispersion are minimized.

Growing community of inventors

Springfield, VA, United States of America

Thomas G Giallorenzi