USA As Represented by Secretary of the Navy

Brandon Cochenour

Linda Mullen

Alan Edward Laux

Amanda Alley

Robert M Lee

Lila Rodgers

Justin Nash

Derek Alley

A method and system for optical vortex transmissometry. The method uses optical orbital angular momentum (OAM) and optical vortices to discriminate coherent non-scattered light from incoherent scattered light. The system includes a laser which transmits a Gaussian laser beam through a medium. An OAM generating device is placed before a photodetector receiver. Coherent, non-scattered light passing through the OAM generating device forms an optical vortex, used to discriminate against the unwanted scattered signal that does not form a vortex. Alternatively, the system includes a transmitter, which generates one or more OAM modes, which are transmitted through a turbid medium. At the receiver, an OAM detection device analyzes the OAM mode spectrum of the received light. Coherent non-scattered light retains the OAM encoded at the transmitter, while scattered light does not. The attenuation of the channel is determined by comparison of the received OAM mode spectrum relative to the transmitted OAM mode spectrum.

Optical vortex transmissometer

A method and system for optical vortex transmissometry. The method uses optical orbital angular momentum (OAM) and optical vortices to discriminate coherent non-scattered light from incoherent scattered light. The system includes a laser which transmits a Gaussian laser beam through a medium. An OAM generating device is placed before a photodetector receiver. Coherent, non-scattered light passing through the OAM generating device forms an optical vortex, used to discriminate against the unwanted scattered signal that doesn't form a vortex. Alternatively, the system includes a transmitter which generates one or more OAM modes which are transmitted through a turbid medium. At the receiver, an OAM detection device analyzes the OAM mode spectrum of the received light. Coherent non-scattered light retains the OAM encoded at the transmitter, while scattered light does not. The attenuation of the channel is determined by comparison of the received OAM mode spectrum relative to the transmitted OAM mode spectrum.

A method and system for imaging in degraded visual environments. The system includes a laser that is positioned to transmit a Gaussian beam toward a target object located within the degraded visual environment. An optical receiver is positioned to receive return signals. A helical phase element is positioned between the target object and the optical receiver. The return signals pass through the helical phase element. The helical phase element separates coherent and incoherent light by imparting orbital angular momentum on the coherent returns to form an optical vortex.

Optical detection of an object in a turbid medium using an optical vortex

An optical imaging system and method for use in a degraded visual environment is provided. A wideband modulated laser pulse is transmitted from a first location through a medium toward a target object. An input of the transmitted wideband modulated laser pulse is detected by an optical receiver. A target modulated laser pulse, reflected from the target object is detected by the optical receiver. The transmitted and reflected laser pulses are filtered by a bandpass filter, based on a predetermined modulated frequency range. The filtered transmitted and reflected laser pulses are digitized by an analog-digital converter. The digitized transmitted laser pulse is correlated with digitized reflected laser pulse by a digital matched filter, wherein the matched filter produces a passband matched filter output. A range of the target object is determined based on the matched filter output.

Digital passband processing of wideband modulated optical signals for enhanced imaging

The present invention is directed to an apparatus and method for bistatic laser range imaging. The apparatus utilizes two light sources, two receivers, a demodulator and an image processor such that a three dimensional image is produced. The method includes generating beams of intensity modulated light, one toward a target, another toward a receiver. The light toward the target reflects from the target toward another receiver. The modulation envelopes of the beams of light are demodulated into components, the components digitized, then decimated, and a three dimensional image is constructed from the digitized components.

Method and apparatus for bistatic laser range imaging

An image enhancer that includes a laser for emitting an optical signal toward an object in a turbid medium, a modulator for modulating laser intensity of the optical signal, an RF source for driving the modulator and for providing a reference signal, an optical detector for detecting the modulated optical signal that is reflected from the object, the optical detector converting the reflected optical signal into an electrical signal, the electrical signal having RF and DC components, an I/Q demodulator for mixing the RF component of the electrical signal with the reference signal and producing in-phase and quadrature phase signal components that can be digitized and processed such that both contrast and range images of the object are produced.

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Alexandria, VA, United States of America

Brandon Cochenour