Virginia Tech Intellectual Properties Inc

Lambda Instruments, Inc.

Other

Carvel Holton

Erik Herz

Kenith Meissner

Corey Paye

Mehdi Ahmadian

Richard O Claus

Paul G Duncan

An optical method and apparatus are described for the measurement of properties of a travel vehicle or a travel surface upon which the travel vehicle travels, which includes providing an incident light from a light source to the travel surface, collecting light reflected from the travel surface, determining a surface induced Doppler shift from the incident and collected light and determining at least one of a motion property of the travel vehicle and a surface property of the travel surface based on the determined surface induced Doppler shift.

Doppler sensor for the derivation of torsional slip, friction and related parameters

Holey optical fibers (e.g. photonic fibers, random-hole fibers) are fabricated with quantum dots disposed in the holes. The quantum dots can provide light amplification and sensing functions, for example. When used for sensing, the dots will experience altered optical properties (e.g. altered fluorescence or absorption wavelength) in response to certain chemicals, biological elements, radiation, high energy particles, electrical or magnetic fields, or thermal/mechanical deformations. Since the dots are disposed in the holes, the dots interact with the evanescent field of core-confined light. Quantum dots can be damaged by high heat, and so typically cannot be embedded within conventional silica optical fibers. In the present invention, dots can be carried into the holes by a solvent at room temperature. The present invention also includes solid glass fibers made of low melting point materials (e.g. phosphate glass, lead oxide glass) with embedded quantum dots.

Optical fiber with quantum dots

The disclosed invention concept utilizes a homodyne/heterodyne interferometer technique in a modified lidar in such a manner as to sense the rotational velocity magnitude and sense of a rotating (or &ldquo;spinning&rdquo;) object. Sensing is accomplished in assessing either the Doppler bandwidth of a single axis system or in sensing the frequency separation of Doppler spectrums in a &ldquo;two&rdquo; axis system. The technique is unique in that the Doppler bandwidth is linearly proportional to rotational velocity and independent of intercept position in the rotation plane. The technique as disclosed is based on optical fiber lidar techniques, but can be implemented in free-space optics as well. The disclosed invention therefore comprises both a technique for utilization of an optical fiber lidar and a new arrangement of lidar elements. Compact and cost effective, standoff rotation velocity sensors and systems can be fabricated with this technique.

Doppler rotational velocity sensor

A method of generating in-quadrature signals is disclosed. The method comprises phase shifting a Doppler frequency-shifted signal; phase shifting a local oscillator signal; mixing the phase shifted Doppler frequency-shifted signal and the phase-shifted local oscillator signal generating thereby a signal which includes the phase-shifted Doppler frequency-shifted signal and a further phase-shifted local oscillator signal; and mixing the unphase-shifted Doppler frequency-shifted signal and the unphase-shifted local oscillator signal generating thereby a signal which includes the unphase-shifted local oscillator signal and a further phase-shifted Doppler frequency-shifted signal. A method of determining the velocity of an object is also disclosed. The method comprises receiving a Doppler frequency-shifted signal reflected or backscattered from the object; generating a local oscillator signal; based upon the received Doppler frequency-shifted signal and the local oscillator signal, generating an in-phase signal; based upon the received Doppler frequency-shifted signal and the local oscillator signal generating an in-quadrature signal; summing the in-phase signal and the in-quadrature signal; and transforming the summation of the in-phase signal and the in-quadrature signal. A lidar is disclosed comprising an optical system for transmitting an output signal to an object and receiving thereby a Doppler frequency-shifted signal reflected or backscattered from the object; a signal mixing assembly receptive of the Doppler frequency-shifted signal and a local oscillator signal generating thereby an in-phase signal and an in-quadrature signal; and a signal transformer for transforming the in-phase signal and an in-quadrature signals. A signal mixing system is disclosed comprising an array of signal couplers receptive of a Doppler frequency-shifted signal and a local oscillator signal generating thereby an in-phase signal which includes the unphase-shifted local oscillator signal and a phase-shifted Doppler frequency-shifted signal and an in-quadrature signal which includes the phase-shifted Doppler frequency-shifted signal and a further phase-shifted local oscillator signal; and a plurality of signal detectors receptive of the in-phase and in-quadrature signals.

Quadrature processed LIDAR system

Described are the design of a rare earth iron garnet sensor element, optical methods of interrogating the sensor element, methods of coupling the optical sensor element to a waveguide, and an optical and electrical processing system for monitoring the polarization rotation of a linearly polarized wavefront undergoing external modulation due to magnetic field or electrical current fluctuation. The sensor element uses the Faraday effect, an intrinsic property of certain rare-earth iron garnet materials, to rotate the polarization state of light in the presence of a magnetic field. The sensor element may be coated with a thin-film mirror to effectively double the optical path length, providing twice the sensitivity for a given field strength or temperature change. A semiconductor sensor system using a rare earth iron garnet sensor element is described.

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Blacksburg, VA, United States of America

Carvel Holton