Princeton University

The Ohio State University

Other

The Boeing Company

Metrolaser, Inc.

Plasma Tec, Inc.

Richard B Miles

Arthur Dogariu

Mikhail Shneider

James B Michael

Walter Reuben Lempert

Joseph William Rich

Walter R Lempert

Sergy O Macheret

Charles E Albright

Joseph Steven Silkey

Alexander Goltsov

Jacob George

Sergey O Macheret

Noah Finkelstein

Alexandre Likhanskii

Zhili Zhang

Andrey Y Starikovskiy

Matthew R Edwards

Described herein are systems and methods for ensuring plasma homogeneity in a discharge cell. The discharge cell may include a first hollow electrode and a second hollow electrode spaced away from the first electrode to define a discharge gap therebetween. A fluid inlet port may in fluid communication with an internal bore of the first electrode. A fluid outlet port may be in fluid communication with the discharge gap. A first pair of viewports may define a first optic pathway through the discharge gap. A second pair of viewports may define a second optic pathway through the discharge gap. A third pair of viewports may define a third optic pathway through the discharge gap, the third optic pathway defined through the hollow interior of the first and second electrodes.

Discharge cell systems and methods

Disclosed is a process and device that enables ultra-high resolution one- and two-dimensional spatial imaging of Rayleigh, Raman and Thomson spectral features without the need for a spectrometer. The disclosed approach provides the capability for imaging of a single spectral feature such as a single rotational Raman line and the simultaneous elimination of background scattering, or for separating the rotational Raman image from the Rayleigh scattering. High collection efficiency provides the opportunity for single pulse time frozen images to be acquired.

Slow light imaging spectroscopy

An apparatus for the imaging of gaseous fluid motion is disclosed. The apparatus includes a sub-nanosecond pulsed laser. The sub-nanosecond pulsed laser is configured to cause a particle species to fragment and for the recombining fragments subsequently to fluoresce. The apparatus also includes a gaseous fluid comprised of particle species. The apparatus also includes a time gated camera. The time gated camera configured to capture at least one image of the fluorescence from the recombining particle fragment species displaced after a specific time lapse following the laser pulse. Additionally, a fluid velocity can be calculated from a comparison of the image of the displaced particle species to an initial reference position and the time lapse. A Femtosecond Laser Electronic Excitation Tagging (FLEET) method of using the disclosed apparatus is also disclosed.

Femtosecond laser excitation tagging anemometry

Systems and methods for lasing molecular gases, and systems and methods of detecting molecular species are provided. The systems and methods can include the use of an excitation laser tuned to a wavelength associated with oxygen or nitrogen. The lasing can occur in both the forward and reverse directions relative to the excitation laser beam. Reverse lasing can provide a laser beam that propagates back toward the excitation laser source, and can provide a method for remote sampling of molecular species contained in the air. For example, systems and methods of detecting a molecular species of interest can be achieved by using the properties of the backward or forward propagating air laser to indicate a change in a pulse from the source of laser pulses caused by a modulation laser tuned to interact with the molecular species of interest.

Systems and methods for lasing from a molecular gas

Systems and methods for controlling flow with electrical pulses are disclosed. An aircraft system in accordance with one embodiment includes an aerodynamic body having a flow surface exposed to an adjacent air stream, and a flow control assembly that includes a first electrode positioned at least proximate to the flow surface and a second electrode positioned proximate to and spaced apart from the first electrode. A dielectric material can be positioned between the first and second electrodes, and a controller can be coupled to at least one of the electrodes, with the controller programmed with instructions to direct air-ionizing pulses to the electrode, and provide a generally steady-state signal to the electrode during intervals between the pulses.

Systems and methods for controlling flows with electrical pulses

A method and apparatus for remotely monitoring properties of gases and plasmas, and surface and sub-surface properties of materials, is disclosed. A laser beam is focused at a desired region within a gas, plasma, or material (e.g., solid or liquid) to be analyzed, generating an ionized sample region or a localized, enhanced free carrier region. A beam of microwave radiation is directed toward the ionized sample region or the free carrier region, and the microwave radiation is scattered. The scattered microwave radiation is received by a microwave receiver, and is processed by a microwave detection system to determine properties of the gas, plasma, or material, including surface and sub-surface properties.

Method and apparatus for detecting surface and subsurface properties of materials

A method and apparatus for remotely monitoring properties of gases and plasmas is disclosed. A laser beam is focused at a desired region within a gas or plasma to be analyzed, generating an ionized sample region in the gas or plasma. A beam of microwave radiation is directed toward the ionized sample region, and a portion of the microwave radiation is scattered by the ionized sample region and Doppler-shifted in frequency. The scattered, frequency-shifted microwave radiation is received by a microwave receiver, and is processed by a microwave detection system to determine properties of the gas or plasma, including velocities, temperatures, concentrations of molecular species, and other properties of the gas or plasma.

Method and apparatus for remotely monitoring properties of gases and plasmas

A method and associated apparatus for initiating and guiding an electrical discharge arc. This method preferably comprises the steps of: providing a laser beam through a predetermined gas comprising molecules amenable to vibrational excitation by a laser beam so as to cause vibrational excitation of the molecules and to define a beam path in a direction of desired electrical discharge; and propagating an electrical discharge arc so as to intersect the beam path, whereby the electrical discharge arc is directed along the beam path.

Method and apparatus for initiating, directing and constricting electrical discharge arcs

A method and apparatus for collecting and analyzing Raman scattered light includes an atomic vapor cell (,) configured to spectrally disperse light by resonant dispersion while simultaneously suppressing Rayleigh scattering and other background scattering through resonant absorption. A light source (,) is used to illuminate a sample (,). The light source (,) is tuned in the vicinity of the absorption feature of some atomic vapor. The resonant dispersion of the vapor is well known to strongly vary in the vicinity of such an absorption feature. If the light source (,) is tuned in the vicinity of the absorption, then the Rayleigh light is strongly attenuated. The Raman light is transmitted through the filter. If the filter is constructed so that the dispersive nature of the atomic vapor in the vicinity of the absorption line bends the light rays as they pass through the atomic vapor cell (,), then the Raman light can be spatially displaced.

Dispersive atomic vapor raman filter

First and second relatively high power laser beams are directed into a volume enclosing a flow field of molecules of a molecular species. The beams are focussed to form an overlapping region of the beams in the flow field, for tagging a portion of the associated molecules by driving them into their first vibrational state by stimulated Raman pumping. A high intensity beam of light is directed into the flow field proximate the overlap region for intercepting the tagged molecules, and causing them to fluoresce, thereby permitting their displacement to be measured through observation thereof, for determining the velocity of the associated molecules and flow field.

Velocity measurement by the vibrational tagging of diatomic molecules

Velocity is measured by observing velocity-related frequency shifts in light scattered from moving air molecules or particles suspended in moving air, by passing the scattered light through an absorption line filter window gas cell with a notch type attenuation profile as a function of frequency. The scattering region is illuminated with a narrow linewidth light source coincident in frequency with a strong absorption line of an absorption line filter, whereby light scattered from stationary air molecules or particles is passed into the filter and a portion of that light falling within the strongly attenuated region is absorbed. As the velocity of the molecules or particles in the scattering region increases, the scattering frequency is shifted due to the Doppler effect, and the portion of the scattered light falling beyond the filter cutoff increases, causing the intensity of the light transmitted through the filter increase. The intensity of the transmitted light is directly related to the shifted frequency, thereby providing a measurement of the velocity of the gas. The cell transmission can be quantified by comparing the intensity of the light transmitted through the cell with the intensity seen in the absence of the cell, thereby leading to a quantitative measure of the relative velocity between the light source and scattering volume.

Absorption line filter window and method for velocity measurements by

A laser beacon mounted on a first aircraft emits a beam which is sensed by an optical detector on a second aircraft in such a manner that a collision proximity warning device is triggered and/or collision avoidance maneuvers are initiated. The system is intended to prevent aircraft collisions which occur under visual flight regulation (VFR) conditions and which constitute in excess of 90% of civil aircraft mid-air accidents. In the preferred embodiment a horizontally collimated, vertically diverging laser beam is made to rotate 360.degree. in polarization while simultaneously rotating 360.degree. in azimuth with respect to the first aircraft. The optical detector mounted on the second aircraft preferably comprises a pair of horizontally offset light collectors which include narrow spectral width filters respectively and various other components which collectively determine the bearing, range and relative heading of the first aircraft. The information is stored so that subsequent signals arising from the first aircraft may be compared to determine trajectories and range rates. Collision warning and/or collision avoidance actions may then be started if the information indicates a high probability of collision. Alternative embodiments of the optical detector apparatus can be constructed with varying complexities to meet the needs of aircraft operating at different speeds or in different flight environments.

Growing community of inventors

Princeton, NJ, United States of America

Richard B Miles