US Government As Represented by the Secretary of the Army

Other

Active Signal Technologies, Inc.

Frank J Crowne

Keith Bridger

Arthur V Cooke

John M Sewell

Joseph J Lutian

Steven C Tidrow

Donald E Wortman

Richard P Leavitt

Daniel M Potrepka

Clyde A Morrison

Philip M Kuhn

George L Small

Edward J Passaro

Bernard J Rod

Steve C Tidrow

A detector for electromagnetic radiation such as millimeter wave and infrared employs a ring-shaped ferroelectric element having a temperature affected by an absorber for the radiation. The dielectric constant of the ferroelectric material is a strong function of the temperature near its Curie temperature. The resonant frequency of the ferroelectric element is detected by applying a swept-frequency signal to the circuit and detecting the frequency which enhances the energy of the pulse. A two-dimensional camera for the radiation employs a two-dimensional array of these ferroelectric resonant circuits and a system for rapidly interrogating their resonant frequencies on a sequential basis.

Ferroelectric radiation detector employing frequency modulated readout

A delay line is made by sandwiching a thin slice of ferroelectric between two 'cladding' layers of relatively low-&#x3b5;, low loss material to form a dielectric slab waveguide, and may support the propagation of electromagnetic guided waves and hence be used as a source of electric-field tunable time delay. There is a frequency range within which a dielectric-slab delay line behaves like a homogeneous transmission line with an 'average' dielectric constant that is much lower than that of the ferroelectric, thereby ameliorating the difficulty with the high dielectric constant of the ferroelectric material. The thin slice of ferroelectric material &#x201c;expels&#x201d; a large fraction of the wave electric field, causing most of it to occupy the low-loss cladding material, greatly reducing the propagation loss along the delay line while allowing delay time to be varied by applying an electric-field through the ferroelectric within the cladding structure.

Ferroelectric delay line based on a dielectric-slab transmission line

A compact hybrid actuator has a fluid pump ( ) arranged to supply fluid to an actuator ( ). The pump has at least one electrically-powered solid-state pump driver ( ) provided with a displacement element ( ). The position of this displacement element modulates the volume of a fluid chamber ( ). A driven valve ( ) is operatively arranged to control the flows of fluid with respect to the pump chamber, and has one member ( ) movable relative to a body ( ) to modulate the opening of ports ( ) so as to form at least one three-way valve. A valve driver ( ) is operatively arranged to operate the driven valve. Electrical power is provided to each valve and to the valve driver so as to operate these various elements in synchronism with one another. The improved pump driver and driven valve may be operated at frequencies in excess of 1 kHz.

Compact hybrid actuator

A non-invasive apparatus and method are disclosed for measuring intracranial pressure. The intracranial measurement system transmits acoustic signals through a cranium and provides an indication of intracranial pressure based on the received acoustic signals after interaction with the brain. Properties such as acoustic transmission impedance, resonant frequency, resonance characteristics, velocity of sound and the like may be measured and correlated with intracranial pressure. The acoustic signals have typical frequencies of less than 100 kHz, for example, in the audible and sub-audible frequency ranges. The intensity of the transmitted acoustic signals used to determine intracranial pressure is relatively low, resulting in little or no health risks during short term or long term monitoring.

Apparatus and method for measurement of intracranial pressure with lower

A method and apparatus for controlling a chemical reaction by heterogeneous catalysis, in which a surface acoustic wave (SAW) is propagated along a surface of a piezoelectric element in contact with liquid or gaseous substances to be chemically reacted, to thus generate an electric field at the surface of the element which initiates and sustains the desired reaction. The catalysis rate can be varied by varying the frequency and/or intensity of the surface acoustic wave. The surface of the element may be coated with a very thin film of a catalytic group 8 metal which can be penetrated by the SAW electric field. In such an embodiment, normal catalysis proceeds via chemisorption, and the SAW element field acts to increase the catalysis rate.

Method for chemical reaction control using a surface acoustic wave device

A Peierls transition far-infrared radiation source comprised of a block of an organic one dimensional metal stressed at the ends and having a potential difference applied.

Peierls-transition far-infrared source

Growing community of inventors

Laurel, MD, United States of America

Frank J Crowne