Jacques R Chamuel

US Patent:

44818211, Nov 13, 1984

Filed:

Aug 8, 1983

Appl. No.:

6/521114

Inventors:

Jacques R. Chamuel - Framingham MA

Assignee:

The Charles Stark Draper Laboratory, Inc. - Cambridge MA

International Classification:

G01N 2904

US Classification:

73617

Abstract:

A contactless self-scanning electro-elastic nondestructive testing technique is described for determining in real time the presence, location, number and size of defects present on the surface of a material under test. In one embodiment the apparatus includes means for inducing eddy currents or current flow in the surface of the conductive material. A magnetostrictive delay line is disposed parallel to the direction of current flow and equidistant and in fixed spatial relation with the surface. The presence of a crack or defect in the surface proximate to the delay line creates transverse eddy currents or transverse currents in the material which interact locally with the magnetostrictive delay line to induce elastic waves in the delay line. The elastic waves are generated in the delay line only at locations corresponding to the edges of the defects. An ultrasonic sensor coupled to the delay line is used to detect the elastic waves travelling in the delay line.

US Patent:

41211553, Oct 17, 1978

Filed:

Dec 2, 1976

Appl. No.:

5/747072

Inventors:

Jacques R. Chamuel - Allston MA

Assignee:

The Charles Stark Draper Laboratory, Inc. - Cambridge MA

International Classification:

G01R 3300

US Classification:

324207

Abstract:

A position determining system in which a delay element has at least one driver transducer at at least one position and at least one receiver transducer at at least one other position, the transducers being arranged so that a traveling wave signal at the driver transducer travels along the delay element from the first said at least one position to said at least one other position so that a distance which is to be measured is traversed more than once. Certain embodiments accomplish such operation by providing a "folded" or U-shaped delay element, the driver and receiver being located on separate legs thereof so that the traveling wave traverses both legs of the delay element so that the distance which is to be measured is traversed twice, thereby increasing the resolution of the overall device. In another embodiment, for example, a pulse is triggered a plurality of times at at least one driver transducer means so that it traverses the distance from the at least one driver transducer means to at least one receiver transducer means a plurality of times.

US Patent:

50311581, Jul 9, 1991

Filed:

Mar 23, 1984

Appl. No.:

6/592918

Inventors:

Jacques R. Chamuel - Framingham MA

Assignee:

The Charles Stark Draper Laboratory, Inc. - Cambridge MA

International Classification:

G01V 140

US Classification:

367118

Abstract:

Method and apparatus for determining the precise location of a drill bit tip relative to specified locations on a workpiece in precision automatic machining operations. Elastic waves are induced in a drill shank, guided through the shank to the drill bit tip and couple to the surrounding workpiece material in contact with the tip of the drill bit. Elastic wave sensors are disposed in elastic wave transmitting relation with the workpiece to detect the induced elastic waves. The precise location of the drill bit tip is determined by computing the propagation time of elastic waves from the drill bit tip to each of the respective sensors. In one embodiment, elastic waves are induced with contactless electromagnetic coupling via a magnetostrictive transduction technique. Other techniques for inducing elastic waves in a drill bit are described.

US Patent:

42312604, Nov 4, 1980

Filed:

Nov 3, 1978

Appl. No.:

5/957462

Inventors:

Jacques R. Chamuel - Framingham MA

Assignee:

The Charles Stark Draper Laboratory, Inc. - Cambridge MA

International Classification:

G01N 2900

US Classification:

73597

Abstract:

A positioning determining system using a delay element and driver transducer for producing a traveling wave in the delay element, the presence of a traveling wave being detectable by a receiver transducer for determining the relative positions of the driver and receiving transducers. In accordance with the invention, a driver transducer, the delay element, and a second transducer form a self-excited feedback loop oscillator, the frequency of oscillation of which is determined by the spatial filtering provided by the second transducer so as to generate a traveling wave having a selected wavelength. The system includes automatic frequency selection to compensate for position sensing errors due to changes in the velocity of propagation of elastic waves arising because of temperature effects on the delay medium.

US Patent:

45933855, Jun 3, 1986

Filed:

May 19, 1983

Appl. No.:

6/496124

Inventors:

Jacques R. Chamuel - Framingham MA

Assignee:

The Charles Stark Draper Laboratory - Cambridge MA

International Classification:

H04R 144
G01B 902

US Classification:

367149

Abstract:

An optoacoustic hydrophone for detection of acoustic waves in a fluid such as sea water. The hydrophone includes an optical waveguide comprising a fiber optic input lead, a fiber optic sensor, and a fiber optic exit lead, an optical subassembly and a signal processor. A coherent light beam generated by the optical subassembly is transmitted through the input lead and the sensor which is disposed in the fluid. Acoustic waves in the fluid modulate the index of refraction of the fiber optic sensor thereby modulating the transmitted light beam. The modulated light beam is directed through the fiber optic exit lead to a focus on one of two photodetectors. The other photodetector is oriented for receipt of light reflected from a partially reflective mirror disposed between the input fiber optic lead and the fiber optic sensor. The two light beams impinging on respective photodetector are combined with unmodulated light beams of slightly different frequencies to produce an interference pattern at each photodetector. Each photodetectors produces an electrical signal representative of the interference pattern and the respective electrical signals are applied to a phase meter.

US Patent:

47633352, Aug 9, 1988

Filed:

Nov 24, 1987

Appl. No.:

7/129376

Inventors:

Jacques R. Chamuel - Framingham MA

Assignee:

The Charles Stark Draper Laboratory, Inc. - Cambridge MA

International Classification:

H01S 3096

US Classification:

372 33

Abstract:

A laser diode assembly and associated heat sink and excitation leads constructed to avoid the electromagnetic or magnetostrictive generation of stress or elastic wave disturbances in the diode, heat sink or associated components so as to maintain spectral purity in the diode laser emission. An improved laser diode assembly avoids the generation of elastic waves or vibrations within the leads, heat sink or associated structure of a laser diode by running excitation leads in a magnetic field cancellation arrangement to prevent magnetostrictively induced elastic waves in structure connected to the laser diode and to avoid vibration induced by coupling between the lead currents and external magnetic fields. The heat sink, electrical input and return leads and associated structure may be fabricated of a nonmagnetostrictive material to avoid magnetostrictively induced acoustic disturbances created by other magnetic field sources in the use environment of the laser diodes.

US Patent:

40357627, Jul 12, 1977

Filed:

Nov 4, 1974

Appl. No.:

5/520742

Inventors:

Jacques R. Chamuel - Allston MA

Assignee:

The Charles Stark Draper Laboratory, Inc. - Cambridge MA

International Classification:

G01S 380

US Classification:

340 16R

Abstract:

Apparatus for determining linear or angular measurements or measurements of positions on a planar or curved surface, which apparatus uses at least one delay element, such as a magnetostrictive element, for example, which is capable of supporting an accoustic wave signal. The one or more delay elements may be in the form of bands, rods, wires, planar or spherical structures, and the like, and can be arranged in various embodiments to provide linear or angular position information for single, dual, and multiaxis geometry. They can be used, for example, to provide single or multispeed resolver operation and three-axis attitude read-out. In preferred embodiments the apparatus uses phase measurement techniques so that high accuracy can be achieved.

US Patent:

44611781, Jul 24, 1984

Filed:

Apr 2, 1982

Appl. No.:

6/364902

Inventors:

Jacques R. Chamuel - Framingham MA

Assignee:

The Charles Stark Draper Laboratory, Inc. - Cambridge MA

International Classification:

G08B 1902
G01N 2900

US Classification:

73599

Abstract:

A system for the detection of wing icing by monitoring variations in flexural waves transmitted through the outer plate material of an aircraft airfoil. The flexural waves in the plate of the wing airfoil are more subject to variation from the accumulation of ice on the wing than the compressional waves. The flexural waves are detected apart from the compressional waves, which tend to remain relatively constant, to provide an indication of icing. Changes in amplitude, phase or dispersion characteristics of the flexural waves are detected to indicate ice buildup, and, in one embodiment, these values are ratioed to the corresponding levels in the compressional wave in order to provide compensation for variations other than ice buildup. The ultrasonic waves may be coupled directly from a transducer to the airfoil plate or via an ultrasonic waveguide interposed between the transducer and the plate. The receiver for the ultrasonic waves to be detected may be positioned to receive direct flexural waves transmitted over a distance through the plate or flexural waves reflected from reflecting boundaries in the plate.