4,162,476 43.30. Yj ACCELERATION BALANCED HYDROPHONE II

Bryce L. Fanning, assignor to Her Majesty the Queen in the right of Canada

24 July 1979 (Class 340/10); filed in Canada 18 February ß 1976

The pressure sensitive element of this hydrophone is a piezo- electric ceramic cylinder 1. Inside it is a second cylinder 7 which is loaded by a mass 8. This inner cylinder is isolated from acoustic pressure by the outer one and by the end cap 3, but it responds to

4.

5 2 15

I

vertical acceleration which the supporting cable may introduce. By connecting the two elements in opposition, with appropriate weight- ing, the response of the hydrophone to vertical acceleration is can- celed out. Moreover, circuitry may be included to cancel the re- sponse to the oscillating hydrostatic pressure that results from ver- tical motion of the hydrophone.-LB

4,163,382 43.35.Sx METHOD AND APPARATUS FOR

OPTOACOUSTIC SPECTROSCOPY

Nabil M. Amer, assignor to the United States of America 7 August 1979 (Class 73/24); filed 28 April 1978

A method of laser optoacoustic spectroscopy is described which is said to be more sensitive and flexible that• prior techniques in op- toacoustic spectroscopy. A laser beam is introduced into an absorp- tion cell through a continuously variable mechanical chopper. A microphone inside the cell measures acoustic coupli, ng from the pulsed optical radiation. Acoustic signals in the cell are observable when the laser radiation frequency corresponds to an absorption band of the gas. Signal e .nhancement occurs when the chopper fre- quency corresponds to an acoustically resonant mode of the cell. The invention is concerned with doping optically nonabsorbing ma- terials (gases, liquids, solids, aerosols) with a relatively small amount of an optically absorbing gas, such that the total mixture is opto- acoustically active. By this method, the velocity of sound, the ratio of specific heats, the heat conductivity, the viscosity, and/or the molecular weight of the nonabsorbing material may be inferred through measurements of the cell resonant frequencies and ampli- tudes.-JVB

4,164,717 43.35.Sx ACOUSTOOPTIC MODULATION AND DEFLECTION

Richard N. Blazey, assignor •o Eastman Kodak Company 14 August 1979 (Class 332/721); filed 7 November 1977

Acoustoopfic apparatus is described for intensity modulating and angularly deflecting a beam of coherent light. In this apparatus, the need for optics between the modulator and deflector has been eliminated, thereby reducing light loss, size, and cost.-JVB

4,166,270 43.30.Yj TESTING OF SEISMIC STREAMERS

Auseklis Brastins and Ralph I• Stenger, Jr., assignors to Gulf Research & Development Company

28 August 1979 (Class 340/5 C); filed 26 January 1978

A typical hydrophone streamer for seismic prospecting includes 48 to 96 groups of hydrophones, each in an oil-filled section of flex- •le tubing which may be 250 ft long. Short sleeves of tubing, called boots, connect the sections end to end. In each section, some 32 piezoelectric hydrophones are connected in parallel to a match- ing transformer and constitute one channel of the streamer. Electri- cal leakage across the hydrophones, possibly from the intrusion of salt water, m be serious because the hydrophone response down to 8 Hz is important. This invention provides circuits in each boot for testing the adjacent channel. A common dc voltage controls.all the test circuits simultaneously, while the responses of the channels are recorded individually aboard the ship that tows the streamer. With one polarity of the control voltage, a step function voltage is intro- duced in series with each transformer primary. With the opposite polarity, an ac test signal is introduced by a relaxation oscillator whose frequency is a function of the insulation resistance. Only electrical tests are contemplated for this system. Acoustical tests are not considered.-LB

4,150,637 43.35.Yb ULTRASONIC DEVICE FOR SCARING

ANIMALS FROM A MOVING VEHICLE

Monroe Penick, Sherman, Illinois 62684 24 April' 1979 (Class !16/58 R); filed 7 November 1977

This patent describes the use of an ultrasonic "dogwhistle" mounted in front of a vehicle, with schematic illustrations of air scoops for securing adequate air flow to energate the whistle. No account is made for inertia of reaction by animals who may be luckless enough to hear the alarm when directly in front of the moving vehicle.-RWC

4,151,834 43.35. Yb ULTRASONIC DIAGNOSTI• APPARATUS

Shigeru Sato, Michiyoshi Uranishi, assignors to Tokyo Shibaura Electric Company,

1 May 1979 (Class 128/660); filed 15 July 1977

This patent describes with considerable detail a system for ultra- sonic exploration of a body comprising a mechanically swept, ultra- sonic transducer adapted to scan a portion of the body, and elaborate

741 J. Acoust. Soc. Am. 67(2), Feb. 1980; 0001-4966/80/020741-02-$00.80; ¸ 1980 Acoust. Soc. Am.; Patent Reviews 741

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