Abstract: A seismic sensor contains a geophone (4) disposed within a housing (12). The sensor is also provided with locking means (14, 19, 21) that can either lock the geophone 4 relative to the housing, or can allow the geophone to rotate within the housing. The geophone (4) is enclosed in a casing (1) which is so constructed that the overall mass distribution of the casing and geophone is uneven. The casing and geophone assembly thus adopts a preferred orientation when the sensor is unlocked. A liquid can be disposed within the housing, so that the casing (1) and geophone (4) can float when the sensor is unlocked.

Abstract: A seismic vibrator system for imparting compressional and shear wave vibrations into the earth has an earth contacting base with a vertical post. A tubular hub is slidably received on the post in a piston/cylinder relationship. Spaced apart horizontal top and bottom plates are secured to the hub. A mass is slidably supported between the plates. Pistons interconnect the hub and the mass. Hydraulic energy is used to reciprocate the mass vertically on the post and horizontally between the plates.

Abstract: An acoustic sensor for measuring acoustic waves contained in fluid flow flowing over the sensor. The acoustic sensor reduces any unwanted self-noise associated with the flowing fluid by providing a nose cone having proper aerodynamic properties and by positioning the diaphragm of a microphone of the sensor at a location where any unwanted noise is at a relatively low level. The nose cone has a rounded, blunt or even sharp tip neither of which creates any major disturbances in the flowing fluid which it intercepts.

Abstract: An ultrasonic waveguide includes a fluid-tight thin-walled tube filled with a viscous, compressible fluid. One end of the tube is coupled to a transducer for transforming electrical energy into waves of ultrasonic energy which propagate the length of the tube. The other end of the tube has a window or refracting "shoe" for transmitting or refracting the propagating ultrasonic wave therethrough. The tube has a substantially constant cross section, preferably circular. The internal diameter of the preferred circular tube is in the millimeter regime, preferably from 0.25 to 1 mm. The wall material is preferably metal, plastic or metal/plastic composite.

Abstract: A laminate acoustic window for sonar systems having a pair of septa sandwiching a core therebetween, the core being made of a low shear high elongation to break material, the septa being formed of a relatively low density, high modulus material. The windows of the invention are characterizied by unusual freedom from attenuation loss over a wide frequency range. The windows are further substantially self damping and avoid thereby a generation of significant quantities of deleterious noise due to self generated vibration and transmitted vibration.

Abstract: A tank level meter includes an elongated sound conductor of a solid material extending over the entire height of the tank. A sound generator is coupled to one end of the sound conductor to excite thereon surface waves and the opposite end of the conductor is coupled to a sound receiver. Due to different acoustic impedances of the material of the sound conductor of the fluids present in the tank that means of the air and of the liquid whose level is to be measured, the sound waves propagating at the interface of the sound conducting member and fluids arrive to the receiver with a phase shift which is proportional to the liquid level in the tank. By a suitable selection of materials of the sound conductor it is possible to obtain an unambiguous measuring signal at the receiver or a measuring signal having a high resolution. By using at least two sound conductors in the tank it is possible to obtain both a single value volume reading and a high resolution.

Abstract: A tank level meter includes an elongated sound conductor of a solid material extending over the entire height of the tank and having a coating partially surrounding it. A sound generator is coupled to one end of the sound conductor to excite thereon surface waves and the opposite end of the conductor is coupled to a sound receiver. Due to different acoustic impedances of the material of the sound conductor of the fluids present in the tank that means of the air and of a liquid whose level is to be measured, the sound waves propagating at the interface of the sound conducting member and fluids arrive to the receiver with a phase shift which is proportional to the liquid level in the tank. By a suitable selection of materials of the sound conductor and coating it is possible to obtain an unambiguous measuring signal at the receiver or a measuring signal having a high resolution. By using at least two sound conductors in the tank it is possible to obtain both a single value volume reading and a high resolution.

Abstract: The process consists in generating a primary tube wave, in using a reflecting element for the tube wave and in recording the times of emission of the induced waves radiated by the reflecting element, in receiving and recording at least part of the induced waves, then in processing the recorded signals so as to determine the characteristics of the medium to be explored. Application in particular to exploration between boreholes.

Abstract: A housing for an acoustic logging tool apparatus for use in a well bore is disclosed. The logging tool comprises an acoustic transmitter and one or more acoustic receivers located a fixed distance from the transmitter and an elongated tubular housing having a transmitter area, an intermediate area and a receiving area. The tubular housing has a plurality of interruptions or holes in the longitudinal continuity of its wall to delay the acoustic energy passing from the transmitter to the receiver along the housing. The receiving area of the housing further having means for reducing secondary acoustic noise produced by acoustic scattering between the intermediate area and the receiving area.

Abstract: A coupler for use between an ultrasonic transducer probe and a sample to be examined thereby to keep the ultrasonic transducer probe and the sample spaced a prescribed distance from each other includes an acoustic lens in an area through which a ultrasonic signal is to pass from the ultrasonic transducer probe. The acoustic lens allows the focusing point of the lens of the ultrasonic transducer probe to be shifted to a desired position. Since the ultrasonic transducer probe and the sample are spaced from each other by the coupler, the image of an observed region of the sample can be positioned in a wide field of view on a screen.

Abstract: An airgun impulsive energy source has an elongated shaft bearing surrounding the shaft of the reciprocatable shuttle for guiding the shuttle and preventing its operating or firing pistons from contacting their respective cylinder walls. The illustrative embodiment of this airgun is proportioned to be self-firing with a fast repitition rate. This airgun has an elongated cylindrical housing with discharge ports in a cylindrical wall positioned between the operating and firing chambers. The shuttle-guiding shaft bearing is positioned in the cylindrical housing between the ports and an operating chamber. This shaft-guiding bearing has a length which is more than 1.

Abstract: A single transducer ultrasonic distance sensor is disclosed which provides for range sensing down to zero distance from the sensor housing envelope with an electroacoustic transducer subject to unavoidable ringing following emission of a burst of acoustic energy. The housing is configured and the transducer mounted therein so that an acoustic path at least half as great as the distance travelled by an acoustic signal during the transducer ringing interval is provided within the housing envelope.

Abstract: An ultrasonic wave transmitter and receiver adapted to be mounted on the rear portion of a vehicle to detect the distance between the rear end of the vehicle and any obstruction located at the rear side of the vehicle. The ultrasonic wave transmitter and receiver includes an ultrasonic transducer attached to a lower part of the vehicle at a portion spaced from the rear end of the vehicle in the forward direction of the vehicle by a predetermined distance, a horn opening rearwardly from the vehicle and a wave guide tube through which the horn and the ultrasonic transducer are coupled to each other. The distance between the ultrasonic transducer and the rear end of the vehicle is selected to correspond to a time length which is long enough to sufficiently attenuate the residual oscillation of the ultrasonic transducer.

Abstract: An ultrasonic transducer which is suited to be placed in the place exposed to water, comprises an ultrasonic vibrator which transmits and receives ultrasonic wave, a horn which imparts directivity to the ultrasonic wave and a bent wave guide which connects the ultrasonic vibrator and the horn, and a reflecting plate which is provided in the bent portion of the wave guide for guiding the ultrasonic wave into the horn or the ultrasonic vibrator. According to the ultrasonic transducer of the present invention, the ultrasonic vibrator can be positioned above the horn when the horn is horizontally disposed. Therefore, the ultrasonic vibrator is not splashed with water entering from the horn.

Abstract: The level of mud in the mud return line of a rotary drilling rig is determined by cutting a hole in the top of the line and securing over the hole the saddle shaped base flange of a heat insulated sound tube supporting the ultra sonic transducer of an air coupled sonar distance measuring apparatus. The apparatus continuously digitally displays the average mud level. Upon a first manual command the apparatus makes a printed record of the level, time, and date.The apparatus give an alarm signal whenever the time averaged level departs a predetermined amount from a previously set datum level. When a second manual command is exercised the alarm is discontinued and a record of level is made and the datum level is reset to the existing level. The departure measuring means is reactivated to give an alarm signal upon sufficient departure of mud level from the new datum level.A third manual command makes a record and turns off the recorder while a trip is being made and until the third command controller is reset.

Abstract: A method and apparatus for transmission of ultrasound to and reception of ultrasound from a fluid from outside its container. An ultrasonic transducer generates sound waves longitudinally in a transmission bar that has a reflecting surface at such an angle with the ultrasonic path that the longitudinal waves are internally reflected as shear waves in the direction of an interface between the transmission bar and the fluid. The impinging of the shear-mode waves on the interface results in an efficient transmission of energy into the fluid and an efficient reception of echo signals from the fluid. Since longitudinal waves are coupled from the transducer to the metal, a rigid bond between transducer and metal is unnecessary. The coupling may be achieved by means of a liquid-filled interface that does not subject the delicate transducer to damage from stresses produced by differential thermal expansions.

Abstract: An acoustic echo-sounder arranged to determine the level of a substance in a container. The echo-sounder includes an acoustic transducer fitted to one end of an acoustic wave-guide, the acoustic impedance of which is progressively matched to the acoustic impedance of the space containing the substance in order to avoid disturbing reflections. In a preferred embodiment, the end portion of the acoustic wave-guide is constructed so that its solid cross-section diminishes progressively towards the end of the wave-guide.

Abstract: A transmitter of acoustic energy which propagates that energy in a directional manner is described. An acoustic signal generator is connected at one end of an acoustic transmission line which exhibits a certain characteristic impedance. The line has a number of ports spaced along its length. Surrounding each port is a coupler section which is antiresonant at the driven frequency and which presents a high acoustic driving point impedance to its associated port. In one embodiment, the interior diameter of the line is changed following each port as to make the acoustic pressure along the line and at each port constant, and the acoustic energy radiated in each coupler equal. Accordingly, acoustic energy is partitioned evenly at each port so as to define an array of equal strength radiators having directional acoustic signal propagating characteristics.