Abstract: Test apparatus (10) performs non-destructive testing of an object (O) to determine if it has flaws or defects. An ultrasonic wave (W) is generated and directed at the object. A return wave (R) reflected by the object is received and analyzed to determine if a flaw or defect. The return wave is converted to digital data which is stored for purposes of later analysis. For this purpose, digital signals containing the data are routed over a quiet bus (24). Digital signals are routed over the bus prior to generation of an ultrasonic wave to establish test parameters. Digital noise may occur during the transmission. A controller (22) controls routing of digital signals over the bus. The controller inhibits the flow of digital signals over the bus during that portion of an operational cycle of the apparatus during which the ultrasonic waves are produced and return waves evaluated. The controller allows transmission of digital signals over the bus at other times.

Abstract: This invention relates to an ultrasonic angle test probe comprising at least two ultrasonic transducers for respectively generating and receiving ultrasonic waves propagating in different directions. According to the invention, in order to obtain relatively small wedge shaped coupling members and small coupling surfaces on the side of the probe contacting the workpiece, a plurality of transducers are disposed above one another instead of side by side. In a typical embodiment, a first transducer is disposed on a first wedge-shaped coupling member and second transducer is disposed on a second wedge-shaped coupling member superposed upon said first coupling member for providing different angles of propagation of sound waves responsive to energizing one or the other transducer.

Abstract: This invention discloses a method and apparatus for determining the hardness of a solid workpiece. An elongated rod is excited to be mechanically resonant along its longitudinal axis and is provided at its front end with a defined contact surface of hard material (Vickers diamond). When the rod is rendered resonant at its natural frequency of vibration .omega.o, the contact surface of the rod is pressed into the surface of the workpiece, whose hardness is to be determined, under a predetermined engagement force while the rod is forcibly maintained oscillating at the frequency .omega.o. A sensor coupled to the rod provides a signal indicative of the amplitude of vibrations of the rod when in forced contact with the workpiece and such signal is fed to a computing device for providing a value indicative of the hardness of the workpiece.

Abstract: An apparatus for sensing the acoustic energy responsive deformation of a workpiece surface by optical means, that is without physical contact with the workpiece surface, comprises the use of a laser light beam illuminating the workpiece surface portion along which the acoustic energy responsive deformation is manifest. The laser light incident upon the workpiece surface is reflected at the workpiece surface and, modulated responsive to the surface deflection, is transmitted to an optical phase interferometer and to a photoelectric means associated therewith. The output from the photoelectric means is transmitted to an evaluation unit. The improvement shown in this invention concerns means for maintaining the reflected light intensity at a predetermined level by comparing the reflected light intensity with a preset level and feeding a control signal to a light control means controlling the laser light intensity incident upon the workpiece surface.

Abstract: The results of the non-destructive testing of objects with a beam of ultrasonic energy is enhanced by generating display control signals commensurate with a precisely defined region in the test object. These region related signals may be displayed as a "gate" bar on the screen of a cathode ray tube simultaneously with the display of echo related signals. Echo related signals having a magnitude greater than a threshold level, as also defined by the "gate" bar, are detected and may be employed to energize an alarm.

Abstract: A method and apparatus for determining by the pulse-echo method the acoustic velocity of a workpiece of known thickness utilize measurement of the transit time of the first rear wall echo signal and that of the second rear wall echo signal. The two transit times are then processed in a microprocessor which also controls the entire measuring cycle. For accurate measurement the transit time is defined as the time interval from the leading edge of the trigger pulse, which triggers the transmit pulse generator, to the time at which the respective echo signal exceeds a preset threshold amplitude.

Abstract: An acoustic lens having nonuniform cross sectional thickness is disposed in the path of an ultrasonic energy search beam traveling from a transducer probe to an object to be examined. In an alternative embodiment the lens has at least one contoured surface. As the lens undergoes motion in a plane substantially normal to the direction of the search beam, the search beam exhibits a varying focal zone depth and beam path for providing real time ultrasonic scanning of the examined object.

Abstract: A method and apparatus are provided for converting into digital form the analog ultrasonic echo signals received as a result of cyclically transmitted ultrasonic search signals intercepting an acoustic discontinuity in a workpiece. The ultrasonic echo signals are divided into a discrete number of raster-like scan lines which are scanned electronically by a microprocessor. Digital signals are generated for each line of the raster-like scan and such signals assume either a first or second state along the scan line in accordance with the signal amplitude along that line. As successive scans are made at progressively higher amplitudes of the echo signal, the amplitude required for varying the digital signal between the states for a particular scan line is incrementally increased with each scan line. A comparator receives at a first input the echo signals and at a second input a signal from a digital-to-analog converter whose output is incrementally increased on successive scan lines by the microprocessor.

Abstract: Focussed acoustic waves are generated free of physical contact in a light absorbing workpiece by the use of laser beam means providing a coherent light beam which in a pulsed manner impinges upon the surface of the workpiece in a Fresnel zone pattern. The zoned pattern is caused in a typical example by a suitable mask interposed between the laser source and workpiece surface. The thermal effect responsive to the laser beam energy produces in the workpiece a plurality of acoustic waves having a common focal point.

Abstract: In order to stabilize the acoustic wave amplitude in a workpiece, where such acoustic wave is generated by a laser beam pulse transmitted upon the workpiece surface, laser pulses preceding the laser pulse used for acoustic evaluation are utilized to clean the workpiece surface from contamination. Cleaning of the workpiece surface to the bare metal provides a normalized surface condition in respect to absorbed pulsed laser beam energy and, hence, produces acoustic waves of substantially constant amplitude. Either the same laser producing the acoustic wave or a separate laser is used for vaporizing contamination at the workpiece surface where an acoustic wave is subsequently to be produced.

Abstract: A clock circuit comprising a synchronizable voltage controlled oscillator in combination with a programmable address means, which address means is adjusted commensurate with the acoustic velocity of the workpiece, provides clock pulses from the oscillator having a stable and accurate acoustic velocity dependent frequency. An entrant surface responsive electrical signal responsive to an ultrasonic search signal entering the workpiece is also provided to the clock circuit for assuring that the clock pulses are synchronized with the receipt of the electrical signal.

Abstract: A receiver probe for ultrasonic energy is described in which the surface deformation caused by compressive wave energy affects a thin gas-filled gap, its width being in the order of 10.sup.-7 meter. The gap is formed by opposing surfaces of an optical prism and an optical interference means. A beam of light is conducted to the boundary surface between the prism and gas. Changes in reflected and/or transmitted light beam portions resulting from compressive wave energy induced changes in gap width are sensed by opto-electric means.

Abstract: Ultrasonic waves present on the surface of a workpiece are received contact-free by an optical sensing arrangement which includes a frequency stabilized single mode laser which illuminates the vibrating surface portion. Reflected light from the illuminated portion, which light is frequency modulated by the Doppler effect of the ultrasonic wave, is collected by a lens and applied to a narrow band absorption light filter. The frequency of the laser and the filter are selected to cause the center frequency of the light to fall at a point along the steepest slope of the filter absorption curve. The change in light frequency causes a corresponding change in light intensity passing through the light filter and the filtered light, now amplitude modulated, is provided to photoelectric means. A feedback circuit maintains the frequency of the laser constant.

Abstract: For sensing the presence of an ultrasonic wave propagated within a workpiece at the surface of such workpiece, the workpiece surface is illuminated with a laser beam and opto-electric means, such as an interferometer, are used to sense the minute workpiece surface deformation caused by the ultrasonic wave front. In order to sense the ultrasonic waves which are incident upon the workpiece surface at an oblique angle, the workpiece surface is illuminated in a pattern of equidistantly spaced strips. The spacing of the strips is determined by the angle of the ultrasonic wave and the wavelength of the ultrasonic wave. The resulting electrical signals are processed simultaneously or in sequence.

Abstract: A method and apparatus for producing on the surface of a workpiece an ultrasonic pulse wave without physical contact comprise the use of a laser beam illuminating a small, striplike, portion of the workpiece surface and such portion being moved with uniform motion along a linear axis over a predetermined distance. The angle of propagation of the resulting ultrasonic wave is a function of the propagation velocity of sound in the workpiece and the velocity of the illuminated portion along the linear axis.

Abstract: In a pulse echo ultrasonic velocity measuring apparatus timing gate signals corresponding to the transit time of search signals traveling through a workpiece are generated. The quantity of fixed frequency pulses occurring during successive timing gate signals is counted and accumulated using time interval averaging techniques until a predetermined quantity of pulses commensurate with the thickness of the workpieces is accumulated. Concurrently, the quantity of search signals required to accumulate the predetermined quantity of pulses is counted. The quantity of search signals counted is commensurate with the acoustic velocity of the workpiece.

Abstract: A pulse-echo ultrasonic transducer probe includes a substantially centrally disposed axial bore running therethrough and a radial slot extending from the bore to the periphery of its housing. A slotted cap dimensioned to rotatably fit over the top of the housing is provided with a hollow semi-circular stem extending into the bore, the slot of the cap being aligned with the longitudinal opening of the stem. The slot of the cap and that of the transducer, when passing a surgical instrument through the bore into an opaque body, are rotatably adjusted so that they are out of registry with one another for supporting the surgical instrument and for maintaining the instrument in the center of an ultrasonic search beam. Subsequently, after the instrument has reached the desired position in the body the slots are brought into registry for providing removal of the transducer probe from around the instrument.

Abstract: A pulse peak detector circuit for use in measuring the peak amplitude of a fast rise time, narrow pulse width pulse as in commonly encountered in an ultrasonic non-destructive testing instrument includes two amplifying means. A first amplifying means compensates small amplitude signals for the characteristics of a unidirectional current conducting means forming a part of the detector circuit while the second amplifying means provides conventional amplification of the applied signal.

Abstract: A method and apparatus for ultrasonic nondestructive testing of workpieces include automatic compensation of echo responsive electrical signals commensurate with preprogrammed test parameters. The test parameters include at least one of the following: depth dependent correction of the individual DGS (distance, gain, size) values for each respective probe; correction for material related properties of the workpiece and coupling medium; correction for temperature affecting the testing of the workpiece. Preferably, a compensating signal generated commensurate with the sum of the correction signals is used for varying either the gain of a receiver amplifier or a predetermined level provided to a comparator circuit or both. Embodiments disclosed are applicable for processing both analog and digital echo responsive electrical signals.

Abstract: A real-time ultrasonic imaging system includes a display which is compensated for the non-ideal characteristics of the search beam profile. Echo responsive electrical signals are provided to a preprogrammed computing means for being processed to compensate for the characteristics of the test probe. The processed signals are displayed as being in focus at all distances from the probe, thereby resulting in an image exhibiting improved resolution.