Abstract: An acoustic inspection device having a transducer housing opening to a face of the device to be disposed opposite a workpiece to be inspected. That face of the device having selectively located multi-piece flexible material of a selected length extending outward therefrom disposed to interface with the surface of the workpiece. A first portion of the flexible material is supplied to create, and surround, a region close to the opening of the transducer housing with a plurality of couplant supply ports around the transducer opening to form a chamber into which couplant is continuously supplied to couple the transducer to the surface of the workpiece. A second portion of the flexible material being spaced outward from, and surrounding, the first of the flexible material to create another chamber having vacuum ports in the face of the device opening into that chamber to recover couplant that leaks through the first portion of the flexible material from the couplant chamber.

Abstract: An acoustic detector which includes at least one emitter unit with a solid tapered profile spike (C) associated with an element (X) for exciting the spike so as to propagate ultrasound waves in an antisymmetrical propagation mode in the spike. The device also emits waves into a surrounding gas. At least one receive unit includes a tapered profile solid spike associated with the detector for receiving the ultrasound waves.

Abstract: An ultrasonic inspection element and method are provided for improved ultrasonic inspection of curved entry surface parts. The transducer element may be spherically focused, or have a flat surface. The transducer/mirror element combination is used to inspect through a concave or convex surface. A mirror element shapes the sound beam relative to the shape of the curved surface of the part being inspected. Curvature of the mirror is adjusted with a screw, rod, voltage modulator, or other suitable adjustment mechanism. An alternative mechanism includes multiple “quick disconnect” interchangeable curved mirror elements.

Abstract: An ultrasonic sensor includes a case member and a piezoelectric element. The case member has a hollow therein and a bottom portion provided at one end of the hollow. The bottom portion has a thick portion which extends along a first direction and a pair of thin portions which have a smaller thickness than the thick portion and are provided on opposite sides of the bottom portion along a second direction. The piezoelectric element radiates and/or detects ultrasonic energy and is provided at a center of the thick portion on an inner surface of the bottom portion.

Abstract: An ultrasonic inspection element and method of fabrication are provided for ultrasonic inspection of curved surface parts. Various points on a transducer are located. These points include the location where a ray starts, to the desired focal point in the material being inspected. The path of the ray is through a water medium and a water-metal boundary. These points are fitted onto a cylindrical surface. The ray is back propagated until it is focused at the desired focal point.

Abstract: An ultrasonic pulse echo inspection apparatus and method for detecting structural failures. A focus lens is coupled to the transducer to focus the ultrasonic signal on an area to be inspected and a stop is placed in the focus lens to block selected ultrasonic waves. Other waves are not blocked and are transmitted through the structure to arrive at interfaces therein concurrently to produce an echo response with significantly less distortion.

Abstract: A system includes a first transducer and a second transducer coupled together through a coupling medium communicating undulating pressure wave from the first transducer to the second transducer for the transfer of electrical power from an external controller energizing the first transducer transducing the power signal into an undulating pressure wave communicated through the medium to the second transducer traducing the undulating pressure wave into an electrical response signal that can be converted into useful power for powering an embedded sensory and actuation control unit. The primary advantage of the system is the transfer of power through a coupling medium without the use of electrical power wires.

Abstract: An ultrasonic probe includes an ultrasonic transducer; a delay line acoustically coupled to said transducer so that ultrasonic vibrations may be transmitted into said delay line from said ultrasonic transducer in a first direction, said delay line includes a first section and a second section; the first and second sections forming an interface that is substantially perpendicular to said first direction; and the second section including a surface for coupling with a material to be investigated. The probe can be used to measure a thickness of a coating on a substrate by transmitting a signal in a first direction from the transducer into the delay line; measuring a time t.sub.1 for a first portion of the signal to travel round trip from the transducer and the interface; using the measured time t.sub.1 to calculate an expected time t.sub.2 for a second portion of the signal to travel round trip from the transducer to an opposite face of the delay line; measuring a time t.sub.

Abstract: An ultrasonic transducer array having a plurality of transducer elements aligned along an array axis in an imaging plane. Each transducer element includes a piezoelectric layer and one or more acoustic matching layers. The piezoelectric layer has a concave front surface overlayed by a front electrode and a rear surface overlayed by a rear electrode. The shape of each transducer element is selected such that it is mechanically focused into the imaging plane. A backing support holds the plurality of transducer elements in a predetermined relationship along the array axis such that each element is mechanically focused in the imaging plane.

Abstract: A system includes a first transducer and a second transducer coupled together through a coupling medium communicating input and output undulating pressure waves between the first and second transducers for the transfer of input and output data between an external controller and an embedded sensory and actuating unit. The controller providing input data signals energizing the first transducer and the embedded unit providing output data signals energizing the second transducer collectively for bidirectional communication of data between the controller and embedded unit for functional sensor and actuator process control. The primary advantage of the system is the bidirectional transfer of data through a coupling medium without the use of electrical power wires for controlling embedded sensors and actuators.

Abstract: A generator for spherical ultrasonic waves can replace a point source transducer and has a large-area transducer whose output ultrasonic waves are condensed in a funnel and fed to a monomodal waveguide, e.g. a tube at the output end of which phase-correct perfectly spherical waves are emitted.

Abstract: An ultrasonic probe includes an ultrasonic transducer; a delay line acoustically coupled to said transducer so that ultrasonic vibrations may be transmitted into said delay line from said ultrasonic transducer in a first direction, said delay line includes a first section and a second section; the first and second sections forming an interface that is substantially perpendicular to said first direction; and the second section including a surface for coupling with a material to be investigated. The probe can be used to measure a thickness of a coating on a substrate by transmitting a signal in a first direction from the transducer into the delay line; measuring a time t.sub.1 for a first portion of the signal to travel round trip from the transducer and the interface; using the measured time t.sub.1 to calculate an expected time t.sub.2 for a second portion of the signal to travel round trip from the transducer to an opposite face of the delay line; measuring a time t.sub.

Abstract: A two-dimensional ultrasonic transducer for forming images. The transducer has a plurality of transducer elements for producing ultrasonic bursts in a predetermined manner, and receiving reflected ultrasound from the subject under examination due to the ultrasonic bursts. The plurality of transducer elements are arranged in an array into columns and rows, the columns of the transducer elements arranged in a scanning plane for scanning the subject under examination in order to form a two-dimensional profile of the subject, and the rows of the transducer elements having groups of symmetrically arranged transducer elements being oriented in a elevational plane. Each of the groups of symmetrically arranged transducer elements are mechanically arranged to have a focus at specified locations distant from the transducer which is within the subject under examination.

Abstract: An ultrasonic transducer array, and a method for manufacturing it, having a plurality of transducer elements aligned along an array axis in an imaging plane. Each transducer element includes a piezoelectric layer and one or more acoustic matching layers. The piezoelectric layer has a concave front surface overlayed by a front electrode and a rear surface overlayed by a rear electrode. The shape of each transducer element is selected such that it is mechanically focused into the imaging plane. A backing support holds the plurality of transducer elements in a predetermined relationship along the array axis such that each element is mechanically focused in the imaging plane.

Abstract: The sonic or ultrasonic transducer includes a circular piezo-ceramic disk capable of generating radial oscillations, and a metal ring, which embraces in tight close fitting relationship the circumferential surface area of the disk to form a radial oscillator in conjunction with the disk. The sonic or ultrasonic transducer formed in this manner has an emission surface corresponding to the entire surface area of the piezo-ceramic disk and metal ring, and displays a radial resonant frequency which is lower than that of the piezo-ceramic disk.

Abstract: An ultrasonic railhead investigating apparatus is described wherein a side looking transducer is used with a lens to focus the beam in a manner whereby rail defects in the sides of rail head are more readily detected. In one form of the invention a side rail investigating transducer is provided with a curved emitting surface and so located as to place the focused acoustic beam between a side of the rail and the rail center. The curved emitting surface can be part of a cylindrical surface aligned parallel with the longitudinal axis of the rail or a spherically shaped emitting surface to provide a conically shaped beam for investigating the side of a rail.

Abstract: An ultrasonic transducer having a transducer element which generates ultrasonic energy propagating along a transducer axis with a predetermined speed of propagation, and a lens acoustically coupled to the transducer element and having an input face positioned to receive the ultrasonic energy, wherein the lens includes electrorheological fluid with voltage dependent acoustic properties therein for enabling the speed of propagation to be selectively controlled as the ultrasonic energy passes through the lens. The transducer may include a focusing lens, a steering lens, or a combination thereof for selectively controlling the focusing and/or steering of the ultrasonic energy within a region of interest in an object to be inspected therewith. A voltage control device is used to controllably apply voltage to the lens to control the propagation speed as the ultrasonic energy passes therethrough.

Abstract: Method for scanning a field of view using a scan format, wherein the carrier frequency of the imaging pulse is higher in the center of the field of view than at the edges. The frequency variation can be accomplished on transmit by modulating appropriately delayed programmable initial waveform information samples with a programmable carrier frequency. This results in a pulse transmitted into the body whose frequency is highest in the center portion of the scan, and is reduced in a controlled fashion as the steering angle is increased in order to mitigate grating lobe artifacts. The technique preserves signal energy because modulation merely translates the signal in frequency substantially without modification of the pulse shape itself.

Abstract: An acoustic lens system is constructed so that at least one surface of acoustic lenses constituting the acoustic lens system is an aspherical surface, which has such a shape that curvature moderates progressively in separating from the axis of the acoustic lens system, and an acoustic beam stop is provided therein. As a result, aberrations can be favorably corrected even when the angle of view and the numerical aperture are increased and this brings about the acoustic lens system suitable for an objective lens of an acoustic system for securing an image of an object having a two-dimensional size in particular.

Abstract: An ultrasonic transducer having a transducer element which generates ultrasonic energy propagating along a transducer axis with a predetermined speed of propagation, and a lens acoustically coupled to the transducer element and having an input face positioned to receive the ultrasonic energy, wherein the lens includes electrorheological fluid with voltage dependent acoustic properties therein for enabling the speed of propagation to be selectively controlled as the ultrasonic energy passes through the lens. The transducer may include a focusing lens, a steering lens, or a combination thereof for selectively controlling the focusing and/or steering of the ultrasonic energy within a region of interest in an object to be inspected therewith. A voltage control device is used to controllably apply voltage to the lens to control the propagation speed as the ultrasonic energy passes therethrough.

Abstract: The invention relates to an ultrasonic process for testing, by immersion, the soundness of a metal piece (26) using at least one transducer (21) emitting ultrasonic waves focused in the piece (26). There are a plurality of transducers (21) used. Each of the transducers having in the tested piece (26) a focal spot at -6 dB, the section of which, perpendicular to the axis of propagation of the waves is less than 40 mm2. The focal spots of the transducers (21) being distributed depending on the depth to be tested of the piece (26). Additionally, the invention describes a process to guarantee the soundness of the interior of a piece (26), in particular a bar made of a titanium alloy (26) of a diameter of between about 50 and 400 mm for use in aeronautics.

Abstract: An ultrasonic transducer with a magnetostrictive lens for dynamically focussing and steering a beam of ultrasound energy is provided. The magnetostrictive lens is operable in response to a magnetic field generated by a coil such that the speed of propagation of the ultrasound beam is selectively controlled as the beam passes through the lens. The lens can be made up of first and second prisms wherein at least one of such prisms is magnetostrictive. Alternatively, the lens can be made up of an individual stage made of a composite having a plurality of elongated rods of magnetostrictive material cooperating in response to the control signal applied to the lens for selectively controlling the propagation speed of the ultrasound beam passing therethrough.

Abstract: A probe 10 and method for measuring a gaseous material, such as air, entrained in a solution (S) has a protective sheath member 14 having an ultrasonic transducer 18 encased therein and a reflecting member 42 spatially separated from the active area of face 20 of transducer 18. Upon activation of transducer 18, ultrasonic waves are emitted from transducer 18 that reflect off the gaseous material in the form of bubbles 48 and reflecting member 42 thereby producing correspondingly associated backscattered signals therefrom. Accordingly, the backscattered measurement is operative at low entrained air levels when only a few bubbles or gas 48 are present. Scattering from reflecting member 42 is useful at higher entrained air levels, approaching foam.

Abstract: An ultrasonic parametric amplifier incorporates a duct having rigid cylindrical wall with a periodic inner surface that undulates sinusoidally in an axial direction, and an element for heating the external surface of the wall. The sinusoidal undulations of the periodic inner surface have a wavelength which is about half of the wavelength of the waves of ultrasonic energy propagating through a fluid filling the duct. The waves are amplified by synergistic interactions of the ultrasonic waves with the periodic duct walls when heat is added in a predetermined manner, thereby compensating for the exponential decrease in fluid temperature which would otherwise lead to detuning of the amplifier.

Abstract: An ultrasonic transducer array, and a method for manufacturing it, having a plurality of transducer elements aligned along an array axis in an imaging plane. Each transducer element includes a piezoelectric layer and one or more acoustic matching layers. The piezoelectric layer has a concave front surface overlayed by a front electrode and a rear surface overlayed by a rear electrode. The shape of each transducer element is selected such that it is mechanically focused into the imaging plane. A backing support holds the plurality of transducer elements in a predetermined relationship along the array axis such that each element is mechanically focused in the imaging plane.

Abstract: An ultrasonic measurement device and a method for a non-destructive evaluation of polymer composites having discontinuous fibers distributed therein. The device has one or a plurality of substantially matched pairs of transducers disposed on wedge shaped focuser and a relay, the focuser and relay each have their impedances substantially matched to that of the polymer composite being analyzed. The device is placed on a surface of the composite with the apexes of the focuser and relay in close contact with the surface.

Abstract: A transducer for generating or detecting ultrasonic energy of very narrow bandwidth which closely approximates a monochromatic source or detector has a gas gap of uniform dimensional width. The transducer employs standing ultrasonic waves generated, by multiple reflections and constructive interference, within the gap, effectively acting as a filter to pass only ultrasonic waves having a predetermined resonant frequency in response to impingement of broadband ultrasonic energy. This filtering effect enables the transducer to act as a source or detector of monochromatic ultrasound.

Abstract: An acoustic lens system is constructed so that at least one surface of acoustic lenses constituting the acoustic lens system is an aspherical surface, which has such a shape that curvature moderates progressively in separating from the axis of the acoustic lens system, and an acoustic beam stop is provided therein. As a result, aberrations can be favorable corrected even when the angle of view and the numerical aperture are increased and this brings about the acoustic lens system suitable for an objective lens of an acoustic system for securing an image of an object having a two-dimensional size in particular.

Abstract: A cylindrical ultrasonic transducer (36) is disclosed. The transducer includes a cylindrical main element (38) provided with a plurality of ring-shaped secondary elements (40 and 42) that are triangular in cross section. By controlling the number, geometry, and construction of the secondary elements, substantially any desired ultrasonic emission pattern can be produced while maintaining a low overall transducer profile.

Abstract: The invention includes a means and method for transmitting and receiving broadband, unipolar, ultrasonic pulses for ultrasonic inspection. The method comprises generating a generally unipolar ultrasonic stress pulse from a low impedance voltage pulse transmitter along a low impedance electrical pathway to an ultrasonic transducer, and receiving the reflected echo of the pulse by the transducer, converting it to a voltage signal, and passing it through a high impedance electrical pathway to an output. The means utilizes electrical components according to the method. The means and method allow a single transducer to be used in a pulse/echo mode, and facilitates alternatingly transmitting and receiving the broadband, unipolar, ultrasonic pulses.

Abstract: An apparatus for measuring the flow of a fluid in a pipe using ultrasonic waves. The apparatus comprises an ultrasonic generator, a lens for focusing the sound energy produced by the generator, and means for directing the focused energy into the side of the pipe through an opening and in a direction close to parallel to the long axis of the pipe. A cone carries the sound energy to the lens from the generator. Depending on the choice of materials, there may be a quarter-wave, acoustic impedance matching section between the generator and the cone to reduce the reflections of energy at the cone boundary. The lens material has an acoustic impedance similar to that of the cone material but a different sonic velocity so that the lens can converge the sound waves in the fluid. A transition section between the lens and the fluid helps to couple the energy to the fluid and assures it is directed as close to parallel to the fluid flow direction as possible.

Abstract: A preferred embodiment of a large diameter solid ultrasonic imaging transducer is illustrated in FIG. 5 with alternate embodiments illustrated in FIGS. 6-9. The large diameter solid ultrasonic imaging lens 100 has a diameter preferably greater than six inches with a focal length-to-diameter ratio of between 1 and 2. The lens 100 has concave surfaces 108 and 110, and is composed of a homogenous material that has an ultrasonic impedance of less than twice that of water and has a density less than the water. Preferably, the velocity of the ultrasonic sound through homogenous plastic material is less than twice that of water. One or both of the concave surfaces 108 and 110 have surfaces that are without a constant radius and curvature, but however are composed of separate radius of curvatures for each small increment of lens surface to properly focus the ultrasound at a desired focal length "L".An alternate embodiment is illustrated in FIG.

Abstract: A scanning acoustic microscope of the present invention comprises a high frequency transmitter for transmitting high frequency signal, first electric/ acoustic conversion element for converting the high frequency signal to ultrasound, acoustic lens having an end surface to which the ultrasound is incident and a concave lens surface to which the incident ultrasound is exited, an ultrasound receiver having a flat receiving surface located in an opposed relation to the concave lens surface to allow the transmission of only that ultrasound substantially vertically incident to the receiving surface, second electric/acoustic conversion element for converting ultrasound which has been transmitted through the ultrasound receiver to an electric signal, and an image processing circuit for preparing an image in accordance with a reception signal delivered from the second electric/acoustic conversion element.

Abstract: A focused acoustic transducer for use with a borehole televiewer wherein the transducer is provided with a concaved surface designed to focus the acoustic energy and reduce the energy present in the side lobes of the near field.

Abstract: There is disclosed an ultrasonic shockwave transducer for use in lithotripsy, hypothermia and like treatments for generating ultrasonic shock waves and transmitting them to a concretion or tissue to be destroyed. The transducer is arranged to focus the energy of the ultrasonic shock waves proportionally onto at least two points disposed on a line disposed about the main axis of, and being spaced from the radiation surface of, the transducer, the line being arbitrarily curved in three dimensions.

Abstract: A transducer assembly, suitable for medical examinations, for generating an apodized sector shaped beam of energy. A transducer in the form of a crystal, has a ring-like structure on its face which apodizes the signal produced by the transducer by providing a greater amount of attenuation at the transducer's periphery than at the transducer's center.

Abstract: An improved method is proposed for the image information of a body by ultrasonic scanning in which the resolution of the image can be greatly improved without sacrifice in the penetrability of the ultrasonic waves, i.e. without increasing the ultrasonic frequency, into the body under inspection.The improvement comprises:attaching a central ultrasonic absorber to the ultrasonic objective lens of the ultrasonic probe; andinserting an auxiliary concave lens between the ultrasonic probe and the body under inspection.

Abstract: An ultrasonic probe system is disclosed, which is designed to allow connection of a DC power supply capable of applying a voltage higher than the coercive electric field of each of a plurality of piezoelectric layers thereto, and includes a polarization turn over circuit means for, when the DC power supply is driven, turning over the polarity of the DC power supply so as to direct electric fields of every two adjacent layers constituting the piezoelectric layers in substantially opposite directions or electric fields of all the layers in the same direction.

Abstract: A conical ultrasonic wave deflection system has an ultrasonic transducer for ultrasonic microscopy using surface waves and/or Lamb waves in an object. A conical wave front is directed onto the object via a deflection element. An inactive axial circular disk is provided between the ultrasonic transducer and the object to minimize unnecessary interference from undeflected waves. A frustoconical lens with a blocked top face, or a conical metal reflector with a ring transducer on the transducer side can be provided as the deflection element. The arrangement is highly compatible with ultrasonic microscopes. Matching to a critical angle .theta. of the object is achieved by selection of the appropriate ultrasonic frequency.

Abstract: A high-frequency signal is applied from an oscillator via a circulator to a piezoelectric transducer. An ultrasonic wave generated by the piezoelectric transducer is directed to a material through an acoustic lens. The ultrasonic wave transmitted through the material is conducted to a phase-conjugator having a nonlinear piezoelectric element consisting of a crystal of LiNbO.sub.3. A phase-conjugate wave generated by the generating section is transmitted through the material again and received by the piezoelectric transducer. The received signal is supplied to a receiver circuit via the circulator. The receiver circuit gates the received signal in accordance with a time of return of the phase-conjugate wave so as to extract a signal representing the interior of the material. The material is scanned two-dimensionally by a scanning control device so as to display a two-dimensional ultrasonic image on a television monitor.

Abstract: An acoustic microscope in which acoustic energy is focused onto a membrane which includes an aperture which is a fraction of the size of the focal spot of the acoustic beam at the membrane to form fringing fields on the other side of the membrane. Acoustic energy reflected from the membrane is detected. An object to be examined is placed in cooperative relationship with the fringing fields.

Abstract: An ultrasonic flaw inspecting apparatus is provided in which the transmission signals comprising N number of the binary code sequences having sharp autocorrelation functions are input to an object to be inspected by a single transducer for transmission and the reflected signals are received by N number of transducers for reception. The N number of transducers for reception are connected and placed over each other so that the direction of respective polarization is inverted in terms of the time order of the binary code of the sequence.

Abstract: A probe for an ultrasonic microscope is disclosed. The probe has an element for radiating and receiving an ultrasonic wave and an acoustic lens for causing an ultrasonic wave, which has been generated by the element, to converge at a point into an ultrasonic beam, whereby the ultrasonic beam is radiated against a sample and a reflected wave of the thus-radiated ultrasonic beam is received by the element to convert the reflected wave into an electrical signal proportional to the reflected wave. A mask is provided on a side of the sample relative to the acoustic lens. The mask is composed of an ultrasonic wave transmitting portion and an ultrasonic wave blocking portion. The transmitting portion permits the transmission of first beam components, which take part in producing an elastic surface wave in one direction in a surface layer of the sample, and second beam components which take no part in the production of any elastic surface wave.

Abstract: An ultrasonic testing method for detection of flaws in a material to be tested having a curved surface portion by use of an ultrasonic probe, wherein a center axis of curvature of the curved surface portion of the material to be tested and the center axis of the probe are set in an eccentric relationship so that the angle of refraction of an ultrasonic wave is 90.degree., and the probe comprises a tip portion having a curved surface of the same kind as the curved surface portion of the material to be tested and a radius of curvature of from 1.0 to 3.0 times the radius of curvature of the curved surface portion of the material to be tested. The method enables detection of internal flaws in, particularly, a spherical or cylindrical body formed of a ceramic and used as a bearing member.

Abstract: The present invention is directed to a method for determining, by a condensation method, the vapor pressure of a material with a known vapor pressure versus temperature characteristic, in a flow system particularly in a mercury isotope enrichment process.

Abstract: An ultrasonic probe comprising an acoustic lens (20) having a concave lens surface (21) formed on one side of a lens body, and a piezoelectric transducer (23) disposed on the other side of the acoustic lens, ultrasonic waves generated by applying voltage to the piezoelectric transducer being focused through the lens surface to detect the reflected waves of the ultrasonic waves from a sample (26) by the piezoelectric transducer for obtaining information about the surface or interior of the sample. The lens surface (21) of the acoustic lens (20) is defined by an etch profile (15) formed by etching a substrate material (11) which makes up the lens body.

Abstract: Apparatus and methods for determining the Reid Vapor Pressure of either an overhead, side draw or bottoms product stream of a fractionating column used for fractionating a multi-component hydrocarbon feed stream into an overhead product stream, a side draw product stream and a bottoms product stream are provided. The Reid Vapor Pressure of the particular product stream is determined in response to the temperature of the product stream, the vapor pressure of the product stream, the rate of flow of the bottoms product stream, the rate of flow of the overhead product stream, and/or the rate of flow of the side draw product stream without further analyses thereof. The Reid Vapor Pressure indication is used to maintain the actual Reid Vapor Pressure of the particular product stream substantially equal to the desired Reid Vapor Pressure of the particular product stream and to thereby control the quality of the desired product stream.

Abstract: A device is disclosed which allows an object to be tuned to an incoming sound wave magnitude and wavelength, such that the sound wave will alternatively be passed therethrough without detectable reflection or be completely reflected. The apparatus is intended to be mounted within a hollow object and adjust the perceived distance between the exterior walls of that object to mimic a single thick wall. A signal processing means is supplied which detects the sound wave magnitude and wavelength impinging on the wall facing the sound wave source. The wavelength is passed to the signal processing means, which transmits a complimentary signal to the second wall of the hollow object. The complimentary signal allows the hollow object to resonate as a whole as if it were a solid of a thickness much different from its actual thickness, allowing the sound wave to pass undisturbed therethrough or be reflected therefrom.

Abstract: An ultrasonic testing method comprises steps of transmitting an ultrasonic wave from a probe to a test article, detecting an internal flaw in the test article by a reflected flaw echo from the internal flaw, and deciding a condition of the detected flaw by comparing and analyzing frequency components of the transmitted ultrasonic wave and the reflected flaw echo. The probe has a curved tip surface which is the same kind as that of a curved incident surface of the test article and has a radius of curvature of 0.5.about.2.0 times the radius of curvature of the curved incident surface of the test article.

Abstract: An apparatus comprising a chemically sensitive sensor material, having an electrical resistance or dielectric constant which changes under the effect of the gases or vapors. According to the invention, this sensor material, which comprises either hydrophobic metal complexes, or a mixture of at least one phthalide and at least one acidic compound, serves as resistance or as dielectric material. These sensor materials change their ion mobility and/or their ionic concentration under the effect of gases or vapors, thereby changing their resistance or capacitance. The change in resistance or the change in capacitance can expediently be converted into a frequency change by a multivibrator. Thus, one obtains an especially simple and very effective sensor for gases and vapors.