Abstract: A flaw detection system using acoustic Doppler effect for detecting flaws in a medium wherein there is relative motion between the medium and system includes a transducer, spaced from the medium to be inspected, for introducing to and sensing from the medium an acoustic signal that propagates in the medium at a predetermined frequency; and a detector, responsive to the sensed propagating acoustic signal, for detecting in the sensed acoustic signal the Doppler shifted frequency representative of a flaw in the medium.

Abstract: A method for detecting the presence of particles, such as sand, flowing within a fluid in a conduit is disclosed. At least two optical sensors measure pressure variations propagating through the fluid. These pressure variations are caused by acoustic noise generated by typical background noises of the well production environment and from sand particles flowing within the fluid. If the acoustics are sufficiently energetic with respect to other disturbances, the signals provided by the sensors will form an acoustic ridge on a k? plot, where each data point represents the power of the acoustic wave corresponding to that particular wave number and temporal frequency. A sand metric then compares the average power of the data points forming the acoustic ridge to the average power of the data points falling outside of the acoustic ridge. The result of this comparison allows one to determine whether particles are present within the fluid.

Abstract: A method and apparatus are provided for performing non-contact inspection of large concrete structures such as dams. A phrased array acoustic source transmits an acoustic wave onto the concrete structure. A laser transmitter-receiver unit transmits a laser beam onto the surface of the structure such that the beam is modulated by the acoustic wave and reflected back to the receiver portion of the unit. The acoustic wave will be distorted by defects or anomalies in the concrete structure and this will affect the signal content of the received laser beam. The laser beam is ultimately converted into a two-dimensional image or a three-dimensional tomographic image for further processing.

Abstract: In a method for ultrasonic testing of objects, ultrasound is generated inside or at the surface of the object. The surface of the object is illuminated with a beam from a long-pulse laser oscillator, typically in the range 1 &mgr;s to a few 100 &mgr;s, that is substantially free of intensity fluctuations. The light from the incident beam that is scattered or reflected by the surface of the object is collected and demodulated to obtain a signal representative of the ultrasonic motion. The method allows for the use of a compact and efficient arrangement.

Abstract: The present invention uses the generation and detection of acoustic guided waves to evaluate the condition of the insulation on electrical wiring. Low order axisymmetric and flexural acoustic modes are generated in the insulated wire and travel partially in the center conductor and partially in the outer insulation. The stiffness of the insulation and the insulation's condition affect the overall wave speed and amplitude of the guided wave. Analysis of the received signal provides information about the age or useful life of the wire insulation. In accordance with the present invention, signal transmission occurs at one location on the electrical wire to be evaluated, and detection occurs at one or more locations along the electrical wire. Additional receivers can be used to improve measurement accuracy. Either the transmission transducer or one or more receiver transducers may be angled at other than 90 degrees to the wire.

Abstract: The product comprises a sensor (1) via which a measured quantity that corresponds to a reactive resistance can be furnished within a measuring range. The product also comprises a matching network (2) and a surface wave element (3). The sensor (1) is connected to a first reflector (4) of the surface wave element (3) via the matching network (2). The first reflector (4) forms, together with the matching network (2) and the sensor (1), a resonator which, for a value of the measured quantity within the measuring range, has a resonance with regard to a reflection of an acoustic surface wave on the first reflector (4). The invention also relates to a method for determining the measured quantity and to a corresponding system.

Abstract: The present invention relates to an electromagnetic ultrasonic transducer for generating horizontally polarized transverse waves. The transducer comprises a coil support (4) which is made of a material having good magnetic conductivity and which is provided with a comb-like structure having parallel running channels (5) and fins (6). A plurality of HF coils (1) which are electrically interconnected in series are wound on at least some of said fins 6 at some distance the faces of said fins (6) with adjacent coils (1) having an alternating direction of wind. In the channels (5) are arranged a plurality of rows (3) of permanent magnets (2) having alternating pole assignment. With the present ultrasonic transducer, in particular low-frequency SH waves can be generated in or receiving out of electrically conductive materials without the risk of wearing the HF coils.

Abstract: A method and apparatus for nondestructive testing a railroad rail is provided. The method includes locating at least one magnetic exciter adjacent to the rail, the at least one magnetic exciter includes an emitting end and a longitudinal axis extending perpendicularly through the emitting end, discharging the energy storage circuit through the at least one magnetic exciter such that only a magnetic pulse enters the rail at a location of the exciter, and controlling a shape of the magnetic pulse. The apparatus includes at least one magnetic exciter adjacent to a rail, a energy storage circuit electrically coupled to the at least one magnetic exciter the energy storage circuit is configured to supply a shaped current pulse to the at least one exciter, and a power source electrically coupled to the energy storage circuit.

Abstract: A method and apparatus is shown for implementing magnetostrictive sensor techniques for the nondestructive evaluation of pipes or tubes. A magnetostrictive sensor generates guided waves in a pipe or tube, which waves travel therethrough in a direction parallel to the longitudinal axis of the pipe or tube. This is achieved by using a magnetized ferromagnetic strip being pressed circumferentially against the pipe or tube. For improved efficiency, the strip may be made from an iron-cobalt alloy. The guided waves are generated in the strip and coupled to the pipe or tube and propagate along the length of said pipe or tube. For detection, the guided waves in said pipe or tube are coupled to the thin ferromagnetic strip and are detected by receiving MsS coils. Reflected guided waves may represent defects in the pipe or tube.

Abstract: In industrial sensing applications at least one parameter of at least one fluid in a pipe 12 is measured using a spatial array of acoustic pressure sensors 14,16,18 placed at predetermined axial locations x1, x2, x3 along the pipe 12. The pressure sensors 14,16,18 provide acoustic pressure signals P1(t), P2(t), P3(t) on lines 20,22,24 which are provided to signal processing logic 60 which determines the speed of sound amix of the fluid (or mixture) in the pipe 12 using acoustic spatial array signal processing techniques with the direction of propagation of the acoustic signals along the longitudinal axis of the pipe 12. Numerous spatial array-processing techniques may be employed to determine the speed of sound amix. The speed of sound amix is provided to logic 48, which calculates the percent composition of the mixture, e.g., water fraction, or any other parameter of the mixture, or fluid, which is related to the sound speed amix. The logic 60 may also determine the Mach number Mx of the fluid.

Abstract: An improved photoacoustic vessel and method of photoacoustic analysis. The photoacoustic sample vessel comprises an acoustic detector, an acoustic couplant, and an acoustic coupler having a chamber for holding the acoustic couplant and a sample. The acoustic couplant is selected from the group consisting of liquid, solid, and combinations thereof. Passing electromagnetic energy through the sample generates an acoustic signal within the sample, whereby the acoustic signal propagates through the sample to and through the acoustic couplant to the acoustic detector.

Abstract: A method and apparatus for nondestructive testing a railroad rail is provided. The method includes locating at least one magnetic exciter adjacent to the rail, the at least one magnetic exciter includes an emitting end and a longitudinal axis extending perpendicularly through the emitting end, discharging the energy storage circuit through the at least one magnetic exciter such that only a magnetic pulse enters the rail at a location of the exciter, and controlling a shape of the magnetic pulse. The apparatus includes at least one magnetic exciter adjacent to a rail, a energy storage circuit electrically coupled to the at least one magnetic exciter, the energy storage circuit is configured to supply a shaped current pulse to the at least one exciter, and a power source electrically coupled to the energy storage circuit.

Abstract: An apparatus and method for inspecting a structure are provided in which probes including respective sensing elements, such as ultrasonic transducers, are disposed proximate the opposed surfaces of a structure, but only one of the probes need be driven. In this regard, a tracking probe may be magnetically coupled to a driven probe and move in coordination therewith. The apparatus and method can therefore inspect structures in which one surface is inaccessible. The probes may permit liquid to be bubbled between the ultrasonic transducer and the structure in order to couple the ultrasonic signals. By utilizing a bubbled liquid as a couplant, the apparatus and method may operate in an ultrasonic array mode. Additionally, the probes may include at least one contact member, such as a plurality of wheels, for contacting the structure in order to maintain the desired orientation and spacing of the probes relative to the structure.

Abstract: A system for identifying ultrasonic displacements in a material under test utilizing a time-varying output pulse of a first laser beam. The system includes a seed laser light source for providing a laser beam, a modulating assembly in the path of propagation of the laser beam for time-varying of the laser beam, at least one optical isolation assembly placed in the path of propagation of the laser beam for preventing reflected laser light feedback into the seed laser light source, and at least one laser light amplification assembly placed in the path of propagation of the laser beam for amplifying the laser beam which passes the amplified time-varying output pulse of the laser beam.

Abstract: An automated metrology system for photoacoustic measurement of single or multi-layer films, and a method of making the system, are disclosed. Dramatic improvements in the cost of ownership of the system is attained by making the system scalable from a system having a single metrology sub-system for making measurements, to a system having two, vertically stacked metrology sub-systems for making independent measurements. A front end of the system for storing multiple cassettes comprises a robot having vertical travel capable of transferring cassettes to and from each of the first and second metrology sub-systems in the case the system is expanded. The two metrology sub-systems are preferably identical and share much of the optics, a computer as well as the front end of the system. Throughput of the dual system is 1.75-2 times greater than that of a single tool metrology system while the cost is substantially less than two complete single tool metrology systems.

Abstract: The invention includes a particle detection system that detects bioparticles in a sample utilizing a sensor device that receives photoacoustic signals from a sample. The invention includes a system for distinguishing biologically active particles from non-biologically active particles in a sample utilizing a transducer to receive a laser induced photoacoustic signal from the sample and a fluorescence detector to receive laser induced fluorescence. The invention includes a method of screening a sample for the presence of one or more particle types by subjecting a sample to laser light and measuring at least one photonic response and at least one acoustic response are measured from the sample to produce a sample composite data set which is compared to a signature data set from a control sample. The invention also includes methods for detecting a change in the particle composition within a test area.

Abstract: The invention provides an acoustic diagnosis/measurement apparatus/method using a pulse of electromagnetic force, capable of non-destructively and precisely diagnosing or measuring corrosion, adhesion, the. cover depth, and/or the diameter of a reinforcing iron rod in a structure made of reinforced concrete. A coil 12 is attached to a surface of a structure 11 including a conductor 11a and a non-conductive material 11b covering the conductor 11a. A current pulse is applied to the coil 12 thereby generating a magnetic field pulse. The magnetic field pulse causes an eddy current to be induced in the conductor 11a. The conductor 11a is oscillated by interaction between the eddy current and the magnetic field pulse. As a result, an acoustic signal is generated by the conductor 11a and the acoustic signal is converted into an eclectic signal by an acoustic transducer 14 disposed to the surface of the structure 11.

Abstract: A performance measuring system for a rotating shaft comprises a first annular support assembly to be coupled adjacent to a first end of a rotating shaft inwardly of associated shaft bearings. A second annular support assembly is to be coupled adjacent to a second end of a rotating shaft inwardly of associated shaft bearings. A third annular support assembly is to be coupled to the rotating shaft between the first and second support assemblies. A laser source is mounted on the first annular support assembly. A laser detector is mounted on the second annular support assembly. First and second magnetic sensors for detecting the Earth's magnetic field are mounted respectively on the first and second annular support assemblies. An accelerometer is mounted on the third annular support assembly for generating a fourth detection signal.

Abstract: A system and method for testing a physical attribute of a manufactured object that includes a laser generator and pulse generator that generate a plurality of Dirac-like pulses. The pulses, directed at an object, cause a sonic signal to be initiated indicative of the physical attribute of the manufactured object, and are detected. The system also controls the width of the Dirac-like pulses and time separation between pulses. A display may also be used to present the detected signal or physical attribute. The Dirac-like pulses are structured to produce a particular output in the manufactured object. The Dirac-like pulses may be altered dynamically in the presence of deviations from the expected output. One embodiment of the Dirac-like pulses is a series of pulses with pulse widths less than 20% a time separation between successive pulses.

Abstract: An ultrasonic transducer is provided having a transduction element in the form of a truncated cone. The angle of the transduction element is selected so that the majority of the acoustic energy incident on the target is refracted beyond the longitudinal critical angle, which minimizes contamination of the inspection results.

Abstract: A photoreceiver assembly for accurately separating at least one low level, high frequency signal carried from a large, low frequency pulse. Illustratively, in one exemplary embodiment, the photoreceiver assembly extracts a high frequency ultrasonic signal from the optical frequency of light by shining that ultrasonic base band signal onto a photodetector for conversion into an electrical signal in the bandwidth of interest. The photoreceiver assembly includes a photodetector and a splitter coupled to the photodetector. The splitter is also coupled to a plurality of transimpedance signal paths. In operation, the splitter receives a current from the photodetector, separates, and directs the current to the plurality of transimpedance signal paths. In one exemplarily embodiment, the photoreceiver further includes a transimpedance amplifier assembly coupled to at least one path of the transimpedance signal paths.

Abstract: The disclosed invention mounts transmitting and receiving electrical coils within channels or chambers formed by the notched ends of magnets closest to the metallic object under test where said magnets are arranged to form substantially annular arrays of an electromagnetic acoustic transducer pair applicable in non-destructive testing. The detection, preferably by tuned coils, of one or more electromagnetically-induced resonant frequencies at shifted locations indicates the presence of one or more flaws in the metallic structure under test.

Abstract: Electromagnetic acoustic resonance method by using EMAT is used for determining hydrogen concentration of radioactive metallic object. In one preferred embodiment, resonance frequencies fr, fr are measured with the EMAT, where where fr is a resonance frequency when a direction of an amplitude of a transverse ultrasonic wave generated by the EMAT is the same as the rolling direction of the metallic object of rolled material, and ft is a resonance frequency when a direction of the amplitude of the transverse ultrasonic wave is perpendicular to the rolling direction. A value R is calculated by using: R=(fr−ft)/{(fr+ft)/2}. The hydrogen concentration of the metallic object is calculated on the basis of the experimentally determined relation between the value R and hydrogen concentration.

Abstract: The invention relates to a transmitting system for the generation of ultrasonic waves for testing materials, comprising a controllable signal generator and an ultrasonic transducer, wherein the signal generator and the ultrasonic transducer are arranged in the immediate vicinity of one another, in order to provide a transmitting system for ultrasonic testing which has higher effectiveness and lower manufacturing costs than known transmitting systems.

Abstract: A method for quality control monitoring of laser shock peening a surface of a production workpiece during which laser beam pulses form a plurality of corresponding plasmas. An acoustic signal of each laser beam pulse during a period of time during a duration of each corresponding one of the plasmas is monitored and an acoustic energy parameter value for each of the acoustic signals for each of the corresponding laser pulses is calculated. A statistical function value of the workpiece based on the acoustic energy parameter values is calculated and compared to a pass or fail criteria for accepting or rejecting the workpiece. The criteria may be based on a pre-determined correlation of test piece statistical function data such as high cycle fatigue failure data of test pieces. The statistical function value may be an average of the acoustic energy parameter values of the laser beam pulses.

Abstract: A method and apparatus is shown for implementing magnetostrictive sensor techniques for the nondestructive evaluation of ferromagnetic pipes or tubes. A magnetostrictive sensor generates shear waves and/or torsional waves in ferromagnetic pipes or tubes, which waves travel therethrough in a direction parallel to the longitudinal axis of the pipe. A circumferential magnetization is generated in the ferromagnetic pipe or tube by a DC or low frequency voltage establishing a current along the longitudinal axis and past the magnetostrictive sensor. Reflected shear or torsional waves may represent defects in the pipe or tube.

Abstract: In a method for ultrasonic testing of objects, ultrasound is generated inside or at the surface of the object. The surface of the object is illuminated with a beam from a long-pulse laser oscillator, typically in the range 1 &mgr;s to a few 100 &mgr;s, that is substantially free of intensity fluctuations. The light from the incident beam that is scattered or reflected by the surface of the object is collected and demodulated to obtain a signal representative of the ultrasonic motion. The method allows for the use of a compact and efficient arrangement.

Abstract: A crack detection method and system capable of detecting cracks on a scale of about 5 &mgr;m or greater, useful for detecting cracks in sol-gel tubes. An electromagnetic radiation signal is transmitted from a sensor to a body in which cracking may occur. The signal is reflected back to and received by the sensor. An output voltage from the sensor is measured which is proportional to a signal characteristic change between the transmitted and received signals. Signal characteristics such as frequency, phase, and amplitude may be monitored. The signal characteristic change may result from one or more mechanisms selected from the group consisting of microscopic motion of the body, media transition and fluid movement.

Abstract: The present invention relates to an electromagnetic ultrasonic transducer for generating horizontally polarized transverse waves. The transducer comprises a coil support (4) which is made of a material having good magnetic conductivity and which is provided with a comb-like structure having parallel running channels (5) and fins (6). A plurality of HF coils (1) which are electrically interconnected in series are wound on at least some of said fins 6 at some distance the faces of said fins (6) with adjacent coils (1) having an alternating direction of wind. In the channels (5) are arranged a plurality of rows (3) of permanent magnets (2) having alternating pole assignment.

Abstract: A two-dimensional ultrasonic probe has a transmitting function of an ultrasonic signal without electric interconnection of a numerous number of microcomponents and without increase in crosstalk and electric impedance. This probe includes an optical fiber array having a plurality of optical fibers to which light generated from a light source is made incident, a plurality of ultrasonic detecting elements, formed at one ends of the respective optical fibers, for modulating incident light via the optical fibers on the basis of the ultrasonic signal to be applied, and an ultrasonic transmitting element using a piezoelectric element.

Abstract: An invention to measure of objects of non-homogeneous ultrasonic impedance in the testing path is provided to detect the present of flaws in any part of the object. The invention utilized a reference signal to compare against the actual signal derived from ultrasonic testing of the object. Reference signals are determined based upon the known or calculated properties of the object's layers or previously obtained signals measured from the object.

Abstract: A method for determining the thickness and other properties of a metal layer comprising producing an acoustic wave at a first frequency in the metal layer with a first laser beam, measuring the angle of diffraction of a second laser beam from the acoustic wave, and calculating the wavelength of the acoustic wave and thickness of the metal layer from the angle of diffraction.

Abstract: A nondestructive inspection apparatus includes a vibrating section 11 which is adapted to be placed in pressure contact with a surface of a measuring object 16 for generating an acoustic elastic wave W, a receiving section 12 for receiving a reflected wave, a pushing mechanism 13 for pushing the vibrating section and the receiving section against the measuring object, a pushing force measurement section 14 for detecting pushing forces Fa, Fb during vibration, a vibration control section 10 for driving the vibrating section, and a reception signal processing section 15 for determining the internal defect based on a reception signal R.

Abstract: An acoustic nonlinearity parameter (&bgr;) measurement method and system for Non-Destructive Evaluation (NDE) of materials and structural members novelly employs a loosely mounted dielectric electrostatic ultrasonic transducer (DEUT) to receive and convert ultrasonic energy into an electrical signal which can be analyzed to determine the &bgr; of the test material. The dielectric material is ferroelectric with a high dielectric constant ∈. A computer-controlled measurement system coupled to the DEUT contains an excitation signal generator section and a measurement and analysis section. As a result, the DEUT measures the absolute particle displacement amplitudes in test material, leading to derivation of the nonlinearity parameter (&bgr;) without the costly, low field reliability methods of the prior art.

Abstract: A method for inspecting concrete structures includes the steps of exciting the structure to be inspected with a mechanical device such as a chain, sensing resulting vibrations with an acoustical sensor such as a microphone that is not physically coupled to the structure, processing the received signals to exclude signals with frequencies outside of response frequencies of interest corresponding to defects desired to be detected, and examining the received signals. In preferred embodiments, the mean square of the processed signals are compared to a threshold. Areas for which the total energy across the frequency bands of interest exceeds the threshold correspond to defects such as delaminations. The received signals are collected from various locations on the structure. In preferred embodiments, the location of the received signals is also maintained.

Abstract: A system and method for delivering a laser beam from a remote laser source through a gantry positioning system for performing ultrasonic testing on a test object. The invention provides for closed-loop error correction of a laser beam delivered through the gantry members of a gantry positioning system (GPS) to ensure unobstructed transmission of the laser beam as the GPS changes operates and changes shape. The invention provides for ultrasonic testing of a test object for identifying material defects by moving the end gantry member of the GPS thereby permitting data acquisition of the test object from various fields of view. The invention also provides for controlling the divergence of the laser beam used for ultrasonic testing.

Abstract: The disclosed invention mounts transmitting and receiving electrical coils (52, 54) within channels or chambers (48, 50) formed by the notched ends of magnets (24, 28) closest to the metallic structure under test (40) where said magnets (24, 28) are arranged to form annular arrays (20, 22) of an electromagnetic acoustic transducer (EMAT) pair applicable in non-destructive testing. The detection of one or more electromagnetically-induced resonant frequencies at shifted locations indicates the presence of one or more flaws (58, 60) in the metallic structure under test (40). The novel recessed mounting of the coils provided by the channels or chambers (48, 50) substantially reduces the observed electrical cross-talk between coils (52, 54) over the prior art and reduces the likelihood of the coils (52, 54) making contact with the subject metallic structure under test (40) as it is in longitudinal motion relative to the coils (52, 54).

Abstract: The present invention relates to a method and apparatus for detecting anomalies, defects or electromagnetic properties of electrically conductive and magnetically permeable materials by using a magnet to partially saturate the material, thereby lowering its permeability, and sending a second, higher frequency oscillating electromagnetic wave into the material. The oscillating magnetic flux field permeating into the electrically conductive material induces eddy waves. As the apparatus passes over the material, the properties of the induced eddy currents, and the corresponding magnetic flux field induced by such eddy currents, changes as the properties of the material change. These changes can be the result of defects or anomalies in the material or in connecting welds.

Abstract: A method and an apparatus for non-contact and non-invasive characterization of a moving thin sheet and in particular of a paper web on a production line. The method uses a laser for the generation of sonic and ultrasonic waves in the thin sheet and a speckle insensitive interferometric device for the detection of these waves. The generation is performed in conditions to avoid damage impeding further use of the sheet. When the generation and detection spots overlap, the method provides a measurement of the compression modulus. When the generation and detection spots are separated by a known distance and plate waves (Lamb waves) are generated and detected, the method provides a measurement of the in-plane modulus and of the tension applied to the sheet. By detecting waves propagating in various directions, either by rotating the detection sensor head or multiplexing the signals provided by several detection or generation locations, the anisotropy of the in-plane modulus is determined.

Abstract: A method is disclosed for evaluating the physical properties of a sample, for example, the grain size in a polycrystalline material. An ultrasound field is generated in a local region of the sample with a non-contact source, such as a pulsed laser, such that the generated ultrasound diffuses away from said local region. After waiting until the generated ultrasound field has reached a diffusion regime, the resulting ultrasound field is measured with a non-contact detector. Parameters are adjusted in a mathematical model describing the predicted behaviour of the ultrasound field in the diffusion regime to fit the detected ultrasound field to the mathematical model. In this way, parameters dependent on the physical properties of the sample, such as the diffusion coefficient and absorption coefficient, can be derived. The grain size, for example, can be estimated from these parameters preferably by calibrating the diffusion coefficient to grain size.

Abstract: The present invention uses the generation and detection of acoustic guided waves to evaluate the condition of the insulation on electrical wiring. Low order axisymmetric and flexural acoustic modes are generated in the insulated wire and travel partially in the center conductor and partially in the outer insulation. The stiffness of the insulation and the insulation's condition affect the overall wave speed and amplitude of the guided wave. Analysis of the received signal provides information about the age or useful life of the wire insulation. In accordance with the present invention, signal transmission occurs at one location on the electrical wire to be evaluated, and detection occurs at one or more locations along the electrical wire. Additional receivers can be used to improve measurement accuracy. Either the transmission transducer or one or more receiver transducers may be angled at other than 90 degrees to the wire.

Abstract: Method for measuring vibrations in small and microscopic objects, The method comprises use of a calculation algorithm with the collection of more data sets or data images from a detector array, such that these data sets or data images are used to calculate the size of the interference modulation between the interfering light waves, while the object at the same time is vibrated at a frequency, and while a reference light or object light at the same time is phase modulated at the same frequency. Furthermore, use of a calculation algorithm based on that the said calculation of the modulation is done several times at a different vibration phase between the excitation of the object on one hand and reference modulation or the phase modulation of the object light on the other hand. Finally, the method comprises use of a calculation algorithm based on use of the results from the said calculation of the modulation to calculate amplitude values and phase values for the vibration of the surface of the object.

Abstract: The invention is directed to a system and a method for testing a physical attribute of a manufactured object. The system comprises at least one laser generator and a pulse generator that generate a plurality of Dirac-like pulses. The pulses are directed at an object, causing a sonic signal to be initiated. The sonic signal is indicative of the physical attribute of the manufactured object and it is detected by a detector and the signal. The system may also comprise a controller for controlling the width of the Dirac-like pulses and a time separation between pulses. The system may also comprise of a display for representing the detected signal or the physical attribute. The invention is also directed to a laser ultrasound testing device that generates a plurality of Dirac-like laser pulses, directs the pulses at a manufactured object, and measures a resulting ultrasound signal indicative of a physical attribute of the object.

Abstract: A system for identifying ultrasonic displacements in a material under test utilizing a time-varying output pulse of a first laser beam. The system includes a seed laser light source for providing a laser beam, a modulating assembly in the path of propagation of the laser beam for time-varying of the laser beam, at least one optical isolation assembly placed in the path of propagation of the laser beam for preventing reflected laser light feedback into the seed laser light source, and at least one laser light amplification assembly placed in the path of propagation of the laser beam for amplifying the laser beam which passes the amplified time-varying output pulse of the laser beam.

Abstract: The invention is a wafer having variable acoustic properties. The wafer may be used as a substrate over which to form an ultrasonic transducer, an IC, or may be used as a circuit board. An ultrasonic transducer formed on the wafer may include piezoelectric ceramic transducer elements or MUT elements. By controlling the acoustic impedance of the wafer upon which the integrated control circuitry for an ultrasonic transducer is formed, the acoustic impedance of the wafer can be matched to the acoustic impedance requirements of the ultrasonic transducer. Furthermore, by the addition of internal voids, the wafer reduces or eliminates the lateral propagation of acoustic energy through the wafer.

Abstract: A method and apparatus for measurement of stress in a specimen utilizing a motorized electromagnetic acoustic transducer (EMAT). Stress causes a rotation of the pure-mode polarization directions of SH-waves and a change in the phase of waves polarized along these certain directions. The method utilizes a rotating small-aperture EMAT, connected to a processor, to measure phase and amplitude data as a function of angle. The EMAT is placed on a workpiece at the location where the stress is to be measured. The acoustic birefringence B is determined from the normalized difference of these phases. From these data, an algorithm calculates values of B and &PHgr;. The workpiece is then stressed or its stress state is changed. The values are measured again at the same location. Stress is determined from the change in B and &PHgr;.

Abstract: A photoacoustic sensor that measures carbon black particles emitted in the exhaust gas of a vehicle traveling on a road or being tested on a dynamometer or engine stand. The sensor includes an acoustic waveguide and a pump mounted to an outlet of the waveguide. The pump pulls the gas through the waveguide. A critical orifice is mounted between the pump and the outlet. The critical orifice prevents noise generated by the pump from entering the waveguide. Optical windows are mounted at opposite ends of the waveguide. A modulated source of light is located adjacent one of the windows and irradiates the waveguide. A microphone is attached to the waveguide. The microphone detects an acoustic signal generated by absorption of the light by the particles in the gas. The acoustic signal is proportional to the mass concentration of particles in the gas. The microphone generates an electrical signal proportional to the acoustic signal.

Abstract: A non-destructive testing method and apparatus for determining the microstructure of ferrous metal objects, such as cast iron pipe. A sonic wave is induced into the metal object by magnetostriction. A sensor assembly captures the acoustic energy induced in the metal object and sends a signal output to signal processing electronics. The electronics amplify the signal. The amplified signal is then captured by the data acquisition system and analyzed by the data analysis system. The data analysis system may calculate the energy of the acoustic wave or calculate the time from the initial induction of the sonic wave to the Villari reversal point to determine nodularity of the metal object.

Abstract: A method and apparatus for determining stress levels of membrane masks that may be used in membrane-based lithographic techniques is presented. A piezoelectric plate (30) is used to induce vibrations into the membrane mask (35), where the frequency and amplitude of the vibrations induced in the membrane layer (50) are optically sensed. By comparing the stimulus applied to the piezoelectric plate (30) with the response sensed optically in a gain phase analyzer (80), a frequency graph (110) associated with the membrane layer (50) is constructed such that resonant frequencies are easily determined. These resonant frequencies can then be used to calculate the stress associated with the membrane layer (50).

Abstract: An ultrasonic detection method and apparatus are suited for real-time collection of three-dimensional ultrasonic data.