摘要:
A system and method for generating a desired acoustic frequency content in a laser-generated ultrasonic wave emitted from a target in response to a laser pulse. The method includes generating a generation laser pulse using a laser source. An optimal wavelength &lgr;0 for the generation laser pulse is determined using a computer. The optimal wavelength data is determined from material-specific, empirically calculated data stored in a storage device that is accessible to the computer. An optimal laser pulse is generated by shifting the generation laser pulse to the optimal wavelength &lgr;0. The optimal laser pulse is directed to the target to generate the laser-generated ultrasonic wave with the desired frequency content.
摘要:
Ultrasonic testing techniques may involve the measurement of ultrasonic waves from the tested part. These waves may reflect from surfaces of various layers within the part. Further, these waves may reflect from faults, defects, voids, fractures, and others. As such, the measured ultrasonic wave is a complex mix of these reflections. One method for detecting flaws, defects, and others may be to express the signal in terms of a set of basis functions. These functions may be summed to produce the measured signal. Further, basis functions may be chosen such that a select set of the basis functions characterize the fault and/or defect. In one exemplary embodiment, the coefficients associated with the basis function may be non-zero when a defect is present. As such, a defect may be detected quickly and automatically.
摘要:
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.
摘要:
The invention is directed to a wave characteristic adjusting device used to compensate for a wave characteristic distortion caused by the scanning motion of a probe beam of a two-wave mixing interferometer. The invention is also directed to an apparatus and method for using the wave characteristic adjusting device in a rapid scanning laser ultrasound testing device. In a rapid scanning laser ultrasound testing device, a laser pulse is directed at periodic points along a path across the surface of a manufactured object. The laser pulse initiates an ultrasonic signal associated with the manufactured object. An interferometer may be used to measure the initiated ultrasonic signal. The interferometer scans a probe beam along a path similar to the sonic initiating laser. A pulse of the probe beam is directed at the manufactured object in the vicinity of the initiating laser pulse while continuously scanning. As a result, the probe beam pulse may exhibit a Doppler shift. This Doppler shift may cause a loss in sensitivity of the two-wave mixing interferometer. The wave characteristic adjusting device may be used to compensate for the Doppler shift, thereby improving the sensitivity of the two-wave mixing interferometer.
摘要:
The invention provides for ultrasonically measuring the porosity in a sample composite material by accessing only one side of the sample composite material and includes the steps of measuring a sample ultrasonic signal from the sample composite material, normalizing the sample ultrasonic signal relative to the surface echo of the sample composite material, and isolating a sample back-wall echo signal from the sample ultrasonic signal. A sample frequency spectrum of the sample back-wall ultrasonic signal is then determined. Next, the method and system include the steps of measuring a reference ultrasonic signal from a reference composite material, normalizing the reference ultrasonic signal relative to the surface echo of the reference composite material; and isolating a reference back-wall echo signal from the sample ultrasonic signal. A reference frequency spectrum of the reference back-wall ultrasonic signal is then determined. The invention further includes deriving the ultrasonic attenuation of the sample ultrasonic signal as the ratio of the sample frequency spectrum to the reference frequency spectrum over a predetermined frequency range. Comparing the derived ultrasonic attenuation to predetermined attenuation standards permits evaluating the porosity of the sampled composite material.
摘要:
The invention is directed to a system and method for detecting defects in a manufactured object. These defects may include flaws, delaminations, voids, fractures, fissures, or cracks, among others. The system utilizes an ultrasound measurement system, a signal analyzer and an expected result. The signal analyzer compares the signal from the measurement system to the expected result. The analysis may detect a defect or measure an attribute of the manufactured object. Further, the analysis may be displayed or represented. In addition, the expected result may be generated from a model such as a wave propagation model. One embodiment of the invention is a laser ultrasound detection system in which a laser is used to generate an ultrasonic signal. The signal analyzer compares the measured ultrasonic signal to an expected result. This expected result is generated from a wave propagation model. The analysis is then displayed on a monitor.
摘要:
The invention is directed to a laser ultrasound testing system with adaptive generation of sonic energy signals. The system may detect or test features of the manufactured object such as defects and layer properties. A laser generator initiates a sonic energy signal in a manufactured object. A measuring device measures the sonic energy signal. Then, a signal analyzer and/or a model processor determine if the signal is optimized. If the signal is not optimized, optimized operating characteristics of the laser generator are calculated. These optimized operating characteristics may include wavelength, beam dimension, temporal profile and power. Next, the laser generator initiates an improved sonic energy signal by utilizing the optimized operating characteristics. In this manner, more accurate testing and detection is achieved.
摘要:
The invention is directed to a system and method for detecting defects in a manufactured object. These defects may include flaws, delaminations, voids, fractures, fissures, or cracks, among others. The system utilizes an ultrasound measurement system, a signal analyzer and an expected result. The signal analyzer compares the signal from the measurement system to the expected result. The analysis may detect a defect or measure an attribute of the manufactured object. Further, the analysis may be displayed or represented. In addition, the expected result may be generated from a model such as a wave propagation model. One embodiment of the invention is a laser ultrasound detection system in which a laser is used to generate an ultrasonic signal. The signal analyzer compares the measured ultrasonic signal to an expected result. This expected result is generated from a wave propagation model. The analysis is then displayed on a monitor.
摘要:
A system and method for generating ultrasonic displacements on a remote target. The method of the present invention includes the steps of first using a laser to generate a beam having a first wavelength to produce ultrasonic displacements at the remote target. This laser beam will have a first wavelength which can be modulated to alter characteristics of the ultrasonic displacements. These ultrasonic displacements at the remote target can be optimized to enhance the detection optics for collecting phase modulated light from the second pulsed laser beam either reflected or scattered by the remote target; an interferometer to process the phase modulated light and generate at least one output signal, and means for processing the at least one output signal to obtain data representative of the ultrasonic surface displacements on the surface of the remote target.
摘要:
Image quality is assessed for a digital image that is a composite of tiles or other image segments, especially focus accuracy for a microscopic pathology sample. An algorithm or combination of algorithms correlated to image quality is applied to pixel data at margins where adjacent image segments overlap and thus contain the same content in separately acquired images. The margins may be edges merged to join the image segments smoothly into a composite image, and typically occur on four sides of the image segments. The two versions of the same image content at each margin are processed by the quality algorithm, producing two assessment values. A sign and difference value are compared with other image segments, including by subsets selected for the orientation of the margins on sides on the image segments. The differences are mapped to displays. Selection criteria determine segments to be re-acquired.