In the field of ultrasonic imaging technology, the problem of geometric distortion is often encountered, especially in the ultrasonic near-field. In this study, a new approach is proposed to compensate for geometric distortion in the synthetic aperture ultrasonic imaging system. This approach is based on the synthetic aperture ultrasonic holographic B-scan (UHB) imaging system, which is a combi...

An acousto-optical reconstruction method for acoustic signals using multidirectional light diffraction by finite amplitude ultrasonic pulses is presented. When crossing the ultrasonic field, the far field diffracted laser light intensity of an incident convergent lightbeam becomes modulated in time. It is found that for special conditions, concerning direction of observation, ultrasonic frequen...

Synthetic aperture focusing technique (SAFT) has been used in non-destructive testing mainly in its simplest form that mimics acoustic lenses used for focusing ultrasonic beams at a point of a solid object or structure. This paper presents a review of SAFT algorithms applied for post-processing of ultrasonic data acquired in non-destructive inspection of metals. The performance of SAFT in terms...

High contrast and resolution in phased array ultrasonic images are of importance for accurate evaluation. The spread of the ultrasonic beam is one cause of the images being unsharp. One technique for reducing the influence of the beam spread, and thereby improving the image quality, is by deconvolving the data with the point spread function of the ultrasonic beam. By assuming that the material ...

The accuracy of the time delay estimation using the direct correlation technique has been theoretically calculated. The random errors of the time delay estimation in digital ultrasonic measurement systems have been studied. The techniques for the time-offlight (ToF) estimation have been discussed. The theoretical equations for analog and discrete case are presented. Numerical simulation has bee...

The subsurface defect in the wheel tread caused from Rolling Stock Fatigue (RCF) has become more danger in high speed railway. The conventional UT and phased array UT have deficiency to find the subsurface defect from the tread surface because of limitation of ultrasonic near field. In this paper, the subsurface defect is studied by simulation and experimental results with ultrasonic technique....

A novel frequency-swept ultrasound-modulated optical tomography technique was developed to image scattering media. A frequency-swept ultrasonic wave was used to modulate the laser light passing through a scattering medium. The modulated light was received by an optical detector and was heterodyned with a reference frequency sweep. The heterodyned signal was recorded in the time domain and was t...

Vibrothermogrphy is a promising technique that uses ultrasonic elastic waves to locally stimulate defects on solids specimens and is typically applied in the aerospace and automotive industries. This technique allows for defect selective imaging using thermal waves that are generated by ultrasound waves. The mechanism involved is frictional heating or hysteresis that turns a dynamically loaded ...

Measurement system analysis (MSA) technique is an important method which is used to analyze statistical discreteness and measurement capability of a measurement system, and also one of quality improvement techniques. The paper describes analysis principle and methods of repeatability and reproducibility (R&R) in MSA, introduces MSA techniques into the field of non-destructive testing (NDT). Bas...