Location

Snowmass Village, CO

Start Date

1-1-1995 12:00 AM

Description

Through the last years in the acoustical imaging area significant progress has been obtained. One of the important factors of ultrasonic visualization system performance is the primary transducer spatial resolution, its sensibility and signal-to-noise ratio. A common way to improve spatial resolution is to increase nominal frequency of a probe. But the high damping rate of acoustical waves in most metals at frequencies 2.5–5 MHz give here a strong limitation. One of the efficient methods to improve probe’s sensibility and lateral resolution is a focusing. In practice when one has to solve the problem of the focusing for obliquely impinging beams upon an interface between two media, it is very important to estimate the influence of the sound waves refraction on the acoustical field pattern. The present study concerns the focusing beam geometry evaluation using plane waves and Fresnel integral approach. We have calculated, for shear wave probes, focal spot patterns in metals with shear wave velocity about 3000–3300 m/s i.e. for steels, aluminum and its alloys, first medium being polymer with longitudinal wave velocities 2400–3500 m/s and different damping level, which gave the possibility to determine allowed variations of aforementioned factors for a good focusing. One simple way to decrease the aberrations and improve the focusing for the shear waves transducers is proposed.

Book Title

Review of Progress in Quantitative Nondestructive Evaluation

Volume

14A

Chapter

Chapter 4: Transducers, Sensors, and Process Control

Section

Ultrasonic Transducer Fields and Ray Tracing

Pages

1083-1089

DOI

10.1007/978-1-4615-1987-4_137

Language

en

File Format

application/pdf

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Jan 1st, 12:00 AM

Investigation of Focusted Ultrasonic Beam Refraction on the Plane Interface Between Two Media

Snowmass Village, CO

Through the last years in the acoustical imaging area significant progress has been obtained. One of the important factors of ultrasonic visualization system performance is the primary transducer spatial resolution, its sensibility and signal-to-noise ratio. A common way to improve spatial resolution is to increase nominal frequency of a probe. But the high damping rate of acoustical waves in most metals at frequencies 2.5–5 MHz give here a strong limitation. One of the efficient methods to improve probe’s sensibility and lateral resolution is a focusing. In practice when one has to solve the problem of the focusing for obliquely impinging beams upon an interface between two media, it is very important to estimate the influence of the sound waves refraction on the acoustical field pattern. The present study concerns the focusing beam geometry evaluation using plane waves and Fresnel integral approach. We have calculated, for shear wave probes, focal spot patterns in metals with shear wave velocity about 3000–3300 m/s i.e. for steels, aluminum and its alloys, first medium being polymer with longitudinal wave velocities 2400–3500 m/s and different damping level, which gave the possibility to determine allowed variations of aforementioned factors for a good focusing. One simple way to decrease the aberrations and improve the focusing for the shear waves transducers is proposed.