Improvement of Velocity Measurement Accuracy of Leaky Surface Acoustic Waves for Materials with Highly Attenuated Waveform of the V(z) curve by the Line-Focus-Beam Ultrasonic Material Characterization System

Abstract

Measurement accuracies of leaky surface acoustic wave (LSAW) velocities for materials with highly attenuated waveforms of VðzÞ curves obtained by the line-focus-beam ultrasonic material characterization (LFB-UMC) system are investigated. Theoretical investigations were carried out and experiments were performed for TiO 2 -SiO 2 glass (C-7972), Li 2 O-Al 2 O 3 -SiO 2 glass ceramic (Zerodur Ò ), and (111) gadolinium gallium garnet (GGG) single crystal as specimens. Waveform attenuations of VðzÞ curves for C-7972 and Zerodur Ò are greater than those for the (111) GGG single crystal. Frequency dependences of the waveform attenuations were calculated for each specimen by considering the propagation attenuation of LSAWs. The theoretical results revealed that the waveform attenuation dominantly depends upon the acoustic energy loss due to the water loading effect on the specimen surface, and that the waveform attenuation becomes smaller with decreasing frequency. Significant improvement of the measurement precision of LSAW velocities was demonstrated for each specimen using three LFB ultrasonic devices with different curvature radii R of the cylindrical acoustic lenses: R ¼ 2:0 mm at 75 MHz, R ¼ 1:5 mm at 110 MHz, and R ¼ 1:0 mm at 225 MHz; for C-7972, the precisions were improved from AE0:0053% at 225 MHz to AE0:0020% at 75 MHz.

Evaluation and selection of EUVL-grade TiO2-SiO2 ultra-low-expansion glasses using the line-focus-beam ultrasonic material characterization system

“…It is possible to obtain higher CTE resolution if the operating frequency is changed to the lower frequencies, such as 75 MHz, although it was 225 MHz in this paper. 14 …”

“…9, 10 We also investigated methods to evaluate specimens with periodic striae and to prepare appropriate standard specimens with periodic striae. 11 And, we obtained an accurate calibration line, viz., a relationship between LSAW velocities and TiO 2 concentrations, 12 improved velocity measurement accuracy to obtain higher CTE resolution, 13,14 and evaluate striae structure of TiO 2 -SiO 2 glasses. 15,16 Through these achievements, we demonstrated usefulness of the LFB-UMC system for CTE evaluation of TiO 2 -SiO 2 ultra-low-expansion glasses.…”

Introduction of measurement techniques in ultrasonic electronics: Basic principles and recent trends

“…The forms of waves and related devices have also been researched. The forms of waves include surface waves, boundary waves, 71,97,138,155,159,[182][183][184][185][186][187][188] and guided waves. 152,180,189,190) Temperature and flow measurements and their visualization have also been performed in air as examples of environmental measurement.…”

Nondestructive Determination of Elastic Constants of Thin Isotropic Plates Based on Poly(vinylidene fluoride–trifluoroethylene) Copolymer Ultrasound Focusing Transducers and Lamb Wave Measurements

“…The measurements of Lamb wave dispersion curves can be achieved by a number of different methods such as laser ultrasound, 8,9) use of air-coupled 10,11) or dry-contact transducers, 12,13) and acoustic microscopy. [14][15][16] In this work we will focus on the Vð f ; zÞ defocusing measurement method. [17][18][19][20][21] The difference between the Vð f ; zÞ defocusing measurement method and conventional acoustic microsco-py [14][15][16] using a lens line-focus-beam (LFB) ultrasound transducer is that the working frequency of conventional acoustic microscopy is usually high from a few tens of MHz to several hundred MHz.…”