Data Acquisition in Tomographic Acoustic Microscopy

Abstract

The principles of tomography can be used to enhance the capability of acoustic microscopy. An approach for employing these principles, called scanning tomographc acoustic microscopy (STAM), applies t e c b q u e s of tomographic reconstruction in order t o process data acquired by usmg a modified scanmng laser acoustic microscope (SLAM). Thls paper contains a study of signal detection performed in a conventional SLAM system. The paper describes mecharucal and electronic modlfications of SLAM in order to facihtate proper data acquisition for STAM. The question of rotatmg either the transducer or the specimen to provide tomographic projections is addressed. I t is shown that in principle both rotations will work but rotatlng the specimen is mechanically the more feasible of the two. INTRODUCI'IONAcoustic microscopy is an important branch of nondestructive evaluation whch provides hgh-resolution micrographs of specimens to be evaluated. Acoustic energy can often give a view of a cross section not available with X-rays or other types of ra&ation. The principles of tomography can be used to enhance the capability of acoustic microscopy. A techmque for applying these principles, called scanning tomographc acoustic microscopy (STAM), utilizes digital signal processing of information obtained by employing a mo&fied scanning laser acoustic microscope (SLAM). The t e c h q u e is holographc in character [I] and is reminiscent of conventional X-ray focal-plane tomography. It is most

Humanizing Education for Immigrant & Refugee Youth

“…Research demonstrates the power of a diverse educational staff. Students need to see themselves and their community represented among the teaching staff (Gers Gershenson;Hansen;Lindsay, 2021;Cherng;Halpin, 2016). Bilingual educators play crucial roles as instructors, interpreters, curriculum developers, and advisors.…”

Educação Humanizadora para Jovens Imigrantes e Refugiados

“…Pesquisas demonstram o poder de uma equipe educacional diversificada. Os estudantes precisam ver a si mesmos e sua comunidade representados entre o corpo docente (Gershenson;H ansen;Lindsay, 2021;Cherng;Halpi n, 2016). Educadores bilíngues desempenham papéis cruciais como instrutores, intérpretes, desenvolvedores de currículos e orientadores.…”