Image processing techniques for NDE SQUID systems

Author

Barbosa, C.H. ; Bruno, A.C. ; Scavarda, L.F. ; Lima, E.A. ; Costa Ribeiro, P. ; Kelber, C.

Author_Institution

Dept. de Fisic, Univ. Catolica do Rio de Janeiro, Brazil

Volume

5

Issue

2

fYear

1995

fDate

6/1/1995 12:00:00 AM

Firstpage

2478

Lastpage

2481

Abstract

Image processing techniques were used to enhance magnetic data generated by SQUID nondestructive evaluation of conducting plates. The process consists of low-pass filtering the acquired data with a FIR filter with order depending on the standoff distance and background noise. In addition a high-pass FIR filter is used to enhance the magnetic field disturbance due to the flaw. The technique was tested on magnetic field data generated through a dc current applied to flawed aluminum test samples, and detected by using an RF-SQUID system. It was observed that when the standoff distance exceeds 5 times the size of the flaw, image inspection is difficult. Applying the enhancement algorithm, magnetic field disturbances could be visualized at distances 10 times the size of the flaw.<>

Keywords

FIR filters; SQUID magnetometers; SQUIDs; flaw detection; low-pass filters; magnetic field measurement; magnetometers; FIR filter; NDE; SQUID systems; background noise; conducting plates; flawed test samples; image inspection; image processing techniques; low-pass filtering; magnetic data; magnetic field disturbance; magnetometers; nondestructive evaluation; standoff distance; Background noise; DC generators; Filtering; Finite impulse response filter; Image processing; Low pass filters; Magnetic fields; Magnetic separation; SQUIDs; System testing;

fLanguage

English

Journal_Title

Applied Superconductivity, IEEE Transactions on

Publisher

ieee

ISSN

1051-8223

Type

jour

DOI

10.1109/77.403093

Filename

403093