| Summary: | 碩士 === 國立臺灣大學 === 物理學系 === 86 === The superconducting quantum interference device (SQUID) is the
most sensitive detector of magnetic flux known. The SQUID plays a very
important role and is promising in nondestructive evaluation (NDE) and
biomagnetism. The ability of the operation down to very low frequency
makes the SQUID detect the deep flaw of the sample without doing harm
to the surface. In the last decade, the NDE of SQUID has improved to the
order of 1mm for the spatial resolution.
Our experiment uses dc SQUID as a detector for NDE, and we tried
different measuring methods to find the magnetic flux density
distribution near the sample. The way we use to generate the magnetic
flux density around the sample is to inject electric current into the sample.
We also discuss the sensibility and the spatial resolution of our NDE
system. Further more, we can acquire some information about the
structure and defect of the sample by those results measured.
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