Sub-terahertz imaging of defects in building blocks

Yutaka Oyama, Li Zhen, Tadao Tanabe, Munehito Kagaya

Research output: Contribution to journalArticlepeer-review

91 Citations (Scopus)


A compact sub-terahertz (THz) imaging system with a 0.2 THz-band GaAs TUNNETT diode oscillator and its application for non-destructive and harmless inspections of timbers, concrete and ceramic tiles are shown. Sub-THz transmission characteristics of various kinds of woods were investigated. It is shown that wood and concrete show a high transmittance in this frequency range, and that the measured absorption coefficients correlate well with the densities of woods. Then, the invisible grains, knots and diffused water inside the timbers were investigated by sub-THz transmission imaging. It is also shown that the sub-THz wave is a very efficient tool for defect recognition in concrete. Invisible cracks, diffused water and the quality of adhesion of tiles were investigated. It is concluded that the sub-THz wave has shown a high sensitivity in detecting these defects in building blocks.

Original languageEnglish
Pages (from-to)28-33
Number of pages6
JournalNDT and E International
Issue number1
Publication statusPublished - 2009 Jan
Externally publishedYes


  • Defects
  • Imaging
  • Material characterization
  • Non-contact
  • THz

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanical Engineering


Dive into the research topics of 'Sub-terahertz imaging of defects in building blocks'. Together they form a unique fingerprint.

Cite this