Terahertz Spectroscopy and Brewster Angle Reflection Imaging of Acoustic Tiles

Figure 6

Spectral content reflection images () of tile sample “A1-8” in the range of 80 GHz. Positions of the voids are highlighted by the arrows. (a) Color photograph. (b) THz reflection image. (c) THz reflection image with larger hole fully injected with water. (d) THz reflection image with both holes fully injected. Unfortunately, a computer fault interrupted scan (d) before completion. The vertical dark bands at the sides of the tiles are edge effects due to the oblique incidence angle of the THz beam, which also distorts the shapes of the hidden defects horizontally. The acquisition time for each image was approximately 10 hours, limited primarily by the electronics of the raster scanning.

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