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Proceedings Paper

THz near-field imaging of biological tissues employing synchrotron radiation (Invited Paper)
Author(s): Ulrich Schade; Karsten Holldack; Michael C. Martin; Daniel Fried
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Paper Abstract

Terahertz scanning near-field infrared microscopy (SNIM) below 1 THz is demonstrated. The near-field technique benefits from the broadband and highly brilliant coherent synchrotron radiation (CSR) from an electron storage ring and from a detection method based on locking on to the intrinsic time structure of the synchrotron radiation. The scanning microscope utilizes conical waveguides as near-field probes with apertures smaller than the wavelength. Different cone approaches have been investigated to obtain maximum transmittance. Together with a Martin-Puplett spectrometer the set-up enables spectroscopic mapping of the transmittance of samples well below the diffraction limit. Spatial resolution down to about λ/40 at 2 wavenumbers (0.06 THz) is derived from the transmittance spectra of the near-field probes. The potential of the technique is exemplified by imaging biological samples. Strongly absorbing living leaves have been imaged in transmittance with a spatial resolution of 130 μm at about 12 wavenumbers (0.36 THz). The THz near-field images reveal distinct structural differences of leaves from different plants investigated. The technique presented also allows spectral imaging of bulky organic tissues. Human teeth samples of various thicknesses have been imaged between 2 and 20 wavenumbers (between 0.06 and 0.6 THz). Regions of enamel and dentin within tooth samples are spatially and spectrally resolved, and buried caries lesions are imaged through both the outer enamel and into the underlying dentin.

Paper Details

Date Published: 13 April 2005
PDF: 7 pages
Proc. SPIE 5725, Ultrafast Phenomena in Semiconductors and Nanostructure Materials IX, (13 April 2005); doi: 10.1117/12.590731
Show Author Affiliations
Ulrich Schade, Berliner Elektronenspeicherring-Gesellschaft fur Synchrotronstrahlung mbH (Germany)
Karsten Holldack, Berliner Elektronenspeicherring-Gesellschaft fur Synchrotronstrahlung mbH (Germany)
Michael C. Martin, Lawrence Berkeley National Lab. (United States)
Daniel Fried, Univ. of California/San Francisco (United States)


Published in SPIE Proceedings Vol. 5725:
Ultrafast Phenomena in Semiconductors and Nanostructure Materials IX
Kong-Thon Tsen; Jin-Joo Song; Hongxing Jiang, Editor(s)

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