We have developed a method of terahertz (THz) solid immersion (SI) microscopy for continuous-wave reflection-mode imaging of soft biological tissues with a sub-wavelength spatial resolution. In order to achieve strong reduction in the dimensions of the THz beam caustic, an electromagnetic wave is focused into the evanescent field volume behind a medium with a high refractive index. We have experimentally demonstrated a 0.15λ-resolution of the proposed imaging modality at λ = 500 μm, which is beyond the Abbe diffraction limit and represents a considerable improvement over the previously-reported arrangements of SI imaging setups. The proposed technique does not involve any sub-wavelength near-field probes and diaphragms, thus, avoiding the THz beam attenuation due to such elements. We have applied the developed method for THz imaging of various soft tissues: a plant leaf blade, cell spheroids, and tissues of the breast ex vivo. Our THz images clearly reveal sub-wavelength features in tissues, therefore, promising applications of THz SI microscopy in biology and medicine.
Reflection-mode continuous-wave 0.15λ-resolution terahertz solid immersion microscopy of soft biological tissues
N. V. Chernomyrdin, A. S. Kucheryavenko, G. S. Kolontaeva, G. M. Katyba, I. N. Dolganova, P. A. Karalkin, D. S. Ponomarev, V. N. Kurlov, I. V. Reshetov, M. Skorobogatiy, V. V. Tuchin, K. I. Zaytsev; Reflection-mode continuous-wave 0.15λ-resolution terahertz solid immersion microscopy of soft biological tissues. Appl. Phys. Lett. 10 September 2018; 113 (11): 111102. https://doi.org/10.1063/1.5045480
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