ENDOTERA
Duration: 12 months, Start: July 2017
Academic project leader: Jacques E. Moser, Institution: Institute of chemical sciences and engineering, Group for Photochemical Dynamics, EPFL, Lausanne. Industrial project partner: Dr. Ahmad Ajdar Zadeh, Aekip SA.Project title: Development of a Scan-free Terahertz Endoscopy Instrument: Targeting Bio-Medical Applications
Development of terahertz (THz) spectroscopy and imaging techniques has created powerful probing tools for many applications in chemistry, material sciences, biology, etc. Interesting biomedical applications have been proposed for THz technology. Among them are early detection, long-term monitoring and control of cancer cells, as well as dynamic imaging of skin drug absorption. THz techniques are promising for biomedical applications; since they are rather safe and they provide images with good resolution and sensitivity. In addition, in spectroscopic mode, they allow to detect particular biochemical compounds present in the sample. Results can be monitored, in most cases, in real-time. However, some drawbacks of available THz systems, such as their high price and short radiation penetration depth in tissues have prevented so far their vast commercialization and wide use in biomedical applications.
The Photochemical Dynamics Group of EPFL has many years of experience in the development of various THz systems. In partnership with Aekip SA, founded by former researchers of EPFL, we aim at developing a compact prototype for THz endoscopy, in order to perform THz imaging and spectroscopy in vivo. We aim in particular at cancer cell detection in hollow organs and in live tissues during surgery. Main R&D effort at this stage is directed to the design of a scan-free, wide-field THz endoscopic imaging system, using a thin and flexible multimode waveguide.
The Figure shows a schematic drawing of THz endoscopic system based on multimode waveguide imaging and the transmission matrix method. The beam splitter (BS1) splits the THz beam and the transmitted beam is reflected by a two-axis scanning mirror (SM), which controls the incident angle (qx, qy)S into the waveguide. Passing through the objective lens (OL) the beam is reflected by BS2, and couples to the waveguide at input plane (IP), and subsequently propagates toward the sample. The THz beam reflected from the sample is guided back through the waveguide to the IP. The output image is then delivered through the beam splitters (BS2 and BS3) into the THz camera. The THz beam reflected by BS1 is combined with the beam from the waveguide to form an interference image at the camera. Using an off-axis digital holography algorithm, both amplitude and phase of the image are retrieved.
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