Towards a THz imager for eye diagnosis

Sandwiched between microwaves and infrared in the electromagnetic spectrum, THz radiation (ca. 0.1 – 3 THz) holds promise for medical diagnosis, security applications (chemical fingerprinting and standoff screening) and industrial control processes [1]. The potential of THz in these realms arises from the ability of THz radiation to pass through many optically opaque materials (e.g., clothing, paper, etc.), its achievable (sub-)millimeter resolution and the fact that specific rotations, vibrations or librations of molecules and molecular aggregates occur in this frequency range. In addition, THz radiation is non-ionizing and safe, unlike X-rays. In Life Sciences applications, where specimens stay in an aqueous environment (like the human eye), THz spectroscopy and imaging meets a special challenge: 1 mm of water attenuates a THz signal by a factor of ~1000 times! To tackle this problem, THz imaging and spectroscopy should be done in reflection (reflectometry) [2] or in the low part of the THz spectrum (i.e. <0.5 THz). The health of the eye is routinely assessed from the corneal tissue water content and the corneal thickness. Current clinical instruments (pachymeters) extrapolate the corneal tissue water content from the central corneal thickness. It is expected that time-resolved THz reflectometry will be able to measure directly both corneal thickness and hydration level [3]. We expect the PhD candidate to develop the expertise required to lead an experimental research project, to train students and to interact with colleagues with different backgrounds (physics and engineering). Details of the project will be agreed with the interested candidates to tailor the research to his/her interests. The research programme will take place in an international and interdisciplinary environment, which will substantially favor collaboration opportunities 1) within the School of Physics and Astronomy, 2) within the School of Engineering, and 3) within other research institutions.