Evanescent-field illumination for Terahertz biological imaging

太赫兹（THz）辐射是波长在300到100微米之间的辐射。它具有成像的前景，因为它是非电离的（不像X射线），可以穿透许多光学不透明的介质。自由空间THz成像的限制是与光学成像相比分辨率差。用于提高分辨率的工业标准技术是近场光栅扫描，其将所谓的衍射极限以下的分辨率提高到几十微米。然而，这种改进是以时间为代价的。这个博士研究计划将着眼于渐逝场照明技术（通过周期性结构中的全内反射和表面模式），沿着与最先进的太赫兹相机，以实现提高空间分辨率，而无需近场光栅扫描。使用商业全光纤耦合太赫兹时域光谱仪和连续波雪崩二极管源沿着太赫兹相机，博士生将设计，建模和实现高分辨率太赫兹显微镜。显微镜的成像能力将使用生物样本进行测试。

Terahertz (THz) radiation is radiation with a wavelength between 300 and 100 micrometres. It holds promise for imaging since it is nonionizing (unlike X-rays) and can penetrate through many optically opaque media. A limitation of free-space THz imaging is poor resolution compared to optical imaging. The industry standard technique for improving resolution is near-field raster-scanning which improves the resolution below the so-called diffraction limit to a few tens of micrometres. However, this improvement comes at the expense of time. This PhD research programme will look at evanescent-field illumination techniques (via total internal reflection and surface modes in periodic structures) along with state-of-the-art THz cameras to achieve an improved spatial resolution without the need for near-field raster scanning. Using a commercial all fibre-coupled Terahertz time-domain spectrometer and CW IMPATT diode sources along with a THz camera, the PhD student will design, model and implement a high-resolution THz microscope. The imaging capabilities of the microscope will be tested using biological samples.