THEIA: fast super-resolution TeraHErtz mIcroscopy for nAtural sciences

太赫兹显微镜位于物理学和电气工程之间的界面，它为生物学，化学，物理学和工程学的前沿研究和开发提供了平台。通过探测与红外辐射和光相比根本不同的生物分子结构和功能动力学信息，THz辐射有望彻底改变生命科学的光谱学和成像。此外，太赫兹辐射具有非电离性的优点，对极性物质（如水）非常敏感，与危险的X射线或光学成像技术相比，可以提供无标记的皮肤病诊断和更好的软组织图像对比度。因此，THz技术的广泛采用，更不用说THz显微镜了，已经落后于微波，红外和光学。另一个阻碍太赫兹显微镜发展的障碍是，它无法在近实时操作的情况下实现低于衍射极限的分辨率，这是它的光学同行几十年前用荧光团实现的一个特征。这种超分辨率和快速采集时间特征对于生命科学尤其重要，细胞）具有微米尺寸，并且通常在其生物环境中连续运动。本研究计划中提出的变革性太赫兹显微镜将明确解决这一问题，并将通过结合来自完全不同领域的两种技术来实现在太赫兹频率下从未见过的快速无标记超分辨率成像：倏逝波照明（用于光学显微镜和光纤传感器）和合成孔径收集（用于星载遥感）。为了成功实现太赫兹显微镜，该项目将不得不：（i）设计和制造基于超颖表面的新的高性能光学器件，因为传统的透镜在太赫兹频率下是有损耗的，而且体积庞大。(ii)开发专用于显微系统的有效信号分析和处理算法，以使人们能够研究生物样品的时间演变的速率生成具有增强分辨率的图像。 (iii)该项目将设计系统、整合硬件（太赫兹光源、高性能光学器件和太赫兹相机）和软件（控制和图像重建算法），并校准显微镜，以创建一个交钥匙系统。该项目还将（iv）将0.3太赫兹显微镜与其他频率和成像模式进行基准测试，以量化其对生命科学显微镜领域的附加值。这些信息对于与生命科学界的接触至关重要，因为太赫兹技术在工程和物理科学界之外基本上尚未开发。

THz microscopy lies at the interface between physics and electrical engineering, and it provides a platform for cutting-edge research and development in biology, chemistry, physics and engineering. By probing fundamentally different information about biomolecular structure and functional dynamics compared to infrared radiation and light, THz radiation promises to revolutionize spectroscopy and imaging for the life sciences. In addition, THz radiation has the advantage of being non-ionizing and very sensitive to polar substances, such as water, and provides label-free skin disease diagnosis and better image contrast for soft tissues than hazardous X-rays or optical imaging techniques.Until recently though, THz sources and detectors were very cumbersome. Hence, the widespread adoption of THz technology, let alone THz microscopy, has lagged behind microwaves, infrared and optics. Another hurdle that has held THz microscopy back is its failure to accomplish resolution below the diffraction limit with near-real-time operation, which is a feature that its optical counterpart achieved few decades ago with fluorophores. Such super-resolution and fast acquisition time features are especially critical for the life sciences whose specimens (e.g., cells) have micrometer-dimensions and are typically in continuous motion in their biological environment. The transformative THz microscope proposed in this research programme will explicitly address this problem and will achieve fast label-free super-resolution imaging not seen before at THz frequencies by combining two techniques from completely different realms: evanescent-wave illumination (used in optical microscopy and in optical fibre sensors) and synthetic-aperture collection (used in spaceborne remote sensing). To succeed in the implementation of the THz microscope, the project will have to: (i) design and fabricate new high-performance optics based on metasurfaces since conventional lenses are lossy at THz frequencies, as well as being bulky. (ii) develop efficient signal analysis and processing algorithms specific to the microscopy system to generate images with enhanced resolution at a rate that enables one to study the temporal evolution of biological samples. (iii) design the system, integrate the hardware (THz source, high-performance optics, and THz camera) and software (control and image reconstruction algorithm) and calibrate the microscope to create a turn-key system.The project will also (iv) benchmark the 0.3 THz microscope against other frequencies and imaging modalities to quantify its added value to the field of life sciences microscopy. This information will be crucial to engage with the life sciences community since THz technology is largely untapped outside the engineering and physical science communities.