All-Optical Near-Infrared Imaging via Semiconductor Nanocrystals

该项目将开发超紧凑、透明和多色的近红外(NIR)光成像新技术。人眼只能看到我们周围0.0035的电磁频谱(可见光)。在所有不可见光谱中，近红外光谱因其广泛的应用而特别令人感兴趣，例如在医疗诊断、食品质量控制、自动驾驶汽车和夜视方面。在传统的近红外成像技术中，近红外光被转换为电子，生成的图像被投射到显示器上，在显示器上，电子被转换为光，以便肉眼观看。因此，转换后的图像是单色的。此外，这种显示器阻碍了可见光的感知，因此扰乱了正常的视觉。此外，这种相机要么只能在短波长波段工作(例如，转换到1800 nm的Ge或InGaAs)，要么需要冷却(例如，工作在-200℃的InAs或InSb探测器)。此外，近红外相机必须体积庞大，才能容纳光/电子转换的所有组件。当今技术中使用的探测器意味着上述限制无法避免。该项目将开发一种全光学的近红外成像新技术，即不再需要光和电信号相互转换。这项技术将使用嵌入在一层薄而透明的层中的工程纳米晶体，捕捉红外光并在可见光范围内重新发射。这种方法将提供新的功能，其结果是：1.超紧凑；2.由看不见的物体形成彩色图像；在可见光和近红外范围都是透明的；这种革命性的技术将作为一种透明而灵活的薄层提供，它可以将任何玻璃表面(如护目镜和窗户)升级为近红外成像设备，从而能够同时在可见光和红外频率下观看。因此，目前肉眼看不到的信息将变得可见--水果的成熟度和物种健康。这项技术还将使我们能够在黑暗中看到看不见的物体。想象一下，在一个不需要夜间照明的世界里，没有光污染，温室气体大量减少。为了开发这项技术，将设计和制造特定的纳米晶体，将光的颜色从近红外转换为可见光。这些纳米晶体通常比人的头发小几百倍，是透明的，也就是说不会阻碍正常的视力。申请人最近发明了在透明表面(例如玻璃)上制造和验证高质量纳米晶体的技术。为了增强这些纳米晶体捕捉超弱近红外光的能力，将在近红外中混入额外的激光(也是不可见的)，以产生可见范围内的视觉强度。此外，同一阵列中的各种工程纳米晶体将被使用，这些纳米晶体能够将不同的近红外频率转换为不同的可见光频率。这将允许从近红外物体生成彩色图像。最后，额外的激光束和纳米晶体将被嵌入到透明、薄和灵活的聚合物铸件中，该铸件可以容纳在任何非平坦的表面(例如挡风玻璃和护目镜)上，并能够在近红外范围内观看，而不需要使用笨重的相机。工业样机将与Flexotronix合作完成，工业性能评估和环境测试将分别与QinetiQ和Horiba Mira合作完成。

This project will develop new technology for Near Infrared (NIR) light imaging that is ultra-compact, transparent, and multi-colour. Human eyes only see 0.0035% (visible light) of the electromagnetic spectrum around us. Among all invisible spectra, the NIR range is of particular interest because of its broad application, for example for medical diagnosis, food quality control, autonomous vehicles, and night-vision. In conventional NIR-imaging technology, the NIR light gets converted to electrons and the resultant image is projected onto a display, where electrons get converted to light again to be viewed by the eye. Therefore, the converted images are monochrome. Moreover, this display blocks the perception of visible light, therefore disrupting normal vision. Also, such cameras are either only operational in a short wavelength band (e.g. Ge or InGaAs, converting up to 1800nm) or require cooling (e.g. InAs or InSb detectors operating at -200 C). Moreover, NIR cameras must be bulky to accommodate all components for light/electron conversions.The detectors used in today's technology mean that the aforementioned limitations cannot be avoided. This project will develop a new technology for NIR-imaging that is all-optical, i.e. no longer requires optical and electric signals to be converted to each other. This technology will employ engineered nanocrystals, embedded within a thin and transparent layer, that capture the infrared light and re-emit it in the visible range. This approach will offer new functionalities as a result of:i. being ultra-compact;ii. forming colour images from invisible objects;iii. being transparent in both visible and NIR ranges;iv. capturing the visual information in the range of 400-4000nm, that is 10 times wider than the visible spectrum.Such a revolutionary technology will be provided as a transparent thin and flexible layer that can upgrade any glass surface e.g. goggles and windows, to an NIR-imaging device, enabling a view over both visible and infrared frequencies concurrently. Therefore, information that is currently invisible to the naked eye will become visible - the ripeness of fruits and species health. This technology will also enable us to see invisible objects in the dark. Imagine no light pollution and a massive reduction in greenhouse gases associated with a world where the lighting was not required to see at night.To develop this technology, specific nanocrystals to convert the colour of the light from NIR to visible will be designed and engineered. These nanocrystals, which are often a few hundred times smaller than a human hair, are transparent, i.e. do not block normal vision. The technique to fabricate and verify high-quality nanocrystals on a transparent surface (e.g. glass) has recently been invented by the applicant. In order to enhance the capability of these nanocrystals for capturing ultra-weak NIR light, the NIR will be mixed with an extra laser beam (also invisible) to generate a visual intensity in the visible range. Alongside this, various engineered nanocrystals within the same array, which enable conversion of different NIR frequencies into different visible frequencies will be employed. This will allow the generation of colour images from NIR objects. Finally, the extra laser beam and the nanocrystals will be embedded within a transparent, thin and flexible polymer cast that can be accommodated on any non-flat surface (for example windshields and goggles) and enable vision over the NIR range, without using bulky cameras. Industrial prototyping will be done in collaboration with Flexotronix, and industrial performance evaluations and environmental tests will be done in collaboration with QinetiQ, and Horiba Mira, respectively.