Research into Imaging Plant Pathogens using Lensless Holographic Microscopy Operating in Reflection Mode

两个最严重的全球性问题是气候变化和粮食安全。两者都与农业有关，因为农业是温室气体的主要产生者，而产量下降会对粮食安全产生负面影响。现代的趋势是通过实施“智能农业”技术将农业和技术结合起来；不仅提高了产量，而且提高了生产效率。锈病对作物构成重大风险，因为在大流行年份可能遭受全部损失。目前的预防措施包括杀虫剂和转基因作物。如果大量使用，前者对环境有害，而后者可能造成长期健康风险。早期的锈病检测，随后的局部农药应用提供了一种方法，只使用尽可能少的农药。目前的早期检测方法依赖于使用孢子陷阱和专门的实验室；使这个过程缓慢而复杂。该项目旨在开发和构建一个定制的显微镜系统，该系统可以在田间部署，以光学方式检测小麦锈病。成像系统将基于无透镜数字全息显微镜（DHM）。该技术可以提供传统成像技术无法提供的图像特征；功能，如定量相位成像。全息成像的工作原理是记录与物体相互作用的光和参考光束之间的干涉。利用光传播理论，可以在不使用透镜的情况下，对物体平面上的复杂场进行数字重建。近年来，由于现代图像传感器的特点是像素尺寸小，价格不断下降，无镜头DHM受到了极大的关注。无透镜DHM的大多数进步都是用于透射光成像，具有亚微米分辨率和多光谱成像等特征。该项目的新颖性将来自于将这些进步应用于反射模式下的无透镜DHM。

Two of the most severe global problems are climate change and food security. Both can be linked to agriculture since it is a large producer of greenhouse gasses, while a reduced yield can negatively impact food security. The modern trend is to merge agriculture and technology by implementing "smart farming" techniques; not only increasing yield, but also making the process more efficient.Rust diseases pose significant risks to crops since total losses can be encountered in bad pandemic years. Current preventive measures include pesticides and genetically modified crops. The former is environmentally detrimental if used in large quantities while the latter could pose long-term health risks. Early rust detection followed by localized pesticide application provides a way to only use as little pesticides as possible. Current early detection methods rely on using spore traps alongside specialized laboratories; making the process slow and complex.This project aims to develop and build a bespoke microscopy system that can be deployed in the field to detect wheat rusts optically. The imaging system would be based on lensless digital holographic microscopy (DHM). This technique can provide image features that are not possible with conventional imaging techniques; features such as quantitative phase imaging. Holographic imaging works by recording the interference between the light that interacts with the object and a reference beam. By using the theory of light propagation, the complex field at the object plane can be digitally reconstructed, without the use of lenses.Lensless DHM has received significant attention in recent years since modern image sensors feature small pixel sizes at ever-decreasing prices. Most advancements in lensless DHM have been for transmitted light imaging, with features such as sub-micron resolution and multispectral imaging being demonstrated. The novelty of this project would come from adapting these advancements to lensless DHM operating in reflection mode.