Rendering the opaque transparent: Untangling light with bespoke optical transforms to see through scattering environments

When light propagates through an opaque material, such as living tissue or a multi-mode optical fibre, it fragments and scatters multiple times. The emergent wavefront no longer forms an image because the spatial information it carries has been scrambled. Reversing this scattering offers the prospect of using visible light for high-resolution imaging of structures deep inside the human body in a safe, non-ionising way. It has recently been shown that this light scattering can be characterised and inverted. Yet arbitrary spatial mode inverters that can unscramble hundreds of light modes simultaneously to efficiently reform an image do not currently exist. The aim of this project is to understand how to design and build them.I will pioneer the use of focused lasers to write intricate nano-structures directly into glass. The key advancement will be to overcome extreme fabrication tolerances by employing a fluid design approach, whereby the design will be modified during the fabrication process. In parallel, I will develop dynamic transformers, capable of rapidly reprogrammable optical transformations. Further, I will create new computational techniques to overcome residual levels of crosstalk, and develop new ultra-fast scattering characterisation methods based on compressed sensing. This project will advance our fundamental understanding of how to control optical scattering in complex media. Key aims are to:- Understand how to design a new class of optical elements that can perform efficient spatial mode transforms on demand.- Build both passive spatial mode transformers to manipulate hundreds of modes simultaneously, and active transformers that can perform dynamically reconfigurable transformations at video-rates.- Apply this technology to unscramble light that has propagated through a moving multi-mode optical fibre in real-time, pushing towards ultra-thin micro-endoscopy, and explore an array of applications to next generation imaging systems and beyond.