CEPS CDT PhD Research Project
Photonic Imaging: Shining light on vision robbing diseases


The eyes are the cameras of our body, detecting and processing images of the world around us. Just like the high-tech cameras in our mobile devices, our eyes have lenses (cornea) and sensors (retina), and even do some low-level processing before transmitting data to the main processor (brain). But when diseases affect vision, the unique optical properties of the eye can be exploited to enable photonics-based imaging for diagnosis, and also for laser-based treatments. Optical coherence tomography (OCT) is a commonly used medical imaging technique for diagnostic imaging of eyes. OCT is a rapidly evolving field, with significant opportunities for advanced system research and development. Exciting new research on OCT is concentrated on high-resolution and real-time imaging of the light-sensitive ‘photoreceptor’ in the retina at the back of the eye.

Objectives:

The overarching goals of this research are to innovate photonics and electronics systems for optical imaging. The main application area is to image the eye, and the design specifications will be developed in collaboration with ophthalmologists (eye doctors). The technical objectives are:

  1. To develop a real-time volumetric (cross-section and sub-surface) imaging system (hardware and software) using optical coherence tomography (OCT) that will be used to guide surgical treatments
  2. To correct image distortions and to provide sharp and high-resolution structural images
  3. To extract functional information of the sample in addition to the structure
  4. To integrate the acquisition system with a heads-up augmented reality display

Methods:

The focus of the work is heavily experimental and laboratory based, creating the next generation of OCT systems by combining novel light sources tunable lasers, pulsed lasers, superluminescent light emitting diodes, etc and optics mirrors, lenses, fibre optics, non-linear crystals with sensitive detectors scientific CMOS, avalanche photodiodes, photo-multiplier tubes, etc and signal processing. Applicants should enjoy: building systems from physical components, working with basic electronics and troubleshooting for sources of electrical noise, and basic programming to control data acquisition (ADC) and actuators (scanning mirrors and motorized stages).

Image distortions will be corrected by controlling the wavefront of the incident light using the methods of Adaptive Optics (AO), which were developed for astronomical imaging though the turbulent atmosphere using ground-based telescopes. This project will use components such as continuous membrane deformable mirrors, MEMS deformable mirrors, and liquid crystal spatial light modulators (SLM), and digital micromirror displays (DMD) to shape the optical wavefront towards the physical (diffraction) limited resolution.

OCT provides structural images that resemble more the familiar ultrasound medical images, but at a micro-scale. Signal processing methods such as Fourier Transform, interpolation, phase retrieval, will be performed on high performance CPUs and consumer grade GPUs to enable real-time image acquisition and display.

Novelty:

Engineering innovations in AO and OCT are required to achieve the research project goals. The clinical need for longer image depth and wider field-of-view while also increasing the volume acquisition speed is a driving force behind this research. Novel OCT system approaches that overcome the limitations of current technology are needed, exploring new light sources, detectors, and signal processing methods. This research has significant potential for innovations using Deep Learning / Artificial Intelligence integrated with the OCT signal acquisition and image reconstruction methodology.

Research on high-speed OCT acquisition combined with real-time image processing and analysis also has significant potential for applications to sensor-less adaptive optics (SAO) for high resolution imaging with cellular, and even sub-cellular, detail. SAO OCT is a rapidly emerging area of research for image-guided aberration correction for applications where conventional wavefront sensing approaches do not perform well. Potential contributions in this area includes research on robust and rapid methods for SAO, novel optical designs and experimentation with adaptive elements, and post-processing of the complex OCT interferometric data for digital aberration correction.

The research in this project is highly novel, with opportunities for multiple publications in Optica (formerly OSA) and IEEE journals. Our lab regularly presents at major international conferences, such as SPIE Photonics West (annual; San Francisco, USA), SPIE/Optica European Conference on Biomedical Optics (bi-annual; Munich, Germany), and IEEE International Photonics Conference (annual; Vancouver, Canada in 2022).

Learn more about our research on our research on AO, OCT, and AI with links to some recent publications.


Overseas Research Opportunities:

Prof. Sarunic is highly collaborative with other researchers in Europe, North America, Australia, and China. Students accepted to this PhD project will have the opportunity to visit other research laboratories to expand their knowledge and experience, while progressing in their research. As an example, students may be interested in visiting a collaborating research laboratory in Vancouver, Canada at the University of British Columbia for up to three months through the UK-Canada Globalink Doctoral Exchange.