Photonic Advances Enhance Imaging Techniques

Optical Society

Optica Foundation recipients’ work in 3-D Microparticle Imaging, Optical Coherence Tomography (OCT) and Synthetic Wavelength Holography (SWH) may lead to more efficient, cost-effective systems

  • Optica Foundation 20th Anniversary Challenge leads to developments in healthcare imaging, specifically in Differential Interference Contrast (DIC) microscopy, Optical Coherence Tomography (OCT), and Synthetic Wavelength Holography (SWH)
  • Work from researchers in Singapore, China, and the United States focuses on enhancing the clinical efficacy and efficiency of advanced modalities, as well as increasing access to these techniques by decreasing cost and system size

WASHINGTON – The Optica Foundation today issued details on the healthcare work being funded by its 20th Anniversary Challenge. This newly funded research will address the potential of Differential Interference Contrast (DIC) microscopy, accessibility and portability of Optical Coherence Tomography (OCT), and applicability of Synthetic Wavelength Holography (SWH), a method to image through light-scattering materials like human skin.

“The field of imaging has benefited greatly from advances in photonics,” said Majid Ebrahim-Zadeh, ICFO – Institut de Ciencies Fotoniques, Spain, and member of the 20th Anniversary Challenge Selection Committee. “The research being conducted by the challenge recipients strives to solve for today’s pain points in imaging, including efficiency and accessibility. We expect these efforts to lead to continued investigation and advancement in this critical field.”

Healthcare initiatives from the 20th Anniversary Challenge include the following:

Transparent Microparticle and Cancer Cell Imaging

  • Guangwei Hu, Nanyang Technological University, Singapore

Single-shot, Isotropic and Miniaturized Differential Interference Contrast (SIM-DIC) Microscopy based on computational flat-optics

Research Executive Summary

Optical microscopy offers a method of imaging tiny samples, even transparent ones, to track their movements in real-time in 3-D. To achieve that goal today, researchers deploy a bulky system, such as differential interference contrast microscopy, measuring elements in one dimension at a time due to orientation sensitivity. However, Guangwei Hu, Nanyang Technological University, Singapore, is working to change the approach.

To address shortcomings in current optical microscopy approaches, Hu’s research proposes using flat optical elements or metasurfaces to create smaller, more efficient, and more powerful systems. By leveraging silicon nanostructures as a foundation, the planned system will be set to perform multiple functionalities at one time, including the focusing phase, polarization multiplexing, and isotropic edge detection-all in 3-D- via a portable device that can potentially link up with standard consumer electronics.

“I’m trying to revolutionize existing microscopic techniques with new and advanced optical elements based on metasurfaces,” explains Hu. “It’s a new crossover, really merging microscopic imaging systems with metasurfaces.”

Hu has already conducted initial work on the fundamental limits and principals behind his approach and has developed designs to fabricate for testing. He plans to begin with a demonstration of the microscopy system, and within six months, Hu expects to operate the system on biological samples of cancer cells.

“The ultimate goal is that healthcare researchers and practitioners could have a module that they can even place on their mobile phone to image,” said Hu. “At the end of the day, the proposed single-shot, isotropic and miniaturized DIC system is portable and simple to operate, because it’s essentially just a very detailed lens.”

Portable OCT Platforms for Disease Detection

  • Xingchen Ji, Shanghai Jiao Tong University, China

Developing low-cost, portable, integrated OCT systems using low-loss silicon nitride platform

Research Executive Summary

Optical Coherence Tomography (OCT) is a non-invasive imaging modality that provides high-resolution images of tissue for more than 30 million scans each year. However, due to the complexity of system elements, prohibitive costs for purchase and maintenance, and its generous size, the product’s accessibility is limited. But new efforts from Xingchen Ji, Shanghai Jiao Tong University, China, promise to develop an alternative OCT system that is both portable and low cost.

“My proposal is about developing a portable, low-loss OCT system prototype, based on silicon photonics, and more specifically, silicon nitride,” shared Ji. “This way, all of the elements of a traditional OCT system could be covered by a single platform, a whole system rather than single parts. If this idea succeeds, we will be able to reduce both the size and cost of OCT systems by orders of magnitude.”

Ji explained that his first step is to optimize the fabrication process, and then design the light source, interferometer and spectrometer components of the system. In three months, he hopes that they will demonstrate the low-loss platform that supports the system’s design, and by six months, they will be able to acquire OCT images. At the end of a year, Ji aspires to have a working prototype.

“What we are trying to do here is make OCT widely accessible. Once we have a miniaturized system, we can reduce costs to $1,000 or below per device. I can even imagine a day when you would have one at home, and you could transfer the images to the cloud so the doctor could review them, without having to go to the hospital, office, or clinic,” Ji said.

Precise Imaging through Living Tissue with Standard Camera Technology

  • Florian Willomitzer, University of Arizona, USA

Noninvasive high-resolution imaging through living tissue with single-shot synthetic wavelength holography

Research Executive Summary

Over the last decades, the field of medical imaging has spawned several seminal inventions, including Optical Coherence Tomography (OCT), Computed Tomography (CT), ultrasound, and Magnet Resonance Imaging (MRI). Recent years have seen a growing interest in medical imaging techniques which enable a look inside the human body with high precision but are non-invasive and can be facilitated in a small form factor, i.e., possibly even operated in a hand-guided fashion. Now, work from Florian Willomitzer at the University of Arizona, USA, seeks to demonstrate an important step towards this new breed of medical imaging devices: single-shot Synthetic Wavelength Holography (SWH).

“Our previously demonstrated method of Synthetic Wavelength Holography shows great potential for a multitude of medical imaging applications, but currently still requires a temporal sequence of images to ‘see’ through scattering media like tissue. If something moves during the acquisition of this temporal image sequence, the measurement fails. This makes the current method unfeasible for real-world medical applications, as living tissue is in constant movement,” said Willomitzer. “This new work addresses this problem by introducing an approach that enables precise SWH measurements with only one single camera image. The vision is to create an efficient and cost-effective imaging system which uses standard, off-the-shelf camera technology – theoretically even mobile phone cameras.”

Willomitzer will start by building on recent research that demonstrated the success of multi-shot SWH, refining the approach to function in a single-shot environment. In six months, he intends to have developed baseline criteria for his hypothesized one-shot approach, and then will evaluate its potential for real-world medical imaging applications, i.e., the imaging of small structures, such as capillaries, lesions, tumors, etc., through scattering media, such as tissue and bone.

“The proposed technique could have profound effects on future industries that go far beyond potential applications in medical imaging. Possible examples include applications in autonomous vehicles, virtual reality, industrial inspection, and many more,” Willomitzer concluded.

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