Abstract: Imaging systems, as well as human vision systems, have limited capability for separation of spatial features and this information can also be extracted only from depth limited range. The reasons for the resolution and depth of focus limitations are related to the effect of diffraction i.e. the finite dimensions of the imaging optics as well as the geometry of the sensor. In this talk, I will present novel photonic approaches and means to exceed the above-mentioned resolution and depth of focus limitations and show how those concepts can be adapted to microendoscopy as well as to microscopy related configurations as well as embedded into the ophthalmic device while aiming to correct visual deficiencies. In the case of micro-endoscopy, I will show how the projection of high-resolution wavelength-dependent or time-dependent random codes can enhance the resolution of the collected light. That concept of wavelength and time multiplexing super-resolved imaging will also be demonstrated for imaging through biological scattering medium such as biological tissues and liquids as blood. The projected wavelength and time-dependent high-resolution encoding patterns are sent via laser-based illumination fiber while the collected light is collected via ultra-thin multi-core imaging fiber-based endoscope. Then, in the case of microscopy, I will present how the resolution limit can go below sub-wavelength bound towards nanoscopic imaging while using label-free configurations involving time multiplexing (time-dependent light collection) based upon label-free non-static nano-particles either moving in uncontrolled Brownian motion or being manipulated with light. The presented realizations either use metallic nanoparticles or silicon coated nanoparticles. The last part of the talk will be related to extending the depth of focus of imaging systems in an all-optical manner while introducing the “interference” effect based on the extended depth of focal imaging (rather than diffraction and refraction based). The proposed extended depth of focus approaches will be implemented in ophthalmic usage on top of conventional spectacles, contact lenses, and intraocular lenses while aiming to simultaneously correct various visual refractive errors, such as myopia, hyperopia, presbyopia, regular/irregular astigmatism, as well as their combinations. I will also mention how this interference-based extended depth of focus approach can be combined with nanoparticles and laser-based treatment of the surface of the cornea.
Biography: Prof. Zeev Zalevsky completed his PhD studies in Electrical Engineering at Tel Aviv University in 1996 and joined Bar-Ilan University’s Alexander Kofkin Faculty of Engineering in 2003, as a senior lecturer and a researcher, after a productive period in the startup industry. He now serves as the BIU Dean of Engineering, a position he has held since 2019. Prof. Zalevsky’s field of research is electro-optics, and specifically, imaging and super resolution, biomedical sensing and nanophotonics. Prof. Zalevsky has published more than 1,000 articles, book chapters and books in his field of specialization, as well as some 100 patents. He is a fellow of leading professional associations in the field and is the recipient of many national and international awards for his work. A number of the technologies developed in his lab were commercialized through BIRAD, the Bar-Ilan Research and Development Company, and have become leading Israeli start-ups.
https://www.eng.biu.ac.il/zalevsz/