Ptychographic lensless coherent endomicroscopy through a flexible fiber bundle

Conventional fiber-bundle-based endoscopes allow minimally invasive imaging through flexible multi-core fiber (MCF) bundles by placing a miniature lens at the distal tip and using each core as an imaging pixel. In recent years, lensless imaging through MCFs was made possible by correcting the core-to-core phase distortions pre-measured in a calibration procedure. However, temporally varying wavefront distortions, for instance, due to dynamic fiber bending, pose a challenge for such approaches. Here, we demonstrate a coherent lensless imaging technique based on intensity-only measurements insensitive to core-to-core phase distortions. We leverage a ptychographic reconstruction algorithm to retrieve the phase and amplitude profiles of reflective objects placed at a distance from the fiber tip, using as input a set of diffracted intensity patterns reflected from the object when the illumination is scanned over the MCF cores. Our approach thus utilizes an acquisition process equivalent to confocal microendoscopy, only replacing the single detector with a camera

Model eye imaging by closed-loop accumulation of single scattering (CLASS) microscopy

‘Closed-loop accumulation of single scattering (CLASS)’ microscopy provides novel solutions to the problems of light scattering and aberration in optical imaging, providing increased imaging depth while maintaining diffraction limited resolution. This method has a great potential to increase imaging depth and resolution of current eye imaging. In this presentation, the strength and weakness of the CLASS microscopy over the current adaptive optical microscopy will be discussed. Important factors to apply CLASS microscopy to eye imaging and the possibility to imaging retina in turbid condition will be discussed by using model eye

Lineshape measurement of an extreme-weak amplitude-fluctuating light source by the photon-counting-based second-order correlation spectroscopy

We demonstrate lineshape measurement of an extreme-weak amplitude fluctuating light source by using the photon-counting-based second-order correlation spectroscopy combined with the heterodyne technique. The amplitude fluctuation of a finite bandwidth introduces a low-lying spectral structure in the lineshape and thus its effect can be isolated from that of the phase fluctuation. Our technique provides extreme sensitivity suited for single-atom-level applications.Comment: 3 pages, 3 figure