Scanning-free imaging through a single fiber by random spatio-spectral encoding

Abstract

We present an approach for two-dimensional (2D) imaging through a single single-mode or multimode fiber without the need for scanners. A random scattering medium placed next to the distal end of the fiber is used to encode the collected light from every imaged pixel with a different random spectral signature. 2D objects illuminated by a white-light source are then imaged from a single measured spectrum at the fiber's proximal end. The technique is insensitive to fiber bending, an advantage for endoscopic applications.

Deep brain fluorescence imaging with minimally invasive ultra-thin optical fibers

“…Although the EF in our imaging system may not be as high as one that can be obtained with LC-SLM based approaches, we demonstrate it is sufficient to acquire images which allow identification of fine features at the neuronal scale. A key improvement over previously proposed methods [22][23][24][25] , which is required for live imaging, is the ability to rapidly scan a large field of view, while maintaining sufficient spatial resolution to resolve cellular details and a high enough sensitivity to precisely measure small fluorescence fluctuations. The ability to rapidly switch between two light sources and to form structured light patterns may be useful to manipulate specific cells within the field of view using optogenetics.…”

Widefield lensless imaging through a fiber bundle via speckle correlations

“…Similar to the recently introduced computational endoscopic and spectroscopic techniques [3,4,27], the object image is computationally extracted from a relatively low contrast camera image. The raw image contrast is the result of the incoherent sum of shifted speckle patterns, and is inversely related to the square-root of the number of bright resolution cells on the object [20].…”

“…They enable imaging at depths where scattering prevents noninvasive microscopic investigation. An ideal microendoscopic probe should be flexible, allow real-time diffraction-limited imaging at various working distances from its facet, while maintaining a minimal cross-sectional footprint [1,2].Single-mode fibers (SMF) can be used as small diameter light-guides for endoscopic imaging, but in order to obtain two-dimensional (2D) images a mechanical scanning head [1,2] or a spectral disperser [3,4] should be mounted at the distal end of a fiber, sacrificing frame-rate and probe size or resolution. Alternatively, 2D image information can be delivered by the different modes of a multimode fiber (MMF), if the complex phase randomization and mode mixing of the MMF is measured and compensated for, computationally or via wavefront-shaping [5,6,7,8,9,10,11,12].…”

Fiber-bundle-basis sparse reconstruction for high resolution wide-field microendoscopy

“…The first method used the DCT as described above, whereas the second method used the point (canonical) basis, and the third the total variation (TV). Both the point basis and total variation basis had been shown to be successful for compressed imaging of beads [23,24]. This is because a sparse sample of beads often leaves much of the image dark making these bases suitably sparse representations.…”