90 research outputs found
Ultra-thin rigid endoscope: Two-photon imaging through a graded-index multi-mode fiber
Rigid endoscopes like graded-index (GRIN) lenses are known tools in
biological imaging, but it is conceptually difficult to miniaturize them. In
this letter, we demonstrate an ultra-thin rigid endoscope with a diameter of
only 125 microns. In addition, we identify a domain where two-photon endoscopic
imaging with fs-pulse excitation is possible. We validate the ultra-thin rigid
endoscope consisting of a few cm of graded-index multi-mode fiber by using it
to acquire optically sectioned two-photon fluorescence endoscopic images of
three-dimensional samples.Comment: 17 pages, 15 figures, submitted to Opt. Expres
Extended field-of-view in a lensless endoscope using an aperiodic multicore fiber
We investigate lensless endoscopy using coherent beam combining and aperiodic
multicore fibers (MCF). We show that diffracted orders, inherent to MCF with
periodically arranged cores, dramatically reduce the field of view (FoV) and
that randomness in MCF core positions can increase the FoV up to the
diffraction limit set by a single fiber core, while maintaining MCF
experimental feasibility. We demonstrate experimentally pixelation-free
lensless endoscopy imaging over a 120 micron FoV with an aperiodic MCF designed
with widely spaced cores. We show that this system is suitable to perform beam
scanning imaging by simply applying a tilt to the proximal wavefront.Comment: Submitted to Optics Letter
All-fiber transform-limited spectral compression by self-phase modulation of amplitude shaped pulses
International audienceWe demonstrate efficient spectral compression of picosecond pulses in an all-fiber configuration at telecommunication wavelengths. Thanks to parabolic pulse shaping, a spectral compression by a factor 12 is achieved with an enhanced Strehl ratio
Single-shot non-interferometric measurement of the phase transmission matrix in multicore fibers
A simple technique for far-field single-shot non-interferometric
determination of the phase transmission matrix of a multicore fiber with over
100 cores is presented. This phase retrieval technique relies on the aperiodic
arrangement of the cores.Comment: Submitted to Optics Letter
Flexible lensless endoscope with a conformationally invariant multi-core fiber
The lensless endoscope represents the ultimate limit in miniaturization of
imaging tools: an image can be transmitted through a (multi-mode or multi-core)
fiber by numerical or physical inversion of the fiber's pre-measured
transmission matrix. However, the transmission matrix changes completely with
only minute conformational changes of the fiber, which has so far limited
lensless endoscopes to fibers that must be kept static. In this letter we
report for the first time a lensless endoscope which is exempt from the
requirement of static fiber by designing and employing a custom-designed
conformationally invariant fiber. We give experimental and theoretical
validations and determine the parameter space over which the invariance is
maintained
Flexible lensless endoscope with a conformationally invariant multi-core fiber
International audienceThe lensless endoscope represents the ultimate limit in miniaturization of imaging tools: an image can be transmitted through a (multi-mode or multi-core) fiber by numerical or physical inversion of the fiber's pre-measured transmission matrix. However, the transmission matrix changes completely with only minute conformational changes in the fiber, which has so far limited lensless endoscopes to fibers that must be kept static. In this paper, we report for the first time, to the best of our knowledge, a lensless endoscope that is exempt from the requirement of static fiber by designing and employing a custom-designed conformationally invariant fiber. We give experimental and theoretical validations and determine the parameter space over which the invariance is maintained
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