02024nas a2200217 4500008004100000245008100041210006900122300001800191490000700209520135300216653000701569653000701576100002601583700002201609700002401631700002501655700001601680700001901696700002301715856006801738 2021 eng d00aSide-view holographic endomicroscopy via a custom-terminated multimode fibre0 aSideview holographic endomicroscopy via a customterminated multi a23083–230950 v293 a

Microendoscopes based on optical fibres have recently come to the fore as promising candidates allowing in-vivo observations of otherwise inaccessible biological structures in animal models. Despite being still in its infancy, imaging can now be performed at the tip of a single multimode fibre, by relying on powerful holographic methods for light control. Fibre based endoscopy is commonly performed en face, resulting in possible damage of the specimen owing to the direct contact between the distal end of the probe and target. On this ground, we designed an all-fibre probe with an engineered termination that reduces compression and damage to the tissue under investigation upon probe insertion. The geometry of the termination brings the field of view to a plane parallel to the fibre&\#x2019;s longitudinal direction, conveying the probe with off-axis imaging capabilities. We show that its focusing ability also benefits from a higher numerical aperture, resulting in imaging with increased spatial resolution. The effect of probe insertion was investigated inside a tissue phantom comprising fluorescent particles suspended in agarose gel, and a comparison was established between the novel side-view probe and the standard en face fibre probe. This new concept paves the way to significantly less invasive deep-tissue imaging.

10aKF10aMF1 aSilveira, Beatriz, M.1 aPikálek, Tomáš1 aStibůrek, Miroslav1 aOndráčková, Petra1 aJákl, Petr1 aLeite, Ivo, T.1 aČižmár, Tomáš uhttp://www.osapublishing.org/oe/abstract.cfm?URI=oe-29-15-2308301412nas a2200205 4500008004100000245006700041210006600108300001800174490000700192520080300199653000701002653000701009100002401016700002201040700002001062700001801082700001801100700002301118856006501141 2019 eng d00aLabel-free CARS microscopy through a multimode fiber endoscope0 aLabelfree CARS microscopy through a multimode fiber endoscope a30055–300660 v273 a

Multimode fibres have recently been employed as high-resolution ultra-thin endoscopes, capable of imaging biological structures deep inside tissue in vivo. Here, we extend this technique to label-free non-linear microscopy with chemical contrast using coherent anti-Stokes Raman scattering (CARS) through a multimode fibre endoscope, which opens up new avenues for instant and in-situ diagnosis of potentially malignant tissue. We use a commercial 125 &\#x00B5;m diameter, 0.29 NA GRIN fibre, and wavefront shaping on an SLM is used to create foci that are scanned behind the fibre facet across the sample. The chemical selectivity is demonstrated by imaging 2 &\#x00B5;m polystyrene and 2.5 &\#x00B5;m PMMA beads with per pixel integration time as low as 1 ms for epi-detection.

10aKF10aMF1 aTrägårdh, Johanna1 aPikálek, Tomáš1 aŠerý, Mojmír1 aMeyer, Tobias1 aPopp, Jürgen1 aČižmár, Tomáš uhttp://www.opticsexpress.org/abstract.cfm?URI=oe-27-21-3005501270nas a2200181 4500008004100000245007300041210006900114300001800183490000700201520071100208653000700919653000700926100002200933700002400955700002100979700002301000856006501023 2019 eng d00aWavelength dependent characterization of a multimode fibre endoscope0 aWavelength dependent characterization of a multimode fibre endos a28239–282530 v273 a

Multimode fibres have recently shown promise as miniature endoscopic probes. When used for non-linear microscopy, the bandwidth of the imaging system limits the ability to focus light from broadband pulsed lasers as well as the possibility of wavelength tuning during the imaging. We demonstrate that the bandwidth is limited by the dispersion of the off-axis hologram displayed on the SLM, which can be corrected for, and by the limited bandwidth of the fibre itself. The selection of the fibre is therefore crucial for these experiments. In addition, we show that a standard prism pulse compressor is sufficient for material dispersion compensation for multi-photon imaging with a fibre endoscope.

10aKF10aMF1 aPikálek, Tomáš1 aTrägårdh, Johanna1 aSimpson, Stephen1 aČižmár, Tomáš uhttp://www.opticsexpress.org/abstract.cfm?URI=oe-27-20-28239