Pixel super-resolution of time-stretch imaging by an equivalent-time sampling concept

Optical time-stretch imaging entails a stringent requirement of state-of-the-art high-speed data acquisition unit in order to preserve high image resolution at an ultrahigh frame rate-hampering the widespread application of such technology. We here propose a pixel super-resolution (pixel SR) technique tailored for time-stretch imaging that can relax the sampling rate requirement. It harnesses a concept of equivalent-time sampling, which effectively introduces sub-pixel shifts between frames. It involves no active opto-mechanical subpixel-shift control and any additional hardware. We present the system design rules and a proof-of-principle experiment which restores high-resolution images at a relaxed sampling rate of 5 GSa=s. © 2016 SPIE.published_or_final_versio

Ultrafast, laser-scanning time-stretch microscopy with visible light

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Optical time-stretch confocal microscopy at 1um

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Exploiting few mode-fibers for optical time-stretch confocal microscopy in the short near-infrared window

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Broadband hyperspectral coherent anti-Stokes Raman scattering microscopy for stain-free histological imaging with principal component analysis

Routine procedures in standard histopathology involve laborious steps of tissue processing and staining for final examination. New techniques which can bypass these procedures and thus minimize the tissue handling error would be of great clinical value. Coherent anti-Stokes Raman scattering (CARS) microscopy is an attractive tool for label-free biochemical-specific characterization of biological specimen. However, a vast majority of prior works on CARS (or stimulated Raman scattering (SRS)) bioimaging restricted analyses on a narrowband or well-distinctive Raman spectral signatures. Although hyperspectral SRS/CARS imaging has recently emerged as a better solution to access wider-band spectral information in the image, studies mostly focused on a limited spectral range, e.g. CH-stretching vibration of lipids, or non-biological samples. Hyperspectral image information in the congested fingerprint spectrum generally remains untapped for biological samples. In this regard, we further explore ultrabroadband hyperspectral multiplex (HM-CARS) to perform chemoselective histological imaging with the goal of exploring its utility in stain-free clinical histopathology. Using the supercontinuum Stokes, our system can access the CARS spectral window as wide as >2000cm-1. In order to unravel the congested CARS spectra particularly in the fingerprint region, we first employ a spectral phase-retrieval algorithm based on Kramers–Kronig (KK) transform to minimize the non-resonant background in the CARS spectrum. We then apply principal component analysis (PCA) to identify and map the spatial distribution of different biochemical components in the tissues. We demonstrate chemoselective HM-CARS imaging of a colon tissue section which displays the key cellular structures that correspond well with standard stained-tissue observation. © 2014 SPIE.published_or_final_versio

Optical time-stretch microscopy using few-mode fibers

(Oral) Session MB: Microscopy and Imaging: MB3We demonstrate a cost-effective and efficient approach for realizing ultrafast time-stretch microscopy in 1μm using the standard telecommunication single-mode fibers (e.g. SMF28 and dispersion compensation fiber (DCF)) as few-mode fibers (FMFs). © 2012 IEEE.published_or_final_versionThe 2012 IEEE Photonics Conference (IPC), Burlingame, CA., 23-27 September 2012. In IEEE - LEOS Annual Meeting of the Lasers and Electro-Optics Society Proceedings, 2012, p. 4-

Stabilized Wide-band Wavelength Conversion Enabled by CW-Triggered Supercontinuum

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Speed-dependent resolution analysis of ultrafast laser-scanning fluorescence microscopy

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Megahertz all-optical swept-source optical coherence tomography based on broadband amplified optical time-stretch

We demonstrate all-optical ultrahigh-speed swept-source optical coherence tomography (OCT) based on amplified optical time-stretch (AOT). Such an inertia-free wavelength-swept mechanism, via group velocity dispersion, enables us to realize OCT with an A-scan rate well above MHz. More importantly, the key significance of AOT-OCT is its simultaneous broadband Raman amplification during the time-stretch process-greatly enhancing the detection sensitivity compared with prior attempts to apply optical time-stretch to OCT. Here, we report on an AOT-OCT system which is operated at an A-scan rate of 7.14 MHz, a superior roll-off performance (>2 mm/dB), a record-high sensitivity of time-stretch-based OCT (>80 dB) with a broadband gain bandwidth of 80 nm, which results in an axial resolution of approximately 15 mum. Our AOT-OCT system is thus able to, for the first time to the best of our knowledge, perform time-stretch-based OCT of biological tissue in vivo. It represents a major step forward in utilizing AOT as an alternative for achieving practical MHz OCT, without any long-term mechanical stability concerns as in typical swept-source OCT or bypassing the speed limitation of the image sensor employed in spectral-domain OCT.published_or_final_versio

Time-stretch microscopy based on time-wavelength sequence reconstruction from wideband incoherent source

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