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FUNDING PROGRAM FOR NEXT GENERATION WORLD-LEADING RESEARCHERS Project Title: Real-time optical coherence tomography using ultrafast and ultrabroad fiber sources for medical applications Name: Shinji YAMASHITA Institution: The University of Tokyo 1. Background of research Optical coherence tomography (OCT) is a technique that can obtain tomographic images of living organs. OCT features high-resolution, safety, small size and low cost. It has been already widely used by ophthalmologists. Further improvement in imaging speed is required for wider medical applications. applications 2. Research objectives This project Thi j t aims i att development d l t off real-time l ti OCT systems t using i our original i i l ultra-fast lt f t and d ultra-broad lt b d fiber fib light sources, and their medical applications. 3 Research 3. R h characteristics h t i ti (incl. (i l originality i i lit and d creativity) ti it ) We have two original light sources, one is the ultra-fast and ultra-broad tunable fiber laser based on dispersion tuning, and the other is the nano-carbon-based ultra-broad band white source. The former is the tunable laser whose tuning g speed p is faster byy a few tens of times than the existing g tunable lasers,, and the latter is the ultrabroad fiber supercontinuum (SC) source generated by a low-cost and stable ultra-fast pulse laser using carbon nanotube (CNT) or graphene. 4. Anticipated effects and future applications of research We expect realization of ultra-fast and ultra-high resolution OCT system that could not be achieved with existing light sources, and medical applications to the area where very fast imaging is essential, such as intravascular or visceral i l imaging i i in i conjunction j ti with ith the th catheters th t or endoscopes. d W also We l expectt the th life lif innovation i ti in i terms t of wide spread of low-cost and ubiquitous OCT systems. Background of research: Optical coherence tomography (OCT) X-rayy CT,, MRI ☺ Can image whole body Slow, LowLow-resolution, Large, Costly 10mm ☺ Small, S ll L Low-cost Low- Sl Slow, L Low-resolution, Lowl i Sh Shallow ll iimage Optical coherence tomography (OCT) Resolu ution MRI Ultrasonic CT 1mm X-rayy CT 10μm E l ti off OCT Evolution Swept Source (SS)OCT A Scan Delay=0 Ultrasonic CT 100μm ☺ High High--resolution, Fast, Small, Low Low--cost Very shallow image 1μm Principle: Interference between ref. and scattered lights from sample. Objects: Skin, Teeth, Eye/Fundus, Viscera, Vascula, etc. Time Domain (TD TD) )OCT Reference Arm Thickness of human body OCT 1mm 10mm 100mm 10cm Imaging depth Spectral Domain (SD)OCT Delay=0 ΔL1 ΔL1 Sample Arm Swept Source Low Coherence Source Sample Low Coherence Source Sample B Scan λ Grating Photo Detector PC(FFT) 1st -generation: Moving parts for A-scan, slow Research objectives 1D-CCD 2nd-generation: No moving parts for A-scan, ultra-fast and ultra-high-resolution 2nd gen. OCT performance depends on quality of light sources This p project j aims at development p of real-time SS/SD-OCT systems y using g ultra-fast and ultra-broad fiber sources based on our original mode-locking techniques, and their medical applications. Research characteristics 1. Ultra Ultra--fast dispersiondispersion-tuned fiber lasers No mechanical scanning Ultra-broad band (~200nm), Ultra-high p (>100kHz)) scanning ( g speed Applicable to any kind of lasers at any wavelength Isolator Gain medium Coupler Dispersive element Laser output RF synthesizer fm Controller t Dispersion-tuned fiber laser Ultra-broad band tuning spectra 10mm laser cavity 2 Nano 2. Nano--carbon ultra ultra--fast pulsed lasers Passively mode-locked lasers using saturable absorption in CNT/graphene can generate very stable short pulse (<100fs ) with a very simple construction Applicable to wide wavelength range Ultra-broad band and low-noise fiber supercontinuum (SC) generation Future F t applications li ti off research h High-performance and lowHighlow-cost OCT system g the newly y developed p light g sources using Medical applications: applications:Ultra Ultra--high resolution 3D/4D retinal, intravascular or visceral imaging Pump light HR mirrors Graphene p Carbon nanotube ((CNT)) 10GHz mode-locked spectrum Esophagus p g Brain Kostadinka Bizheva, et al., J. of Biomedical Optics, July/ 2004 Vol.9 No.4 Courtesy of Tsukuba Univ. Petra Wilder-Smith, et al. J. of Biomedical Optics Sep/ 2005 Vol.10 No.5 Tooth Cardiovascular Pancreas Pier Alberto, et al. J Pancreas (Online) 2007 Vol.8 No.2 Yonghong He, et al. J. of Biomedical Optics Jan/ 2004 Vol.9 No.1 Lung Guillermo J. Tearney, et al. J. of Biomedical Optics Mar/ 2006 Vol.11 No.2 Kidney Z.P.Chen, et al., Opt. Express, Aug/ 2007 Vol. 15 No. 16 Alexander Popp, et al., J. of Biomedical Optics, Jan/ 2004 Vol.11 No.1 Cervix Trachea Matthew Brenner, et al., J. of Biomedical Optics, Sep/ 2007 Vol.12 No.5 Cochlea Fangyi Chen, et al., J. of Biomedical Optics, Mar/ 2007 Vol.12 No.2 Colon Stomach Bladder Versatile and ubiquitous OCT system for not only medical but also industrial applications Ultra-broad band SC generation Eye ye Oral World’ss smallest CNT mode-locked laser World Yu Chen, et al. J. of Biomedical Optics Sep/ 2007 Vol.12 No.3 Skin Ying T. Pan, et al. J. of Biomedical Optics Sep/ 2007 Vol.12 No.5 Ilya V. Turchin, et al., J. of Biomedical Optics, Nov/ 2005 Vol.10 No.6 Blood flow Alexandre R. Tumlinson, et al., J. of Biomedical Optics, Nov/ 2006 Vol.11 No.6 Bradley A. Bower., J. of Biomedical Optics, Jul/ 2007 Vol.12 No.4 Bone