title: A flexible wide-field FLIM endoscope utilising blue excitation light for label-free contrast of tissue.
abstract: Fluorescence lifetime imaging (FLIM) has previously been shown to provide contrast between normal and diseased tissue. Here we present progress towards clinical and preclinical FLIM endoscopy of tissue autofluorescence, demonstrating a flexible wide-field endoscope that utilised a low average power blue picosecond laser diode excitation source and was able to acquire ∼mm-scale spatial maps of autofluorescence lifetimes from fresh ex vivo diseased human larynx biopsies in ∼8 seconds using an average excitation power of ∼0.5 mW at the specimen. To illustrate its potential for FLIM at higher acquisition rates, a higher power mode-locked frequency doubled Ti:Sapphire laser was used to demonstrate FLIM of ex vivo mouse bowel at up to 2.5 Hz using 10 mW of average excitation power at the specimen.
authors.affiliation: Photonics Group, Physics Department, Imperial College London, London SW7 2AZ, UK. hugh.sparks10@imperial.ac.uk.
authors.forename: Hugh
authors.initials: H
authors.lastname: Sparks
authors.forename: Sean
authors.initials: S
authors.lastname: Warren
authors.forename: Joana
authors.initials: J
authors.lastname: Guedes
authors.forename: Nagisa
authors.initials: N
authors.lastname: Yoshida
authors.forename: Tze Choong
authors.initials: TC
authors.lastname: Charn
authors.forename: Nadia
authors.initials: N
authors.lastname: Guerra
authors.forename: Taranjit
authors.initials: T
authors.lastname: Tatla
authors.forename: Christopher
authors.initials: C
authors.lastname: Dunsby
authors.forename: Paul
authors.initials: P
authors.lastname: French
mesh_terms: D000818:Animals; D003116:Color; D019723:Endoscopes; D005456:Fluorescent Dyes / Q000378:metabolism; D006801:Humans; D007414:Intestinal Neoplasms / Q000473:pathology; D007830:Larynx / Q000166:cytology / Q000378:metabolism; D008027:Light; D051379:Mice; D061848:Optical Imaging / Q000295:instrumentation*
chemical_list: D005456:Fluorescent Dyes
keywords: FLIM; autofluorescence; endoscope; fibre; flexible; instrument; lifetime