title: Double-clad fiber coupler for endoscopy.
abstract: We present a double-clad fiber coupler (DCFC) for use in endoscopy to reduce speckle contrast, increase signal collection and depth of field. The DCFC is made by fusing and tapering two all silica double-clad fiber (DCF) and allows achromatic transmission of >95% of core illumination (1265nm - 1325nm) as well as collection of >42% of inner cladding diffuse light. Its potential for endoscopy is demonstrated in a spectrally encoded imaging setup which shows speckle reduction by a factor 5, increased signal collection by a factor 9 and enhanced depth of field by 1.8 times. Separation by the DCFC of single- and multi-mode signals allows combining low-speckle reflectance images (25.5 fps) with interferometrically measured depth profiles (post-processed) for of small three-dimensional (3D) features through an all-fiber low loss instrument.
authors.affiliation: Centre d'Optique, Photonique et Laser, Engineering Physics Department, Ecole Polytechnique de Montréal, Station Centre-ville, Montreal, Quebec, Canada.
authors.forename: Simon
authors.initials: S
authors.lastname: Lemire-Renaud
authors.forename: Maxime
authors.initials: M
authors.lastname: Rivard
authors.forename: Mathias
authors.initials: M
authors.lastname: Strupler
authors.forename: Dominic
authors.initials: D
authors.lastname: Morneau
authors.forename: Frédéric
authors.initials: F
authors.lastname: Verpillat
authors.forename: Xavier
authors.initials: X
authors.lastname: Daxhelet
authors.forename: Nicolas
authors.initials: N
authors.lastname: Godbout
authors.forename: Caroline
authors.initials: C
authors.lastname: Boudoux
mesh_terms: D019723:Endoscopes; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005336:Fiber Optic Technology / Q000295:instrumentation*; D007089:Image Enhancement / Q000295:instrumentation*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity