title: Ultrathin side-viewing needle probe for optical coherence tomography.
abstract: We present the smallest reported side-viewing needle probe for optical coherence tomography (OCT). Design, fabrication, optical characterization, and initial application of a 30-gauge (outer diameter 0.31 mm) needle probe are demonstrated. Extreme miniaturization is achieved by using a simple all-fiber probe design incorporating an angle-polished and reflection-coated fiber-tip beam deflector. When inserted into biological tissue, aqueous interstitial fluids reduce the probe's inherent astigmatism ratio to 1.8, resulting in a working distance of 300 μm and a depth-of-field of 550 μm with beam diameters below 30 μm. The needle probe was interfaced with an 840 nm spectral-domain OCT system and the measured sensitivity was shown to be only 7 dB lower than that of a comparable galvo-scanning sample arm configuration. 3D OCT images of lamb lungs were acquired over a depth range of ~600 μm, showing individual alveoli and bronchioles.
authors.affiliation: Optical+Biomedical Engineering Laboratory, School of Electrical, Electronic & Computer Engineering, The University of Western Australia, WA 6009, Australia. dirk.lorenser@uwa.edu.au
authors.forename: D
authors.initials: D
authors.lastname: Lorenser
authors.forename: X
authors.initials: X
authors.lastname: Yang
authors.forename: R W
authors.initials: RW
authors.lastname: Kirk
authors.forename: B C
authors.initials: BC
authors.lastname: Quirk
authors.forename: R A
authors.initials: RA
authors.lastname: McLaughlin
authors.forename: D D
authors.initials: DD
authors.lastname: Sampson
mesh_terms: D000818:Animals; D002417:Cattle; D019723:Endoscopes; D004724:Endoscopy / Q000295:instrumentation* / Q000379:methods; D004867:Equipment Design; D005260:Female; D005336:Fiber Optic Technology / Q000295:instrumentation* / Q000379:methods; D021621:Imaging, Three-Dimensional; D008168:Lung / Q000166:cytology; D008904:Miniaturization; D055100:Optical Fibers; D011247:Pregnancy; D012680:Sensitivity and Specificity; D041623:Tomography, Optical Coherence / Q000295:instrumentation* / Q000379:methods