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Browse Prior Art Database

Optical Technique for Accurately Measuring Single Mode Fiber Lens Radii

IP.com Disclosure Number: IPCOM000109951D
Original Publication Date: 1992-Sep-01
Included in the Prior Art Database: 2005-Mar-25
Document File: 2 page(s) / 69K

Publishing Venue

IBM

Related People

Goodman, D: AUTHOR [+3]

Abstract

An optical technique is disclosed for quickly and accurately determining the radius of a lensed single-mode fiber.

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This is the abbreviated version, containing approximately 59% of the total text.

Optical Technique for Accurately Measuring Single Mode Fiber Lens Radii

      An optical technique is disclosed for quickly and accurately
determining the radius of a lensed single-mode fiber.

      One of the important characteristics of tapered single-mode
fibers is the radius of curvature of the lens at the fiber end that
is produced during the taper drawing procedure.  It is very difficult
and time consuming to measure the radius using conventional methods
such as scanning electron microscopy.

      Fig. 1 schematically depicts the apparatus used for measuring
the radius of tapered lens single-mode fibers.  It consists of a
modified microscope.  A fiber with a tapered lens end is placed in
the microscope.  The surface of the fiber lens is brought into focus.
Simultaneously, a 50 mm (or less) pinhole is imaged through the
microscope objective onto the curved fiber surface.  This is observed
either through eyepieces or a video monitor as a sharply focussed
spot roughly 0.5 mm in diameter.  The fiber is mounted on a high
resolution (50 nm) motor-driven stage and can therefore be very
precisely moved parallel to the optical axis of the microscope
objective.  While keeping all of the microscope settings constant,
the fiber is moved towards the lens.  At first, the sharp image of
the pinhole goes out of focus.  But, at a position within the fiber
tip at which the focus point falls at the center of curvature of the
fiber lens sphere, a sharp image will b...