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Apparatus for Determining Beam Centrality in Connectorized Fiber-Optic Packages

IP.com Disclosure Number: IPCOM000122137D
Original Publication Date: 1991-Nov-01
Included in the Prior Art Database: 2005-Apr-04
Document File: 3 page(s) / 119K

Publishing Venue

IBM

Related People

Danovitch, D: AUTHOR [+5]

Abstract

An apparatus is disclosed which can serve as a diagnostic tool for rapidly and simultaneously determining the key parameters governing the optical performance of connectorized fiber-optic subassemblies including laser spot size, bore size, position of laser spot with respect to the bore center, and coupled power.

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Apparatus for Determining Beam Centrality in Connectorized Fiber-Optic
Packages

      An apparatus is disclosed which can serve as a diagnostic
tool for rapidly and simultaneously determining the key parameters
governing the optical performance of connectorized fiber-optic
subassemblies including laser spot size, bore size, position of laser
spot with respect to the bore center, and coupled power.

      Alignment of the optical elements in a single-mode fiber-optic
package is crucial for ensuring proper light coupling into a fiber.
This is especially true for connectorized subassemblies where light
from a laser is focused onto a fiber via a lens (see, e.g., Fig. 1).
In order to obtain the proper level of coupling, tolerance, and
repeatability between units, precise control must be kept over key
parameters, such as laser spot size, package bore diameter, position
of the laser spot with respect to the bore, etc.  It is well
understood that small (i.e., micron-size) variations in any of these
parameters can affect coupled power and coupling repeatability.
Instruments and techniques have been devised to measure and determine
these parameters.  However, each technique is capable of determining
only one of these parameters.  Thus, any attempt to understand the
cause of failure of a given part or perform a quality inspection
requires a time- consuming, multi-step testing and correlation
procedure.

      The present invention claims the capability of performing all
of these measurements in a rapid time and with a resolution
sufficient for supporting a single-mode connectorized fiber-optic
package.

      A schematic of the invention is depicted in Fig. 2 (bottom).
The connectorized fiber-optic package such as a "transmitter optical
subassembly" (TOSA) is mounted on a precision computer controlled
x-y-z stage.  A viewing microscope interfaced to an image processing
unit is used to observe the TOSA part as it is scanned.  An objective
lens of numerical aperture of ca. 0.2 captures only a small area of
the part at any given time. Thus, to measure the bore diameter, e.g.,
a video image of one corner (arc) of the bore is captured.  The part
is then moved to another position and another image is taken as
depicted in Fig. 2 (top).  By capturing several images an...