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Optical Fiber Feedthrough for Ultrahigh Vacuum

IP.com Disclosure Number: IPCOM000103184D
Original Publication Date: 1990-Jul-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 1 page(s) / 41K

Publishing Venue

IBM

Related People

Mastro, F: AUTHOR [+3]

Abstract

Disclosed is a method for producing an ultrahigh vacuum feedthrough for an optical fiber. The feedthrough assembly consists of a leak-tight and bakeable glass-to-metal seal between the flange and the quartz fiber and suitable fixturing to prevent breakage of the fiber in vacuum.

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Optical Fiber Feedthrough for Ultrahigh Vacuum

      Disclosed is a method for producing an ultrahigh vacuum
feedthrough for an optical fiber.  The feedthrough assembly consists
of a leak-tight and bakeable glass-to-metal seal between the flange
and the quartz fiber and suitable fixturing to prevent breakage of
the fiber in vacuum.

      Preparation of the fiber requires exposing the bare quartz and
metalizing a portion of the fiber.  The quartz is exposed by
chemically stripping the protective plastic coating from the fiber
for the length of the fiber that will go in vacuum.  A metal coating
is then applied by evaporation onto the portion of the fiber that
will make the seal to the flange.

      To prepare the feedthrough flange, a small diameter, thin-
walled tube that passes through the flange is brazed or welded in
place.  The flange is also configured to mount structures to support
the fragile bare fiber in the vacuum. A means to mount a short length
of tubing that can be attached after the fiber is in place serves
this purpose.

      The joint to the fiber is made by passing the bare end of the
fiber through the small diameter tube until the metalized portion is
inside the vacuum end of the small tube.  Crimping this end of the
thin-walled tube about the fiber and applying a drop of low
temperature, vacuum compatible solder at this point forms a tight
seal to the fiber.  The melting point of the solder should be above
the vacuum chamber bakeou...