Protective tube arrangement for a glass fiber

Claim 1

In a protective tube arrangement for a glass fiber, said tube arrangement being particularly useful for mounting in a housing of a module, said tube arrangement including a glass fiber having a taper at one end and being positioned in a stiff protective tube with the tube surrounding and protecting the glass fiber and holding it in alignment with the taper extending from one end of the tube, and the module having an operating temperature and a storage temperature which have a maximum temperature limit and a minimum temperature limit, the improvements comprising stiff first means for securing the fiber in the proximity of the taper to the tube at a first location and second means for securing the fiber to the tube at a second location spaced from the first location with the fiber being free of any means for securing between the first and second locations, said locations on the tube and on the glass fiber being selected with the length of the fiber between the first and second locations being greater than the distance of the tube between the locations at any temperature below the maximum temperature limit so that the fiber is substantially free of tensile stresses and said length and distance are selected so that at a temperature below the maximum temperature limit and above the minimum temperature limit, the glass fiber hangs loosely in the tube between the two locations and the only stresses on the fiber are axially directed compressive stresses of below 1 N/mm 2 so that no triggering of creep even over a long period of time will occur to cause misalignment and damage.