High density optical cable

An optical fiber cable having a minimum bend radius and comprising at least one U-shaped carrier helically stranded at a first helix angle .theta..sub.0 and a first handedness about a central rod having a central axis and including in its lateral peripheral surface at least one groove proceeding helically at a second helix angle .theta..sub.i and a second handedness, said groove containing at least one optical fiber element, said second handedness is the same as said first handedness and .vertline..theta..sub.0 -.theta..sub.i .vertline. is greater than a predetermined angle whereby upon bending of said optical fiber cable said U-shaped carrier does not buckle and intrude into said at least one groove.

An optical fiber cable having a minimum bend radius and comprising at least one U-shaped carrier helically stranded at a first helix angle .theta..sub.0 a central rod having a central axis and including in its lateral peripheral surface at least one groove having an alternating direction of lay comprising a second helix angle .theta..sub.i, said groove containing at least one optical fiber element,

• sin.sup.2 .phi.>, where
• .phi.=.vertline..theta..sub.0 -.theta..sub.i .vertline., .theta..sub.0 .noteq..theta..sub.i, r.sub.u is the distance between said rod central axis and the centroid of a cross-section of said U-shaped carrier, A is the area of said U-shaped carrier cross-section, w is the width of said groove at said rod lateral peripheral surface, m is said cable minimum bend radius, and I is the moment of inertia of said U-shaped carrier about a line which contains said centroid and is tangent to the circle of radius r.sub.u which contains said centroid and whose center is located on said rod central axis.

An optical fiber cable having a minimum bend radius and comprising at least one U-shaped carrier comprising a first helix angle .theta..sub.0 whereby the U-shaped carrier is stranded about a central rod having a central axis and including in its lateral peripheral surface at least one groove comprising a second helix angle .theta..sub.i, said groove containing at least one optical fiber element, the maximum compressive force on said U-shaped carrier caused by bending the cable to its minimum bend radius is less than the minimum such force which could cause said U-shaped carrier to buckle toward said groove and wherein sin.sup.2 .phi.>›r.sub.u A w.sup.2 /(4 .pi..sup.2 I m)!, where .phi. is a function of (.theta..sub.0, .theta..sub.I), r.sub.u is the perpendicular distance between said rod central axis and the centroid of a cross-section of said U-shaped carrier, A is the area of said U-shaped carrier cross-section, w is the width of said groove at said rod lateral peripheral surface, m is said cable minimum bend radius, and I is the moment of inertia of said U-shaped carrier about a line which contains said centroid and is tangent to the circle of radius r.sub.u which contains said centroid and whose center is located on said rod central axis.

An optical fiber cable having a minimum bend radius and comprising at least one U-shaped carrier stranded with an alternating direction of lay comprising a first helix angle .theta..sub.0 about a central rod having a central axis and including in its lateral peripheral surface at least one helical groove comprising a second helix angle .theta..sub.i, said groove containing at least one optical fiber element, the maximum compressive force on said U-shaped carrier caused by bending the cable to its minimum bend radius is less than the minimum such force which could cause said U-shaped carrier to buckle toward said groove.

An optical fiber cable having a minimum bend radius and comprising at least one U-shaped carrier stranded with an alternating direction of lay comprising a first helix angle .theta..sub.0 about a central rod having a central axis and including in its lateral peripheral surface at least one groove, said groove having an alternating direction of lay comprising a second helix angle .theta..sub.i and containing at least one optical fiber element, the maximum compressive force on said U-shaped carrier caused by bending the cable to its minimum bend radius is less than the minimum such force which could cause said U-shaped carrier to buckle toward said groove.

An optical fiber cable having a minimum bend radius and comprising at least one U-shaped carrier comprising a first helix angle .theta..sub.0 whereby the U-shaped carrier is stranded about a central rod having a central axis and including at least one groove comprising a second helix angle .theta..sub.i, said groove containing at least one optical fiber element, the maximum compressive force on said U-shaped carrier caused by bending the cable to its minimum bend radius is less than the minimum such force which could cause said U-shaped carrier to buckle toward said groove and wherein sin.sup.2 .phi.>›r.sub.u A w.sup.2 /(4 .pi..sup.2 I m)!, where .phi. is a function of (.theta..sub.0, .theta..sub.I) r.sub.u is the perpendicular distance between said rod central axis and the centroid of a cross-section of said U-shaped carrier, A is the area of said U-shaped carrier cross-section, w is the width of said groove at said rod lateral peripheral surface, m is said cable minimum bend radius, and I is the moment of inertia of said U-shaped carrier about a line which contains said centroid and is tangent to the circle of radius r.sub.u which contains said centroid and whose center is located on said rod central axis.