| 摘要 |
<p>An optical cable has a central cable (6) provided with four helical grooves in each of which an optical fibre (7) is accommodated. The helical grooves and therefore the optical fibres, reverse their direction of winding periopdically, with an angle periodically with an angle of rotation about the cable axis, between successive reversals, restricted within a range. 275 degrees + 55 degrees + 360 degrees x n where n is zero or a positive integer, and pref. having the value - 275 degrees + 360 degrees x n.</p> |
