| 摘要 |
A first (1) and a second (4) optical fibre are each retained in its holder (2, 5) by which the ends of the fibres may be centered at a contact location (6). Each of the fibres is bent at a radius (R1) dependent on the light wavelength in its respective light coupling means (8, 9) for coupling light to the fibres. Light from a light source (11) passes the contact location (6) and is measured with the aid of a light detector (14) and a measuring instrument (16). For each fibre (1, 4) the apparatus has a mode filter including a cylinder (17, 18) about which the fibre is bent half a turn. This cylinder has a radius (R2) which is greater than the cylinder radius (R1) in the light coupling means. A light signal (I1) has a basic mode (I2) with symmetric energy distribution, which passes through the first mode filter (17), while higher order unsymmetric modes (I'1) are filtered away. A light signal (I3) in the second fibre (4) has higher order modes (I'3) generated at the contact location, these modes being filtered away in the second mode filter (18), so that a light signal (I4) with only basic modes actuates the detector (14). A splice with low signal attenuation may be obtained by only using the symmetric basic mode during detection of the fibre centering.
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