| 摘要 |
This conduit comprises an axial optical fibre (2) and at least one annular optical fibre (4) which includes an outer peripheral layer (18), one or more internal layers (16) and, possibly, an inner peripheral layer (14). The expansion coefficients of the layers vary, increasing from the outer peripheral layer and, where appropriate, from the inner peripheral layer, towards the internal layer or layers. In order to manufacture this conduit, an annular preform is produced which is capable of generating the annular fibre and the drawing and narrowing-down of the preform are carried out around the axial fibre which may subsequently be removed in order to form a tubular fibre. Application in off-centre spectrometry. <IMAGE>
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