LIGHT-CONDUCTING FIBRES OR RODS

摘要

1503793 Optical glass fibres CARL - ZEISS - STIFTUNG [trading as JENAER GLASWERK SCHOTT & GEN] 23 April 1975 [24 April 1964] 16742/75 Heading C1M [Also in Division G2] A light-conducting fibre or rod of improved mechanical strength consists of a core portion 1 and a reflective sheath 2 having a lower R.I. than the core portion and being surrounded by a reinforcing sheath 3, the coefficient of thermal expansion (Á) of which is lower than that of the core and reflective sheath materials. The R.I. of the reinforcing sheath 3 may be higher or lower than that of the reflective sheath portion 2. In the first embodiment (Fig. I ) a fibre has a glass core 1 of Á = 93 Î 10-7 per ‹ C., a reflective sheath 2 ot Á = 96 x 10-7 per ‹ C. and a reinforcing sheath 3 of Á = 53 Î 10-7 per ‹ C. In the second embodiment (Fig. 2, not shown) the core and sheath are as above, but the reflective sheath has Á = 57À5 x 10-7 per ‹ C. and is coloured black to absorb light. The fibre may be of the gradient type, e.g. of quartz. The fibres or rods may be made by the "rodpipe" or double-jet process or by drawing down a tube which has been internally coated with the core glass and has been placed inside a pipe made of the material of the reinforcing sheath.