| Subject | English | German |
| opt. | core-sheath interface | Grenzschicht Kern-Mantel |
| opt. | interface between core and sheath | Grenzschicht Kern-Mantel (of a fibre optic light guide) |
| opt. | interface between core and sheath | Trennfläche zwischen Kern und Mantel (fibre optics) |
| opt. | interface between core and sheath | Grenzfläche zwischen Kern und Mantel (of a fibre optic light guide) |