IPC Definitions - January 01, 2012
E21B 47/135 - Definition
This group covers:
Processes or apparatus the transmission link is via the infrared, visible or ultraviolet part of the electromagnetic spectrum.
Attention is drawn to the following places, which may be of interest for search:
Optical transmission in general | H04B 10/00 |
Light guides, e.g. optical fibres | G02B 6/00 |