Below is a close up of an optical fiber. It is about twice the size of a human hair and makes our spectrograph system possible. Before fibers, spectrographs had to be mounted on the telescopes themselves and move with the optics. With a fiber fed system the spectrograph can be mounted in a controlled environment on a stable base.
Our system uses multiple fibers in sets in order to have backups and do different jobs. The picture below shows the complicated layout of fibers for the Tenagra II telescope. In this design we had the complications of two spectrographs and two reference lamps being fed from one telescope interface. There are two different size fibers running to each spectrograph along with backups in case a fiber breaks.
The picture below shows the polished end of the fibers. This is done by hand and is very time consuming.