The IAC Fibre Optics Laboratory's main objective is the construction of fibre optic bundles for astronomical research applications. Its floor area is approximately 12 m2 and it has security systems suitable for working with joining materials such as epoxy and materials used in polishing processes.
The fibres are manually assembled using appropriate optical instruments. Specially designed tools are normally used in the assembly process as the fibres can be as small as 50 microns in diameter. To attach fibres to one another dual-component semi-fast drying adhesives are used, with setting times of between 20 minutes and four hours. The drying temperature for these adhesives ranges from 60ºC to 65ºC so that the drying time varies from 15 minutes to 2 hours depending on the type.
Polishing is carried out by a timer-controlled polisher (left), which can operate at up to 360 r.p.m. It has an arm to which accessories can be fitted for aligning and counterweighting the piece being worked on, as well as for adding the weight needed for the surface being polished to exert sufficient pressure on the spinning disc containing the abrasive.
The polishing process can vary considerably depending on requirements. Normally, and for generic polishing, an abrasive like fine sandpaper (1,200) is used in the initial phases to remove the main defects in the surface to be polished. After this begins a mechanical polishing process using diamond paste abrasives with different grain sizes, giving results that would be impossible to produce manually. The process begins with a grain size of 25 microns, moving through 14, 6, 3, 1, 0.4 and finally 0.1 microns. Each stage normally takes three hours. From 6 microns on, the quality of the polishing is repeatedly tested using a microscope. These tests may take several hours and their complexity increases as the grain size reduces.