Light source modifications for plastic light fibre compatibility

摘要

Apparatus for coupling a light beam from a light source to a light fibre with reduced heating of the light fibre. The light source has a lamp, a condenser lens, and a dichroic infra-red filter disposed along an optical axis between the lamp and the light fibre. The apparatus is adapted for operation with plastic light fibres that have a softening temperature of less than 100 degrees Celsius. The apparatus comprises light fibre connector that secures the light fibre on the optical axis. A non-visible radiation filter is located on the optical axis in a broad part of the light beam between the dichroic filter and the light fibre and reduces non-visible radiation energy remaining in the light beam following the dichroic filter. A beam restrictor is located on the optical axis adjacent to, and thermally isolated from, the light fibre connector. The beam restrictor restricts the light beam to an extent approximately equal to the extent of the light fibre and minimizes the amount of the light beam falling on the light fibre connector. This minimizes heating of the light fibre connector by the light falling on the light fibre connector. Finally, the apparatus includes an element that transfers heat from the beam restrictor for dissipation at a location thermally isolated from the light fibre connector to prevent heat resulting from the light absorbed by the beam restrictor from being transferred to the light fibre.