Telescope fibre coupler

This 3D-printed fibre coupler was designed to optically connect a telescope to a spectroscope via a fibre-optic cable. The system enables simultaneous observation through the eyepiece while directing part of the incoming light into an optical fibre for spectral measurements.

The design integrates a 25.4 mm cube beam splitter, a 50 mm focusing lens (L1), and standard 1.25″ telescope fittings. The beam splitter is fully enclosed within the main body, while the lid—secured by two M4 bolts—features an extended 1.25″ tube for attaching the lens adapter. The focusing lens is mounted inside a repurposed Barlow lens adapter which can be found here: https://tinyurl.com/bdfc6u92
The eyepiece slot and lens adapter mount are both designed as 1.25″ hollow cylinders with M4 screw holes for stabilization. An additional threaded part allows mounting of an M16 FC-type fibre connector at the focal point of L1.

All components were modeled in Blender, sliced, and printed using an Elegoo Neptune 2S. The