Summary
A direct microscopic method for determination of birefringence in polarization‐maintaining optoelectronic fibres has been developed. The fibre, approximately 0·15 mm in diameter, is embedded in a suitable resin (epoxy). A thin section (approximately 3 mm in thickness) is then cut perpendicular to the fibre axis, ground and polished. Birefringent patterns (isochromatic fringes) can be seen and photographed using a light‐polarizing microscope with appropriate magnification. A method for performing a quantitative analysis of birefringence in real optoelectronic fibres using a macroscopic model is indicated.