A simple servo-controlled scanning fibre-optic confocal microscope is proposed for determining the refractive index profile of an optical fibre by measuring the reflectance of the end surface of the fibre. Great simplicity has been achieved in confocal microscopy by using a lensed fibre and a 3 dB fibre coupler instead of an objective lens and a beam splitter. A dithering servo control with a phase-locked loop is employed to maintain a constant distance between the lensed fibre and the surface to be measured during the scanning process. The accuracy of the measured refractive index is better than 10-4.
All Science Journal Classification (ASJC) codes
- Engineering (miscellaneous)
- Applied Mathematics