Proximity sensors based on ball-lensed optical fibers

In this paper, proximity sensors based on ball-lensed single-mode fibers (SMF) are described. Two types of sensors are presented: (1) Type A with one transmitting and four receiving optical fibers and (2) Type B with one transmitting and eight receiving optical fibers. In both types ball-lensed optical fibers are used as a receiving line. Sensitivity of these sensors is compared to sensitivity of sensors with the same configurations, but involving cleaved optical fibers. All developed sensors were tested at two most popular in SMF wavelengths: 1310 nm and 1550 nm. As a refractive surface the silicon wafer was used