This paper presents the design of an optical fiber proximity sensor for haptic exploration with a robotic finger. The sensor uses emitter and receiver optical fiber pairs to measure the intensity of light reflected off surrounding objects in a 2-D workspace. We present the design and construction a 32-point sensor array mounted within a 36 mm diameter finger and describe software techniques to process data acquired by an inexpensive web-cam. We experimentally characterize the sensor performance and demonstrate applications for haptic exploration such as pre-contact velocity reduction and non-contact contour following based on object curvature.