Photonic Sensor for railway track safety

This paper brings out the necessity of a sensor system to monitor world's 4 th largest railway network, running through urban and remote rural parts of India, and thereby, avoid accidents by effective surveillance of this national asset. The paper discusses available sensor technologies and proposes a sensor configuration suitable for 24/7 (day - night) operation under different weather conditions. In order to permit track surveillance covering across atmospheric (fair weather, haze, smoke, and CAT-I Fog) and illumination (day/night and seasonal variation) conditions, pulsed illuminator with In 0.53 Ga 0.47 As/Si hybrid focal plane array with pixelated polarizer is proposed. The proposed approach would provide both intensity and depth map of target along with polarization. The brief design of the InGaAs focal plane array (FPA) fusion bonded with Si based CCD readout is discussed. This paper also discusses overall system level performance that could be achieved using the proposed FPA.