Development of a low cost optical tilt sensor

The paper deals with the theory, design, fabrication and test results of a Fiber optic tilt sensor. The sensor is based upon the modulation of light intensity with the change in the level of mercury (Hg) surface with tilt. 650 nm light-emitting diode (LED) is used as light source and the reflected light is detected by light dependant resistor (LDR). The output of the receiver circuit is directly proportional to the tilt angle. The sensitivity of the two probe sensor is 0.013 V mrad^-1 and the maximum range covered is 53.4 mrad. The sources of error and their minimization have been discussed.