Design of optical inclinometer composed of a ball lens and viscosity fluid to improve focusing

A new design of optical inclinometer is proposed in this paper. The sensor is composed of a light emitting diode (LED) as a light source, a ball lens on a concave lens as optical system, and a position sensitive detector (PSD). The viscosity fluid is introduced around the ball lens to suppress slight vibration from an installation site and to utilize as another optical system. The ray-trace simulation is introduced to design the optical system. The accuracy of the sensor is estimated to be within 1.60 x 10–
³
degrees. The developed inclinometer will be useful for ensuring vertical and horizontal position inside the building under construction.