Novel Optical Sensor for Precise Tilt Angle Measurement

A novel optical sensor, which can measure inclination angle or tilt angle of two axes simultaneously and precisely, is introduced. This sensor is based on the principle of laser interference so it has very high accuracy. A prototype sensor is designed, built and evaluated to demonstrate the novel concept. It is an opto-electronic sensor. There are no moving parts in the sensor. A fluid horizontal that is absolutely perpendicular to the true vertical provides the reference plane. The angle between the sensor and the absolute horizon changes with the inclination of the object being measured. These changes are reflected in the way of fringe pattern's centre position shift. Different interference patterns centre locations are generated when tilt angle varied. The interference fringe pattern are recorded and processed to translate into the tilt angles of two axes, horizontal and vertical. The accuracy can reach as high as +/- 1 arc second with the measurement range of 700 arc seconds when 1024 by 1024 pixels image sensor is utilized