Application of cylindrical lenses in small angle measurement

In order to realize three-dimensional(3D) angle measurement, a photoelectric method using cylindrical lens is presented. First, based on the principle of auto-collimation, a pair of cylindrical lens and a tetrahedral reflector are used instead of a plane mirror to indicate the change of pitch, yaw and roll. Then after the analysis with matrix theory, the relationship between shape and position of the light beam and the angles to be measured is revealed, followed by the algorithm and parameter analysis. Finally, an experiment for roll angle measurement is conducted to test and verify this method. Experimental results show that the system has a range of 20' and an accuracy of error RMS(Root Mean Square) superior to 8" at a working distance of 1.2 m, which can basically satisfy the requirements of non-contact small angle measurement, and has certain practical value in engineering.