A Research On Three-dimensional Angle Measurement Based On Anamorphic Effect

In many fields of engineering, a number of sophisticated measuring equipment and fundamental devices, for special requirements of system, are often dispersed in separate locations. With a variety of external interference, three-dimensional small angle deformation exists between these devices, which has a negative impact on the accuracy of the measuring equipment. Therefore, the angular deformation must be measured and amended. There are two request for structural deformation measurement: a long working distance and measuring three dimensional angles at the same time.First, several conventional methods for small angle measuring are introduced, and their advantage and disadvantage in structural deformation measuring. With all factors considered, an autocollimator is chosen for measuring pitch and yaw. As for roll angle, we propose a new optical method with high precision and long working distance, followed with theoretical analysis, mathematical derivation and software simulation.This method is based on the idea of measuring rotation angle with anamorphic effect created by cylindrical lenses and a tetrahedral retro-reflector, and combined with autocollimator for yaw and pitch measuring. Thus a real-time method for three dimensional angular deformation measurement is presented.To process the images captured in experiments, following procedure is noted: low-pass filtering, threshold segmentation, edge detection, and line extraction. With all these process done, the parameters for roll angle calculation will be obtained from the images.Under the current condition, proper equipment and devices are chosen to set up the experiment platform. The experimental result shows that the measuring errors of roll angle is under 14″ when roll angle changes in the field of 1200′′.In a word, this dissertation proposed a proper 3-D angle measurement method for structural deformation. Furthermore, as angle measurement is an important part of metrology, this method may find its applications in many other fields, e.g. optical engineering,mechanical manufacturing, aeronautics, military engineering, etc.