A Research Of 3-D Shape Measurement Based On Triangle Pattern Defocusing

The three-dimensional shape measurement technology based on optics is widely used with its advantage of non-contact,high precision and real-time online detection.Including erospace,automobile manufacturing,industrial production,and many other aspects.However,the present situation of the commonly used measuring system of Gamma effect neither seriously affects the accuracy of measurement,nor ability to make effective measure to mirror object.How to solve the Gamma effect,and improve the accuracy of 3D shape measurement and ability to measure the mirror object is of great importance in modern testing.In traditional method,when binary defocusing is used,adjust the projection equipment commonly used active defocusing or long distance for automatic defocusing.Two defocusing methods mentioned above both have deeper degree of defocus,which reduce the intensity of the projected fringes,then Phase acquisition accuracy is reduce,Which affect the accuracy of measurement.When sinusoidal pattern projection measurement method is used,besause of quite a bit of high harmonic caused by Gamma effect of projector,reducing the quality of fringe and brings to the system measurement error.In order to slove the problems have mentioned above,the main contents and work of this paper are organized as follows:1.Proposing a 3D shape measurement method based on triangular pattern defocusing projection,elaborated on the stripes defocus,Gamma effect and other related issues in detail.In this method,the triangular pattern is slightly defocused by the air,after defocusing the high frequency harmonics with smaller amplitude are filtered out,overcoming the Gamma effect;The defocusing is shorter the higher signal-to-noise ratio is obtained.As a result,phase acquisition is more accurate.MATLAB simulation fully proved the effectiveness and feasibility of the method,the measurement experiment on the mouse and strip objects makes the RMS control within 0.03 mm.Compared with the traditional method,the measurement accuracy has been greatly improved.2.A three-dimensional spherical surface measurement method based on triangularwave defocus fringe reflection is proposed,and the principle of reflection mirror measurement,system structure and system calibration are studied emphatically.This method uses triangular pattern slightly defocusing through short distance by air,not only avoids the problem that CCD camera can not shoot the clear reflection stripe image caused by the long distance defocusing and phase acquisition accuracy rate reduce,but also effectly reduce the measurement error caused by Gamma effect of LCD display.The validity and feasibility of the method are both verified through the simulation and experiment.Experiments are performed on a standard concave mirror with a radius of 1m and a size of 80 mm x 80 mm.The recovery surface RMS is about 16.15 um.