Research On The Shape Measurement Of Reflection Surfaces Based On Optical Lattice

Reflective devices are widely used in areas such as large scientific facilities,microelectronics,modern defense,medical machinery,scientific instruments and high-end consumer products.The effects of surface accuracy on the performance of the device can not be ignored,so the precision measurement of the reflective devices is always been concerned.The existing shape measurement methods still cannot fully meet the needs of precise reflective shape measurement,such as large-scale high-precision shape measurement,online / real-time measurement.Based on this,this paper presents a reflective shape measurement method which based on new structured array,applying the optical lattice to the reflective shape measurement.The two-dimensional optical lattice used in shape measurement is generated by the modulation of optical fields,and its size is adjustable.Calculating the shape of the surface by using the piston of the optical lattice which is modulated by the shape of the surface.It is possible to realize the measurement of the surface shape without obtaining the shape information through the phase,the shape measurement can be realized with only one image,so as to realize the shape measurement of the reflective surface.The method has the characteristics of high precision,fast speed and strong adaptability.The main contents and achievements of this paper are as follows:1.Several methods of reflective shape measurement are studied.The basic principle of optical non-contact measurement method is reviewed,and the characteristics of each measurement method are analyzed.At the same time,the method of generating two-dimensional optical lattice and its application in various fields are summarized.2.A reflective shape measurement method which based on two-dimensional optical lattice is proposed.Based on the theory of geometrical optics and spatial transformation,a mathematic correlation model of two-dimensional optical lattice geometry and reflective three-dimensional surface shape are established.The measurement range and single pixel resolution of the measurement method are analyzed.To verify the feasibility of the mathematical model we proposed,we use the optical simulation software Zemax to simulate the experiment optical path.3.A shape reconstruction algorithm based on two-dimensional optical lattice centroid is proposed.The shape reconstruction algorithm includes threshold segmentation and centroid extraction of the two-dimensional optical lattice images collected by the CCD camera.Finally,the Zernike polynomial model reconstruction algorithm is used to reconstruct the measured surface to realize the measurement of the measured surface.4.Through the experiment to verify the performance of the system.Comparing the surface data which measured by the measure system proposed with the commercial interferometer.Then subtract the surface data measured by the two measurement methods,the surface-mean square error RMS is 0.131?m,which is less than one wavelength,so as to verify the feasibility and accuracy of the shape measurement method proposed in this paper.