Profile Extraction Algorithm Researches And Software Implementation Of Discrete Curve Surface Based On Confocal Scanning

In order to meet increasing requirements of modern optical system, the structure design of optical element becomes richer and richer, and the surface shape accuracy is higher and higher, so that a bigger challenge is proposed to the surface contour detection of the optical element. The emergence and application of aspherical basal diffraction optical elements can reduce volume and weight of optical systems. At the same time, it can effectively correct aberration, realize the miniaturization and compact of the complex optical systems,therefore,it is paid great attention in precision optical field, and is applied to many systems such as advanced weapons and equipment, astronomical observation, the space detection, etc.The profile characteristics of aspherical basal diffraction optical elements are large caliber, discontinuous surface and macro dimension with micro structure.Whether the realization of high precision measurement can be achieved determines whether this type of elements can be large-scale processing and widely used or not. So it is more and more urgent to realize the high precision contour measurement of this type of optical elements.This subject "Profile Extraction Algorithm Researches and Software Implementation of Discrete Curve Surface based on Confocal Scanning" realized the 2D profile measurement and contour extraction of aspheric basal diffraction elements by using confocal scanning principle, mainly studied the step edge interpretation measured by confocal scanning, and the bench height calculation methods based on curved-surface substrate, wrote the measurement software based on Lab VIEW platform. The main completed content is as follows:(1) Analyze the busbar outline characteristics of harmonic diffractive elements with aspheric basement, then develope the research on step edge interpretation measured by confocal scanning and the bench height calculation methods based on curved-surface substrate, and propose a judgment of step edge locatio by using maximum intensity value and a method to calculate steps with high degree of polynomial regression.(2) Carry out the overall design of measuring instrument based on confocal scanning profile, and complete the design of confocal scanning optical path, the scheme design of motor system and the hardware selection of control feedback system and data acquisition system.(3) Carry out the written work of system software based on Lab VIEW platform, and it has realized the function of the aspherical basal diffraction element measurement, continuous surface element measurement and the confocal 3D imaging scans.(4) Carry out the experiments of single point measurement ability and single point measurement repeatability experiment in confocal scanning, then verify the ability of 3D confocal scanning measurement. Next,verify the accuracy of curved face basal step height calculation algorithm, and compare the measurement results with Taylor- Hobson, the results showed that the bench height calculation result difference was no more than 50 nm. Finally,prove the ability of compensation processing for infrared aspherical basal diffraction elements and aspheric elements. The results showed that it can make the final machining of components surface profile error PV value below 700 nm by compensating using the measured data of this system.