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摘要
为了解决传统白光干涉测量技术中对线性位移机构的位移精度要求过高的问题,本文提出了一种全视场外差白光干涉测量技术。该技术主要通过使用存在差频的白光干涉信号作为光源来实现在大扫描步长和低扫描精度条件下相干峰位置的高精度检测。本文首先建立了白光外差干涉的数学模型,再根据数学模型提供的光强信号特性提出了整体系统设计方案,然后对测量方案的可行性进行了实验验证。最后针对多种误差对算法计算精度的影响进行了理论分析和数据对比。误差分析的结果表明:白光外差干涉测量技术提供更高的测量精度和更好的抗干扰性能,有效地降低了传统白光干涉测量对线性位移机构精度的严苛依赖,为光学自由曲面检测技术提供了更多的可选解决方案。
Abstract
In order to solve the problem that the displacement accuracy of linear displacement mechanism is too high in traditional white light interferometry, this paper proposes a full-field heterodyne white light interferometry. The technology mainly uses the white light interference signal with difference frequency as the light source to realize the high-precision detection of the coherent peak position under the conditions of large push step and low push precision. In this paper, the mathematical model of white light heterodyne interference is established firstly, and then the overall system design scheme is proposed according to the light intensity signal characteristics provided by the mathematical model. Then the feasibility of the measurement scheme is verified by experiments. At the end, theoretical analysis and data comparison are carried out for the influence of various errors on the calculation accuracy of the algorithm. The results of error analysis show that the white-light heterodyne interferometry technology provides higher measurement accuracy and better anti-interference performance, effectively reducing the strict dependence of traditional white light interferometry on the accuracy of linear displacement mechanism, and is an optical free-form surface detection technology. More solutions are available.
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Overview
Overview: In this paper, a measurement technique for full-field heterodyne white light interference is proposed. This technology uses white light interference signals with difference frequency to detect signal, aiming at reducing the high precision requirement of traditional white light interferometry for linear displacement mechanism. High-precision detection of coherent peak position under conditions of step size and low push-pull accuracy. Reducing the high precision requirements of the push-pull mechanism is of great significance for the development of white light interferometry. Firstly, the heterodyne signal is introduced on the basis of white light interferometry, and the mathematical model of white light heterodyne interference signal is established. According to the characteristics of light intensity signal and measurement target, a set of schemes for realizing white light heterodyne interference are proposed. The mathematical model of the difference interference signal has developed a special signal acquisition method, and the corresponding signal processing algorithm is proposed according to the signal acquisition method. The feasibility of the algorithm is verified by the simulation step measurement. Then the feasibility of the measurement scheme is verified by experiments. The experimental data analysis verifies that the system and algorithm principles are feasible. Finally, the effects of different scanning steps, scanning step precision and white noise of detector on the calculation accuracy of the algorithm are analyzed. The analysis results show that the full field white light heterodyne interferometry algorithm is more abundant than the traditional white light interferometry algorithm, and has higher measurement accuracy and stronger anti-interference. The step size is 50 nm and the step error is absolute. When the value is less than 5 nm, the calculation error in the case where the absolute value of the detector error is less than 1% of the amplitude can be stably maintained less than 0.1 nm, which can effectively reduce the dependence of the conventional white light interferometry on the high-precision linear displacement mechanism. Experiments have verified that this technique can achieve planar, spherical and aspherical surface measurements. This measurement technique can be used as an alternative to optical freeform measurement.
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参考文献
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