Oscillating microoptical fiber sensor for precision production measurement

在项目的第一阶段，针对所使用的元件和信号处理算法，构建了具有不同振荡光纤微探头的光学传感器，并对其进行了分析和优化。其结果是一种双波长干涉仪，其重复性测量的标准偏差低于1纳米。该系统在平面、倾斜和弯曲镜面反射表面上进行测量。在项目第二阶段现有部件和系统的基础上，应研究更高级的研究课题，以便能够评估新技术的能力。关键的方面涉及传感器数据速率的提高、工程表面的粗糙度测量、扩展测量范围直到达到绝对距离测量、微光学探头的改进，最后是通过动态探头跟踪测量三维地形。基于希尔伯特变换对测量的调相干扰信号进行扩展分析，目的是使传感器的数据速率提高到100 kHz。初步研究表明，使用波长范围从1300 nm到1550 nm的红外光，可以在Ra值为100纳米的工程表面上测量表面粗糙度。因此，需要对新型传感器在表面粗糙度测量中的适用性进行详细的研究。从文献中已知的方法允许将双波长干涉仪的测量范围扩展到超过合成波长的一半的限制。这些方法应在考虑到相位测量不确定性的新传感器的情况下使用。为了演示传感器的能力，应建立一个演示系统，包括两个横向扫描轴和一个精确的轮廓跟踪机构。这需要执行器信号和测量信号的电子同步，以实现尽可能好的测量精度。

During the first phase of the project optical sensors with different oscillating fiber optical microprobes were built, analyzed, and optimized with respect to the used components and signal processing algorithms. A result is a two wavelength interferometer which reaches a standard deviation of repeatability measurements below 1 nanometer. The system measures on plane, tilted, and curved specularly reflecting surfaces. Based on existing components and systems in the second phase of the project more advanced research topics shall be studied in order to be able to assess the capabilities of the novel technology. Crucial aspects are related to an enhancement of the data rate of the sensor, roughness measurement on engineered surfaces, extension of the measurement range until an absolute distance measurement is reached, improvement of the microoptical probes, and finally the measurement of 3D-topography via dynamic probe tracking. An extended analysis of the measured phase-modulated interference signals based on the Hilbert transformation aims at an enhanced data rate of the sensor of several 100 kHz. Preliminary investigations show that the use of infrared light of the wavelength range from 1300 nm to 1550 nm enables surface roughness measurements on engineered surfaces characterized by Ra values of several 100 nanometers. Therefore, the applicability of the new sensor to surface roughness measurement shall be studied in detail. Approaches known from literature allow an extension of the measurement range of a two wavelength interferometer beyond the limitation of half the synthetic wavelength. These approaches shall be used in context with the new sensor considering the uncertainty of phase measurement. In order to demonstrate the capabilities of the sensor a demonstration system comprising two lateral scan axes and a precise contour tracking mechanism shall be built. This requires an electronic synchronization of the actuator signal and the measured signals in order to achieve as good as possible measurement accuracy.