Fiber optic interferometric sensor based on mechanical oscillation
Fiber optic interferometric sensor based on mechanical oscillation
复制标题
基于机械振荡的光纤干涉传感器
DOI：
10.1117/12.827510
复制
发表时间：
2009
影响因子：
5.4
通讯作者：
J. Niehues
中科院分区：
文献类型：
--
作者：
P. Lehmann;M. Schulz;J. Niehues
对于高精度机械加工或光学工件的几何测量，通常需要纳米范围内的分辨率。这可以通过干涉原理来实现。此外，可以通过具有高数值孔径的光学系统来实现在陡峭侧面的测量。不幸的是，高NA总是伴随着小的焦深，导致测量范围非常有限。在这种情况下，可能的解决方案是所谓的深度扫描。我们实现了一个逐点测量的干涉传感器，并使用压电驱动弯曲梁的深度扫描。一个集成参考面的微型光纤探头安装在该梁的顶部。通过使用接近几百赫兹的谐振频率驱动的压电致动器，梁以几微米的振幅偏转。通过这种振荡，干涉仪的测量射线的光程长度被调制，而参考路径保持不变。这导致了干涉信号，该干涉信号随着光学探头和测量对象之间的平均距离的变化而显示出相位的特征变化。
For geometry measurement of high precision machined mechanical or optical workpieces a resolution in the nanometer range is generally required. This can be reached by interferometric principles. In addition, measurement at steep flanks can be achieved by optical systems with high numerical apertures. Unfortunately, a high NA is always accompanied by a small depth of focus leading to a very limited measuring range. A possible solution in this context is a so-called depth scan. We realized a pointwise measuring interferometric sensor and use a piezo driven bending beam for the depth scan. A micro-optical fiber probe with an integrated reference surface is mounted at the top of this beam. By use of a piezoelectric actuator driven close to the resonant frequency of several hundred Hertz the beam deflects with a few micrometers of amplitude. By this oscillation the optical path length of the measuring rays of the interferometer is modulated, while the reference path remains unchanged. This leads to an interference signal which shows characteristic changes in phase as the average distance between optical probe and measuring object changes.