Shape measurement of precision components by use of a dynamically tracking interferometric line sensor

本项目研究的是基于线形多距离传感器的精密零件的精确形状测量，该传感器动态跟踪测量对象的轮廓。在该项目的第一阶段，提出了测量近似旋转对称光学表面的概念，并进行了实验验证。测量对象放置在精密转台上。干涉型线传感器利用干涉仪参考臂上光程长度的正弦调制和行扫描相机记录干涉信号。这导致了大约。每秒800,000个高度值。在转台旋转一周期间，传感器检测测量对象表面的圆形环形段的几何形状。对不同的径向位置重复这样的测量，并缝合各个重叠的环形环段，就得到了样品的完整几何形状。在第二个项目阶段，测量系统扩展了基于光纤的照明，通过白光干涉法进行校准和扫描的绝对高度测量选项，以及传感器的移动倾斜跟踪。此外，还开发了拼接算法，并对其进行了不断改进。该算法选择性地利用重叠区域的冗余高程数据来计算高精度的三维地形。在拟议的第三个项目阶段，线形测量系统将由一个多线相机扩展，该相机可以横向移动，同时测量高度值。这将导致需要调查的新的评估可能性和衡量策略。例如，可以在传感器跟踪期间检测和考虑扫描方向上的表面梯度，或者可以使用基于剪切算法的评估方法。此外，在测量过程中将记录目前限制可实现的测量不确定度的理论工作台的摆动误差，并随后从地形测量值中消除其影响。该项目还打算扩大该系统的测量体积，以便可以测量最大直径为200毫米的样品。此外，还将实现对传感器的实时跟踪，以便也可以测量自由曲面。在第三个项目阶段结束时，即使旋转工作台作为圆环测量过程中唯一移动的轴没有达到最高精度要求，也有望以更低的测量不确定度实现更可靠的测量。这意在为可能将测量系统转移到应用中提供最佳的前提条件，例如在转移项目的框架内。

This project deals with the accurate form measurement of precisioncomponents based on a line-shaped multi-distance sensor, which isdynamically tracked to the contour of a measuring object. During thefirst phase of the project the concept for the measurement ofapproximately rotationally symmetrical optical surfaces wasdeveloped and verified experimentally. The measuring object islocated on a precise rotary table. The interferometric line sensor usesa sinusoidal modulation of the optical path length in the reference armof the interferometer and a line scan camera to record theinterference signals. This results in approx. 800,000 height values persecond. During a single revolution of the rotary table, the sensordetects the geometry of a circular-ring-shaped segment of the surfaceof the measuring object. Repeating such measurements for differentradial positions and stitching of the individual overlapping circular ringsegments, yields the complete geometry of the specimen. During thesecond project phase, the measuring system was extended by a fiberbasedillumination, an absolute height measurement option by meansof white light interferometry for calibration and scanning, and themotorized inclination tracking of the sensor. In addition, stitchingalgorithms have been developed and successively improved. Thesestitching algorithms selectively utilize the redundant height data fromthe overlapping regions to calculate 3D topographies with highprecision. In the proposed third project phase, the line-based formmeasuring system is to be extended by a multi-line camera, whichallows laterally displaced, simultaneous measurement of heightvalues. This will result in new evaluation possibilities andmeasurement strategies which are to be investigated. For example,surface gradients in the scanning direction can be detected and takeninto account during sensor tracking, or evaluation methods based onshearing algorithms can be used. In addition, the wobble error of therotary table, which currently limits the achievable measurementuncertainty, will be recorded during the measuring process and itsinfluence will be subsequently eliminated from the topographymeasurement values. The project further intends to extend themeasuring volume of the system, so that specimens of up to 200 mmin diameter can be measured. In addition, an on-the-fly tracking of thesensor is to be implemented so that free-form surfaces can also bemeasured. At the end of the third project phase, it is expected thatconsiderably more reliable measurements with lower measurementuncertainty will be even possible if the rotary table, as the only axisthat is moved during a circular ring measurement, does not achievethe highest accuracy requirements. This is intended to provide optimalpreconditions for the possible transfer of the measuring system intoapplication, e.g. within the framework of a transfer project.