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

本课题研究基于线形多距离传感器的精密部件的精确形状测量，该传感器动态跟踪测量对象的轮廓。在项目的第一阶段，我们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。测量对象被安置在一个精密的转台上。干涉线传感器在干涉仪的参考臂中使用光路长度的正弦调制和线扫描相机来记录干涉信号。结果是大约。每秒800,000个高度值。在转盘的单次旋转期间，传感器检测测量对象表面的圆环形状部分的几何形状。重复这样的测量不同的位置和拼接的个别重叠的圆形环段，产生完整的几何标本。在第二个项目阶段，测量系统扩展了基于光纤的照明，通过白光干涉测量法进行校准和扫描的绝对高度测量选项，以及传感器的电动倾角跟踪。此外，缝纫算法也得到了发展和不断改进。这些拼接算法有选择地利用重叠区域的冗余高度数据进行高精度的三维地形计算。在拟议的第三个项目阶段，基于线的形状测量系统将被多线相机扩展，这使得横向位移，同时测量高度值成为可能。这将产生新的评价可能性和测量策略，有待研究。例如，可以在传感器跟踪期间检测并考虑扫描方向的表面梯度，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测量不确定度的旋转表的摆动误差，并随后从地形测量值中消除其影响。该项目进一步打算扩大该系统的测量体积，以便可以测量直径达200毫米的样品。此外，这些传感器的动态跟踪也将被实现，这样自由曲面也可以被测量。在第三个项目阶段结束时，如果转盘作为在环形测量期间唯一移动的轴，不能达到最高精度要求，预计甚至可以实现更可靠的测量和更低的测量不确定性。这样做的目的是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.