Deflectometry for technical surfaces (DOTS)

技术表面偏转测量 (DOTS)

• 批准号: 381609254
• 负责人: Professor Dr. Ralf Bernhard Bergmann
• 金额: --
• 依托单位: BIAS - Bremer Institut für Angewandte Strahltechnik GmbH
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2017
• 资助国家: 德国
• 起止时间: 2016-12-31 至 2020-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/381609254?language=en
• 关键词: Deflectometry; technical; surfaces; DOTS

Quality control requires, for many production processes, a fast, robust, non contact and high precision measurement technique for 3D form measurement. In view of these requirements, optical, non-interferometric techniques appear very suitable. The applicability and accuracy of these techniques, however, strongly depends on the surface properties of the objects under consideration. This is especially true for the surface roughness which may be very different for various technical surfaces. Individual technical objects often have to some extent optically smooth (mirror like or specular) areas as well as rough areas, making high-precision, reliable measurements extremely challenging.Phase Measuring Deflectometry (PMD) is a geometric-optical metrology technique primarily used for 3D form measurement of mainly specular objects. Systems based on PMD are in principle well suited for the characterization of technical surfaces, as they are smaller, cheaper and faster compared to tactile form measurement systems. However, the theoretical framework of PMD presupposes perfectly specular surfaces, neglecting object surface roughness and waviness. Technical object surfaces usually do not fulfil these demands and lead to additional measurement errors not adequately characterized up to now.Thus, the goal of this project is to develop realistic surface models for PMD measurements on technical surfaces that can predict the surface-related statistic and decrease systematic measurement errors. The sub-goals to be accomplished are: i) Modelling of the relationship between shape of the measurement object, geometry of the PMD setup and phase measurement errors, supported by test measurements of sample objects and simulation of measurements; ii) Modelling of the propagation of phase measurement errors into the derived quantities of surface forms, gradients and curvatures. The model used for achievement of sub-goal i) is the Bidirectional Reflectance Distribution Function. The approaches to this function are the Phong-procedure and Monte-Carlo methods. Sub-goal ii) is obtained by employing Least Squares Integration as well as Radial Basis Function Integration.With the models developed, systematic PMD measurement errors can be predicted and their reasons identified, and thus they can be corrected. Also the statistic uncertainties can be quantitatively determined for different types of object surfaces. This makes it possible for the first time for PMD form measurements to i) systematically adapt the PMD setup and the measurement procedures to the object surface to be measured; ii) increase the PMD measurement accuracy by correcting object surface-related systematic errors; and iii) calculate spatially resolved statistic measurement uncertainty maps related to the object surface.At the end of the project an optimized deflectometric measurement process suitable for technical surfaces shall be available in order to close a significant gap for industrial quality control.

对于许多生产过程来说，质量控制需要快速、稳健、非接触式和高精度的 3D 形状测量技术。鉴于这些要求，光学非干涉测量技术显得非常合适。然而，这些技术的适用性和准确性在很大程度上取决于所考虑的物体的表面特性。对于表面粗糙度来说尤其如此，表面粗糙度对于各种技术表面来说可能非常不同。单个技术对象通常具有一定程度的光学平滑（类似镜面或镜面）区域以及粗糙区域，这使得高精度、可靠的测量极具挑战性。相位测量偏转 (PMD) 是一种主要用于 3D 的几何光学计量技术主要是镜面物体的形状测量。基于 PMD 的系统原则上非常适合技术表面的表征，因为与触觉形状测量系统相比，它们更小、更便宜且更快。然而，PMD 的理论框架以完美的镜面表面为前提，忽略了物体表面的粗糙度和波纹度。技术物体表面通常不能满足这些要求，并导致迄今为止尚未充分表征的额外测量误差。因此，该项目的目标是开发用于技术表面上 PMD 测量的真实表面模型，该模型可以预测与表面相关的统计数据并减少系统测量误差。要实现的子目标是： i) 对测量对象的形状、PMD 装置的几何形状和相位测量误差之间的关系进行建模，并得到样本对象的测试测量和测量模拟的支持； ii) 对相位测量误差传播到表面形状、梯度和曲率的导出量进行建模。用于实现子目标i)的模型是双向反射分布函数。实现此函数的方法是 Phong 过程和蒙特卡罗方法。子目标ii)是通过采用最小二乘积分以及径向基函数积分来获得的。通过开发模型，可以预测系统PMD测量误差并识别其原因，从而可以对其进行校正。此外，可以定量确定不同类型物体表面的统计不确定性。这使得 PMD 形式测量第一次成为可能 i) 系统地调整 PMD 设置和测量程序以适应待测量的物体表面； ii) 通过纠正与物体表面相关的系统误差来提高 PMD 测量精度； iii) 计算与物体表面相关的空间分辨统计测量不确定度图。在项目结束时，应提供适合技术表面的优化偏转测量过程，以缩小工业质量控制的重大差距。