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，质量控制需要快速、稳健、非接触和高精度的三维形状测量技术。鉴于这些要求，光学的、非干涉测量的技术显得非常合适。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对象的表面特性。这对于表面粗糙度尤其如此，其对于各种技术表面可能非常不同。单个技术对象通常具有一定程度的光学光滑（镜面或镜面反射）区域以及粗糙区域，这使得高精度、可靠的测量极具挑战性。相位测量偏折术（PMD）是一种几何光学计量技术，主要用于镜面反射对象的3D形状测量。基于PMD的系统原则上非常适合技术表面的表征，因为与触觉形式测量系统相比，它们更小，更便宜，更快。然而，偏振模色散的理论框架的前提是完美的镜面，忽略了物体表面的粗糙度和波度。技术物体表面通常不能满足这些要求，并导致额外的测量误差没有充分表征到现在为止，因此，本项目的目标是开发现实的表面模型PMD测量技术表面，可以预测表面相关的统计和减少系统的测量误差。要完成的子目标是：i）通过样品对象的测试测量和测量模拟来支持测量对象的形状、PMD设置的几何形状和相位测量误差之间的关系的建模; ii）相位测量误差到表面形状、梯度和曲率的导出量的传播的建模。用于实现子目标i）的模型是双向反射分布函数。该函数的求解方法有Phong法和蒙特-卡罗法。子目标（ii）是利用最小二乘积分和径向基函数积分的方法来实现的，利用所建立的模型，可以预测PMD测量系统的误差，找出产生误差的原因，并进行修正。此外，统计不确定度可以定量地确定为不同类型的物体表面。这使得PMD形状测量第一次能够i）系统地使PMD设置和测量过程适应待测量的物体表面; ii）通过校正物体表面相关的系统误差来提高PMD测量精度;以及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，应提供适用于技术表面的材料，以弥补工业质量控制的重大差距。