The wide-scale range of optical measurement technology and its exploration

High quality standards are a must for the majority of manufacturers in all industrial branches. Above all, optical principles have some exceptional properties that make them indispensable for use in all aspects of quality control. To them belong in particular the contactless and high speed interaction with the object under test, the largely free scalability of the dimension of the measuring tool, the high resolution of the measured data, the diversity of information channels transported by the light field, and the flexible adaptability of the measuring standard – the wavelength of light. However, to the outstanding unique selling points of the technology belong especially the extremely wide scale range of the objects that can be examined, their modalities and dimensions. But the trend of modern technologies shows a continued miniaturization of the critical features to be measured, an increasing complexity of the fabricated objects and their extended functionality. Consequently, the user is confronted with a number of serious challenges. Some of the biggest challenges that currently attract high attention in both technical and life sciences, are directed to exceeding the physical limits of optical resolution, to improve the precision of the measurement, and to be ready for the exploration of exotic materials. Therefore optical measurement methods are subject to constant improvement. The characteristics that give rise to improve the performance of the systems are obviously dependent on the purpose of the measurement and the object under test. But there are also general features that can be used to assess the performance of a measurement system. To them belong especially the spatial and temporal resolution, the area related resolution, the precision, the trueness of the delivered data, the robustness against external influences, the degree of automation, the process capability and the ability to work as close as possible to the process. After an explanation of our understanding of the wide scale range of optical metrology and a short excursion in its history, we describe several approaches to enhance the resolution of optical principles. Special attention is directed to improved methods of sensor fusion considering the full information content of the light field and the cooperation of various sensors that are activated in successive scales. Finally, we give an overview of the challenges with which the measurement technology is currently confronted and illustrate this on example of a new measurement machine.