euspen’s 20 th International Conference & Exhibition, Geneva, CH, June 2020 www.euspen.eu Development of an all-optical dimensional measuring system Richard Leach 1,2 , Waiel Elmadih 1 , Samanta Piano 1 , Mohammed A. Isa 1 , Danny Sims-Waterhouse 1,2 , Nicholas Southon 1 , Wahyudin P. Syam 1 1 Manufacturing Metrology Team, University of Nottingham, UK 2 Taraz Metrology, Nottingham, UK richard.leach@nottingham.ac.uk Abstract We present the novel design of an all-optical dimensional measuring system (AODMS) for measuring the geometry and surface texture of small-scale components. The system is designed to operate in a cube of 100 mm sides, with micrometre or sub-micrometre measurement uncertainties. The AODMS includes a four-axis motion system for mounting and moving the sample to be measured, a photogrammetric system for coordinate measurement and motion system tracking, a combination of coherence scanning interferometry and focus variation microscopy for texture measurement and a metrology frame fabricated using additive manufactured lattice structures with internal resonating bandgaps for vibration isolation. The paper will discuss the development of the AODMS, the experimental realisation of the instrument and the first steps in its validation. Coordinate metrology, surface topography, information-rich metrology 1. Introduction To address the need for three-dimensional (3D) measurement of the geometry of complex milli- to micro-scale components, there have been a number of developments of tactile micro- coordinate measuring machines (CMMs) – see [1] for a recent review. However, the commercial success of such CMMs has been limited due to their delicate mechanics, complexity of use, contact nature and slow measurement speeds. To address these limitations, several optical surface topography measuring instruments have been equipped with multi-axis motion systems to allow them to act as CMMs (e.g. [2]), but for geometry measurement they require multiple stitching operations and can be slow. Optical probes have also been integrated with tactile CMM platforms (e.g. [3]) or robot arms (e.g. [4]), but these are usually for geometry measurement only and often have limitations in terms of object accessibility. In this paper, we present the novel design of an all-optical dimensional measuring system (AODMS) for measuring the geometry and surface texture of micro-scale components. The system is designed to operate in a cube of 100 mm sides, with micrometre or sub-micrometre measurement uncertainties. This new system is designed to be fast and produce dense point clouds; characteristics that are not shared with tactile instruments [1]. It is important to state up front that the AODMS is not designed to be a state-of-the-art coordinate measuring system and/or surface texture measuring instrument – rather it is a platform to demonstrate the concepts of “information-rich metrology” (IRM) [5]. When manufacturing a product, we have information about the product before we start manufacture. We usually have computer models, information about the materials, and we often know what to look out for in terms of defects. This “a priori” information can be used to enhance the measurement process by focusing on what exactly needs to be measured, so decreasing the time to do it. Most of the above information becomes available at product development and at manufacturing process planning, and we are asserting that such information may also bring benefit to metrology. Several examples of IRM will be investigated using the AODMS, but first, we need a highly stable platform with multi- scale sensing capabilities. This paper concerns the design and development of such a platform. 2. System design The core design principle of the AODMS is to combine two scales of optical measurement to create a system for measurements of the geometry and surface texture of small- scale components. Additively manufactured lattice structures are incorporated into the design to aid in vibration isolation, with the aim of improving the performance of the optical measurements. Figure 1 Computer render section view of the AODMS, with the central cube being the measurement volume possible with both texture and form sensors. The optical texture sensor (see Section 2.2) is mounted on an aluminium ring, which places the thermal centre close to the optical axis of the surface texture measurement. The ring also places all three photogrammetry cameras (see Section 2.1)