D Wessel

Bio: D Wessel is an academic researcher from German National Metrology Institute. The author has contributed to research in topics: Microprobe & Coordinate-measuring machine. The author has an hindex of 1, co-authored 1 publications receiving 2 citations.

Integration of an isotropic microprobe and a microenvironment into a conventional CMM

Abstract: This paper describes the experimental verification of the novel IMT-PTB microprobe combined with a uniquely designed microenvironment. The microprobe consists of three silicon-based parallelograms stacked orthogonally, which leads to high isotropy. The probe tip deflections are detected in 3D with the help of piezoresistors placed in the parallelograms. The microenvironment facilitates and improves the measurement of workpieces with submillimeter features. The new microprobe and the microenvironment were integrated into a commercial coordinate measuring machine (CMM). To evaluate the microprobe performance, PTB produced and calibrated three reference objects: a cube, a sphere, and a microgear measurement standard. The differences between the calibration values and the measurement results obtained by the microprobe were in the sub-micrometer range. Furthermore, the microprobe was compared with the standard probing system of the gear measuring machine by measuring the reference objects with identical parameters. The results show the excellent performance of the micro probing system, thereby extending the capability of the CMM for high-precision measurements of complex workpieces at the microscale.

Surface-Sensing Principle of Microprobe System for Micro-Scale Coordinate Metrology: A Review

Abstract: Micro-coordinate measuring machines (micro-CMMs) for measuring microcomponents require a probe system with a probe tip diameter of several tens to several hundreds of micrometers. Scale effects work for such a small probe tip, i.e., the probe tip tends to stick on the measurement surface via surface adhesion forces. These surface adhesion forces significantly deteriorate probing resolution or repeatability. Therefore, to realize micro-CMMs, many researchers have proposed microprobe systems that use various surface-sensing principles compared with conventional CMM probes. In this review, the surface-sensing principles of microprobe systems were the focus, and the characteristics were reviewed. First, the proposed microprobe systems were summarized, and the probe performance trends were identified. Then, the individual microprobe system with different sensing principles was described to clarify the performance of each sensing principle. By comprehensively summarizing multiple types of probe systems and discussing their characteristics, this study contributed to identifying the performance limitations of the proposed micro-probe system. Accordingly, the future development of micro-CMMs probes is discussed.

Measurement Techniques for Three-Dimensional Metrology of High Aspect Ratio Internal Features—A Review

Abstract: Non-destructive measurements of high aspect ratio microscale features, especially those with internal geometries such as micro-holes, remain a challenging metrology problem that is increasing in difficulty due to the increasing requirement for more complexity and higher tolerances in such structures. Additionally, there is a growing use of functional surface texturing for improving characteristics such as heat transfer and wettability. As a result, measurement techniques capable of providing dimensional form and surface finish for these features are of intense interest. This review explores the state-of-the-art inspection methodologies compatible with high-aspect-ratio structures and their suitability for extracting three-dimensional surface data based on identified high-aspect ratio structure types. Here, the abilities, limitations, challenges, and future requirements for the practical implementation and acceptance of these measurement techniques are presented.

Development of a High-Function Fiber Stylus for Microstructure Measurement with Water-Repellent and Antistatic Coatings

Abstract: The precise measurement of microstructures and other micron-sized materials has garnered considerable interest in recent years. We have developed a measurement system that uses an etched small diameter optical fiber as a stylus to measure microstructures with low contact force. However, when the diameter of the stylus tip is less than a few tens of micrometers, the surface forces between the measured surface and the stylus tip become larger than the gravity of the stylus tip, causing the stylus tip to stick to the measured surface. This adhesion leads to an increase in measurement time and a decrease in measurement accuracy. In this study, we fabricated a high-function stylus with water-repellent and antistatic coatings applied to the stylus tip to reduce the adhesion between the stylus tip and measured surface due to surface forces, and conducted performance evaluation tests. As a result, the average separation distance was 13.8 µm when a fluorinated resin coating with a contact angle of 105° was used, confirming that the influence of liquid bridge forces could be reduced by approximately 78%. Additionally, when static elimination experiments were conducted by scanning the charged surface at a pitch of 0.5 µm using an antistatic coating stylus with a gold on the stylus surface, the average adsorption distance was 3.6 µm, confirming that the effect of electrostatic force could be reduced by 71%.