Reflective dual field-of-view optical system based on the Alvarez principle. - In: Applied optics, ISSN 2155-3165, Bd. 62 (2023), 31, S. 8390-8401
A novel, to the best of our knowledge, dual-state reflective optical relay system based on the Alvarez system is proposed, which can be used for remote sensing applications. By keeping the image and pupil positions constant, it can be combined with a telescope to achieve two different magnifications. As a compact structure with only two moving parts, freeform optical mirrors and a nearly diffraction limited performance for the infrared wavelength 8 µm make it an attractive subsystem for space applications. Different design tradeoffs and the preferred layout properties are discussed in detail.
Manufacturing and static performance of porous aerostatic bearings. - In: Precision engineering, Bd. 84 (2023), S. 177-190
According to the common body of knowledge, aerostatic bearings invariably need narrow manufacturing tolerances to ensure maximal load capacity and high stiffness. This study experimentally investigates the manufacturing of porous material aerostatic bearings and the effect of manufacturing parameters on the performance properties of the bearings. During the study, samples were manufactured using different methods, and the geometrical and performance properties of each sample were inspected. The bearing performance measurement device developed during the study is introduced. The results present the dependence between manufacturing parameters and bearing properties under varying load and operating pressure conditions. The results clearly suggest that effect of bearing surface roughness on load capacity is small; meanwhile, surface planarity has a major impact on load capacity.
A Kibble balance as part of a quantum measurement institute in one room at NIST. - In: SMSI 2023 Conference - Sensor and Measurement Science International, (2023), S. 125-126
The new Kibble balance at the National Institute of Standards and Technology (NIST) is part of the Quantum Electro-Mechanical Metrology Suite (QEMMS). Two quantum standards are incorporated directly in the electrical circuit of the Kibble balance for the realization of the unit of mass. This eliminates the need for external calibration in the Kibble balance experiment. The targeted uncertainty is 2 μg on a 100 g mass and a range from 10 g to 200 g will be covered. We introduce the measurement concept of the QEMMS, show the current state of development and publish first measurements proving the performance of the newly designed balance mechanics.
Capacitance analysis of a shielded sphere-flat capacitor in a high precision electrostatic force balance. - In: Proceedings of the 23rd International Conference of the European Society for Precision Engineering and Nanotechnology, (2023), S. 449-452
Investigation of the sensitivity of a high-precision weighing cell to disturbances caused by the adjustment system. - In: Proceedings of the 23rd International Conference of the European Society for Precision Engineering and Nanotechnology, (2023), S. 223-224
Highly reproducible force application for a tool-changing system in nanofabrication machines. - In: Proceedings of the 23rd International Conference of the European Society for Precision Engineering and Nanotechnology, (2023), S. 73-74
Modeling of very thin flexure hinges considering surface topography. - In: Proceedings of the 23rd International Conference of the European Society for Precision Engineering and Nanotechnology, (2023), S. 71-72
Investigating the kinematic performance of a positioning device with subatomic resolution. - In: Proceedings of the 23rd International Conference of the European Society for Precision Engineering and Nanotechnology, (2023), S. 51-54
Novel method for determining the mechanical stiffness of weighing cells. - In: SMSI 2023 Conference - Sensor and Measurement Science International, (2023), S. 139-140
Weighing cells with electromagnetic force compensation are frequently used in precision balances and mass comparators. The kinematic structure is given by a compliant mechanism with concentrated compliances. Thin flexure hinges enable highly reproducible motion but limit the sensitivity to mass changes due to their rotational stiffness. To achieve the desired sensitivity, the stiffness of the mechanism must be further reduced by mechanical adjustments. To optimize the adjustment parameters, the initial stiffness of the mechanism needs to be characterized accurately. For this purpose, a novel self-testing method was developed. It allows accurate determination of the elastic stiffness of the weighing cell and the geometric stiffness caused by the masses of the linkages. The method uses static stiffness measurements in three orientations. The gravity vector must be orthogonal to the plane of motion to characterize the elastic stiffness. Determining the geometric stiffness requires the system to be in the working orientation. The upside-down orientation is used to confirm the results. This paper considers the novel method analytically and simulates using a rigid body model and the finite element method. The measurement of the stiffness of a weighing cell prototype is taken to validate the method.
Characterization and alignment of the flexure mechanism for the new Kibble balance at NIST. - In: ASPE Annual Meeting 2022, (2023), S. 80-84