Tolerancing of centering of a reflective dual field-of-view optical system based on Alvarez-Principle. - In: Engineering for a changing world, (2023), 1.4.021, S. 1-15
A new dual state reflective optical relay system based on the Alvarez principle is proposed, which can be used for remote sensing applications. Using the solution found, two different object fields can be imaged using the same optical system. A Three-Mirror-Anastigmat telescope (TMA) is proposed with an intermediate image plane that incorporates a double reflective freeform subsystem as a relay system. By mechanically moving two freeform mirror substrates, this subsystem allows for a discrete change in the total focal length. A deep understanding of the effects of geometric deviations on the system is a crucial prerequisite for ensuring mechanical feasibility and stable optical imaging performance. For this reason, this article focuses on the method and results of tolerancing the subsystem.
https://doi.org/10.22032/dbt.58848
Scaling of a compliant mechanism for high-precision force measurement applications. - In: Engineering for a changing world, (2023), 1.4.013, S. 1-10
This paper is dedicated to the mechanical structure of a force transducer for the measurement of very small forces in the nanonewton range with highest resolution and lowest measurement uncertainty. To achieve this, a low stiffness in one direction of motion, but high stiffness in all other directions of motion is required. Existing solutions that meet the requirements are not suitable because of their overall dimensions. This results in a need for miniaturization. For this purpose, the scaling behavior of an existing monolithic compliant mechanism is investigated and it is verified which joint contour provides an optimal stiffness ratio. It is shown that the corner-filleted contour in general has lower bending stiffnesses, but also lower cross stiffnesses compared to the semi-circular contour. A nonlinear scaling effect for the ratio of bending stiffness and cross stiffness in corner-filleted contour offers optimization potential. Based on a simplified rigid body model, additionally, the miniaturization of the mechanism is optimized. The stiffness in the desired direction of motion is reduced by about 85% compared to a semi-circular contour. The result is promising for the further development of a miniaturized force transducer. The findings of this work contribute to the advancement of the measurement of low forces and offer new perspectives for future research in miniaturized force sensors.
https://doi.org/10.22032/dbt.58847
Development of a high precision electrostatic force balance for measuring quantity of dispensed fluid as a new calibration standard for the becquerel. - In: Engineering for a changing world, (2023), 1.3.097, S. 1-16
The 2019 redefinition of the kilogram not only changes the way mass is defined but also broadens the horizon for a direct realization of other standards. The True Becquerel project at the National Institute of Standards and Technology (NIST) is creating a new paradigm for realization and dissemination of radionuclide activity. Standard Reference Materials for radioactivity are supplied as aqueous solutions of specific radionuclides which are characterized by massic activity in the units becquerel per gram of solution, Bq/g. The new method requires measuring the mass of a few milligrams of dispensed radionuclide liquid. An electrostatic force balance is used, due to its suitability for a milligram mass range. The goal is to measure the mass of dispensed fluid of 1 mg to 5 mg with a relative uncertainty of less than 0.05 %. A description of the balance operation is presented. Results of preliminary measurements with a reference mass indicate relative standard deviations less than 0.5 % for tens of tests and differ 0.54 % or less from an independent measurement of the reference mass.
https://doi.org/10.22032/dbt.59188
Investigation of a novel monolithic stiffness-compensated mechanism for high-precision load cells. - In: Engineering for a changing world, (2023), 1.3.017, S. 1-12
Increasing demands in the fields of high-precision force measurement and weighing technology require an ever-higher measurement resolution, a larger measurement range, a lower measurement uncertainty, and traceability to a natural constant. Load cells using the compensation principle have the potential to fulfill these requirements. To enhance the measurement resolution and decrease the measurement uncertainty, the residual stiffness of the compliant mechanism in use needs to be compensated. Due to a lack of solutions in the state of the art, a novel monolithic stiffness-compensated mechanism for measurements according to the compensation principle was developed. Simulations show a stiffness reduction to 0.2%of the initial value, a theoretical force resolution of 31 pN, and applicability for any orientation in the gravity field. Experimental investigations on a prototype confirmed the existing potential. However, further optimization of the mechanism is required to negate the effects of manufacturing deviations.
https://doi.org/10.22032/dbt.58735
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.
https://doi.org/10.1364/AO.502846
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.
https://doi.org/10.1016/j.precisioneng.2023.06.014
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.
https://doi.org/10.5162/SMSI2023/B6.1
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