Primary vibration calibration by laser interferometry ― requirements, problems and first experience with a new calibration system

摘要

Primary vibration calibration according to ISO 16063 can be carried out in several ways using different methods. Because of the wide frequency range and the possibility to calibrate sensitivity magnitude and phase, method 3 of part 21 of the international standard is mostly used in practice. Several requirements for components, system integration and control of the system must be met to achieve the goals of the standard and obtain low uncertainties in measurement and calibration. Illustrated by the CS18P primary calibration system of SPEKTRA, the main requirements, special problems and well-investigated solutions will be discussed. It will be shown that the all-digital vibrometer of Polytec plays an important part but, in addition to that, system integration and optimization of all components must be implemented with great care by calibration specialists. Our paper comes to the conclusion that, for primary calibration, high quality components alone will not be enough. It is necessary to integrate these components in an optimized system that takes into consideration all requirements and influences and so allows to reduce the uncertainties of the calibration procedure to the lowest possible values.