Automatic high resolution measurement set-up for calibrating precise line scales

Abstract

This paper presents a high resolution measurement set-up developed for calibrating precise line scales with measurement uncertainty of less than 0.1 µm over a total length of 500 mm. The system integrates a numerically controlled multi-axis stage, a laser interferometer, and a vision system for detecting line position. The measurement and the analysis processes are completely automated in order to minimize manual labour during the calibration process, but also increase the calibration accuracy. Increasing calibration accuracy leads up to better quality of industrial measurements which is required by modern precision industry. When designing this set-up, special attention was paid to the alignment of the measurement object in the measurement direction, considering the focus of the camera. The aim of this alignment was to reduce Abbe errors in 2 axes to negligible level. In addition, all uncertainty contributions have been determined and evaluated by performing extended experiments in specific measurement conditions. These contributions are presented in the uncertainty budget. The metrological capabilities of the presented measurement set-up were verified by some practical test measurements. Selected results of these measurements are presented in the article. This set-up will primarily improve a standard base for calibration of optical measuring devices. The use of the optical standards in the industry is constantly growing. Indirect users of the results of this research will be all manufacturers of precise products such as automotive and other industries.

Analysis of Laser Interferometer Measurement Uncertainty by Simulating Error Sources

“…2 b) can be corrected by applying angle measurements performed with laser interferometry or with an electronic level in fix points, e.g., in the zero position and in the end point of the measurement path. With highly precise positioning of a video probe system along a long measurement path, 10 m for instance, this type of error can contribute up to few μm; while in short precise measurements, even random errors of few-ten nm caused by uncontrolled mechanical changes along the axis, can contribute essentially to the total measurement uncertainty [1,8].…”

“…Measurement accuracy of these systems generally exceeds the requirements of the manufacturing tolerances, while used for monitoring advanced precise manufacturing technologies such as automotive industry, either for direct workpiece geometry measurements or for calibrating very accurate measuring instruments. In all cases, an accuracy analysis of the total measurement performance is needed [1]. Furthermore, the measurement systems shall be ready for fully automated integration into advanced manufacturing systems by enabling direct transformation of measurement data including calibration results into global information systems [2].…”

Metrological set-up for Calibrating 1D Line Scales with Sub-Micrometre Precision

“…2. The system integrates a numerically controlled multi-axis stage, a laser interferometer, and a vision system for detecting line position [11]. …”

Influence of Intracavity Power on Frequency Characteristics of Iodine-Stabilized He-Ne Laser

“…Such an iodine-stabilized He-Ne laser, named MIRS1, was used at the Laboratory for Production Measurements at the Faculty of Mechanical Engineering, University of Maribor (a nationally designated metrology institute of EURAMET), for the calibration of He-Ne lasers that are used for laboratory and industrial interferometry [2]. Inside the laboratory traceability chain, a secondary He-Ne laser interferometer, calibrated by MIRS1, is for instance used for calibrating the precise line scales, which are the most common measurement standards for assuring industrial traceability of optical measuring equipment, such as microscopes, profile projectors and digital vision systems [3].…”