Laser interferometry has been used for accelerometer calibration since the late sixties using counters for fringe counting and determination of zeroes at higher frequencies. As the digital techniques evolved during the eighties and nineties it became possible to make more sophisticated treatment of the complex output signals from the interferometer detectors. This was described in the revision of the previous standard ISO 5347-1 resulting in the new ISO 16063-11 in 1999. In this the so-called sine approximation method was introduced. As the input is known to be a sine, a least square fitting of the results calculated from the interferometer output gave good results. The fitting is basically a filtering at the known frequency. Therefore with the advanced high-resolution FFT analysers available today it is logical to use such analysers to do the filtering.
A system has been realised following these ideas. This will be described, and the evaluation of the system’s sensitivity to different imperfections, e.g. noise and gain differences in the interferometer output, will be reported. The evaluation is made using computer generated test signals and the technique can also be used to verify the system whenever needed.

We report about a novel optical method based on laser Doppler techniques for shape and vibration monitoring of fast rotating objects. Tip clearance and vibration measurements on a transonic centrifugal compressor preformed during operation at up to 50,000 rpm and 586 m/s blade tip velocity are presented. The results are in excellent agreement with those of capacitive probes and the achieved accuracy was about 20 µm.

The paper deals with the problem of the angular vibration sensor calibration. As a reference signal is produced by an incremental rotary encoder, which is a source of pulses. The pulse string determines the encoder rotation angle. The non-uniformity in the pulse distribution with respect to the rotation angle results in an error in determining the shaft rotation angle. The main topic of the paper is focused at the comparison of the encoder pair intended to employ for calibration of the Laser torsional vibration meter (BK 2523 type) based on the Doppler Effect. The method for evaluation of the rotation angle is based on the phase demodulation.

This talk summarizes statistical approaches to consistency analysis using key comparison data, including conventional mediated testing relative to the inverse variance weighted mean, extensions of this chi-squared methodology to accommodate finite degrees of freedom in the uncertainty claims, and a fully bilateral approach that avoids invocation of any key comparison reference value.

In this paper, a case-study of the THERMOWET measurement system control application is conducted and it’s software engineering aspects are described.