The teaching of metrology in undergraduate courses includes concepts such as traceability, calibration and uncertainty. This paper proposes a certain activity that students will have to realize in the Metrology Laboratory. The purpose of this activity is that students understand the contribution that the traceability chain has in the estimation of the uncertainty of a measurement. The activity should be realized in three stages. The first one consists of the construction of a mass measuring device. In the second stage, the pupil realizes the calibration of the device with two different patron mass kits. In the third stage, the student weighs different problem masses and informs the value of the measurand with an uncertainty statement, calculated with the information of his previous calibrations. Once the student has obtained different uncertainties of the same measurand, estimated with the same instrument, the instruments’ traceability relevance will be set.

In the research a possibility was studied how to reduce a number of repetitions of measurements when performing dissemination of 1 kg mass standard and at the same time maintain the level of confidence of the measurement results.
The method considered is designed for weighing schemes where a pair of support plates for weights is required to carry out comparisons of combinations of weights on comparators with automatic weight handler and the same pair of support plates is used for many of the compared weight combinations.
The results of analysis indicate to minor relation between the changes in mass differences of the compared weights and the changes in mass differences of the support plates. It can be seen that there is no influence on the mass of compared weights due to improper handling of the weights. The main reason for the deviations of the measurement results when using the support plates might be the performance of the comparator.

Calibrations of shock acceleration are industrially required from a view of human safety and product development. In NMIJ vibration group, a shock acceleration calibration machine (hereafter ‘calibration machine’) has been developed in response to much demand from Japanese industries, and can calibrate shock transducers in acceleration range from 200 m/s² to 5000 m/s². For primary calibration, accelerometer is calibrated by a combination of shock exciter and laser interferometer. In the shock exciter, shock acceleration is generated by rigid body collision between a hammer and an anvil. To avoid any disturbance motion, radial air bearing system is adapted to keep high stiffness in perpendicular directions to the collision. The hammer, supported by the air bearing, is accelerated by an air gun and collides with the anvil through a rubber pad. Thus, acceleration waveform of the anvil strongly depends on viscoelasticity of the rubber pad. Different hardness of the rubber pad is examined to realize various peak accelerations. As another significant issue, optimization of low-pass digital filter is necessary to obtain reliable acceleration waveforms. This manuscript reports not only a procedure of low-pass digital filtering but also cut-off frequency dependence of low-pass digital filter on peak acceleration.

The performance specifications of a shaker may be strongly affected by the load which it is driving. When using a shaker for calibration purposes, the mass and mass distribution of the device under test as well as its mounting configuration may deteriorate seriously the purity of the motion of the shaker armature along the desired axis. In this paper the authors present an attempt to reduce the magnitude of parasitic movements by an improved mounting configuration. Although the resulting motion is significantly improved, transverse, bending and rocking acceleration could not be diminished to less than 10 % as recommended by the ISO standard. In spite of this unsatisfactory large resulting parasitic motion, a reasonable calibration of a device under test is nevertheless possible when selecting carefully the axis of the reference laser vibrometer. We were able to validate this approach by a comparison with a calibration carried out on an alternative vibration exciter of inherently better quality (but considerable higher cost).

The laser vibrometer (LV) is a powerful non-contact transducer capable of accurately measuring point motion quantities by means of interferometric techniques. According to the requirements in standard ISO/IEC 17025, measurement traceability to the International System of Units (SI) is to be established through an unbroken chain of calibrations, linking measuring and testing equipment to the national or international measurement standards. At present, standard procedures specifying how to calibrate a laser vibrometer are still an open issue. As laser vibrometers are becoming more and more a standard measurement tool for the mechanical engineer, the establishment of standards and calibration procedures becomes more urgent. Otherwise, LVs can not be used in many applications such as a reference for the calibration of accelerometers by secondary laboratories. The vibration laboratory of INMETRO has two digital laser vibrometers and is developing a new calibration system to trace them back to the Brazilian national measurement standards. Basically, two alternative methods are applicable: primary calibration by laser interferometry, and secondary calibration by comparison to a reference transducer traceable to a national standard. This paper focuses on the primary calibration of laser vibrometers against a homodyne quadrature interferometric system. The system under development may be able to calibrate LVs with both analog and digital outputs. The theory of the method is briefly described. The scheme of the new experimental setup is presented and some experimental results obtained in a preliminary implementation are given.