When a fluid flowing through an elastic vessel is subjected to a sudden change in pressure gradient, pressure pulses will propagate through the fluid. Velocity of these pulse waves (PWV) can be determined by simultaneous detection of wall distension on two separate points on the vessel wall, along its trajectory. PWV depends on wall stiffness, and under certain circumstances, wall stiffness can be calculated from the propagation velocity. In vivo detection of arterial PWV can have applications in cardiovascular risk management. Stiffness of large arteries has a very good predictive value for cardiovascular disease and overall mortality. This parameter can be estimated from arterial PWV. Current methods to measure arterial PWV suffer from several shortcomings. Laser Doppler vibrometry (LDV) can offer substantial advantages over existing techniques. In this work, we propose LDV as a noncontacting technique that allows measurement of wall distension on discrete locations. With two commercial vibrometers, we measured PWV in silicon tubes with different wall properties. Consequently, we determined PWV in living subjects. In a first step towards miniaturization, we used a custom built dual-beam LDV, with one laser source and one acousto-optic modulator (AOM) to evaluate PWV in elastic vessels. While measurements of PWV in living subjects with the dual-beam LDV are ongoing, we found that PWV as measured in elastic vessels agrees well with theoretically expected values, and measurement precision is better than 5%. Results of arterial PWV corresponded well with literature, but could not yet be validated.

This paper reports on the optical displacement sensors of a semi-optical system for measurements of roundness deviations of steel rings (~ 72.5 mm) during gas quenching. They are based on the extrinsic intensity modulation principle. The measurement system was developed within the scope of the Collaborative Research Centre SFB 570 of the German Research Foundation for investigation on the distortion of steel workpieces. Due to its capability for in-process measurements, this system also enables to compensate distortion effects. It is applied in a gas nozzle field specially designed for quenching steel rings symmetrically or asymmetrically with a broad variety of spatial temperature distributions. Before quenching, the ring has a starting temperature of 900 °C.
The measurement system has been built and successfully tested. It is able to measure the change of the roundness deviation of a hot ring during quenching. Before the calibration of the whole system, the sensors should be characterised and assessed.

We present a non-incremental interferometric measurement system for in-process monitoring of the dynamic behaviour of high-speed rotors, which is essential for improving safety and energy efficiency of motors and turbo machines, such as aircraft engines. The measurement system is based on the novel laser Doppler distance sensor which exhibits the unique feature that its measurement uncertainty of some microns is independent of the velocity of the device under test. This allows precise measurements of rotor deformations and blade vibrations even at high rotor speed. By aligning three sensors equally spaced by angles of 120° along the circumference of the rotor, dynamic deformations such as radial expansion and tumbling motions of the rotor can be measured simultaneously. Due to the robust fiberoptic sensor design, measurements can be carried out under vacuum condition and at high temperatures too.

Optical profilometry enables new dimensions of sensitivity in order to detect surface properties such as roughness and planeness of reflecting materials. For this purpose we developed an optical profilometer based on high-sensitivity heterodyne interferometry where a measurement beam is scanned over the surface of the device under test (DUT). With this measurement setup we are able to measure surfaces with approximately 5 nanometer accuracy. For scanning we developed a beam actuation system and a DUT actuation system with a lateral sensitivity of about 15µm.

At the Physikalisch-Technische Bundesanstalt (PTB), a new Deflectometric Flatness Reference (DFR) for measuring the topography of flat or slightly curved optical surfaces has recently been installed. With existing deflectometric procedures like the direct or difference mode, the spot size of the angle measuring system (autocollimator) is the limiting factor for the lateral resolution.
To reduce the spot size of the scanning beam, an additional measurement option, called Exact Autocollimation Deflectometric Scanning (EADS) is implemented. The surface under test is tilted at each measuring position to be perpendicular to the incoming light beam, and the tilt is measured by an additional autocollimator. The development of an angle measuring device with reduced spot size is explained. The development of the EADS system is detailed and the system will be compared with the classical deflectometric measurements.