Today, pressured air and gas leaks are typically detected using in-situ sensor technology. In this contribution the application of passive IR-thermography is proposed to permit remote leak detection by assessing the resulting temperature profile disturbance due to expansion of pressured gas. Remote measurements are advantageous as they are easier and safer to conduct. Scanning high-rise objects can be achieved using a ground-bound system without requiring complex climbing. In the paper a novel method for automated leak detection by feature extraction and pattern recognition is presented. This enables autonomous mobile robots with remote leak detection capability.

While other robots use in-situ measurements for gas leak detection and localization, we propose to apply remote sensing. It is easier and safer to conduct, permits rapid scans and is applicable to leak sources high up. An IR-optical sensor is used, exploiting spectral absorption effects of gases. Tailored leak detection and localization strategies are proposed. A simulation environment with a 3D model of the gas concentration field is used for developing and testing the detection and localization strategies. The system performance is demonstrated in a case study with a chemical plant.

The concept of gradation of materials leads to a continuous variation of mechanical properties by changing the microstructure. This can be obtained by suitable local thermal treatment promising the production of tailored mechanical properties.In this study, the dynamical behaviour in terms of damping and resonance frequency of gear shafts as system response to excitation is investigated. The shafts are made of CrNiMo-cementation steel. They will be used for evaluation if the functional gradation by local thermal treatment is accomplishable and effective with respect to the reduction of noise or vibration. Damping was received as the damping ratio estimated by the transfer function using the half-power bandwidth method. All measurements were carried out at room temperature.Micrographs were taken and showed the successful manipulation of the local microstructure of the shafts by heat treatment. A measurable influence on the damping ratio and resonance frequency was identified. (c) 2006 Elsevier Inc. All rights reserved.

A novel measuring system for optical distance sensing of solid targets is described. The system simply applies a noise-frequency-modulated laser diode for illuminating the target and an interferometer/photodetector device for coherent beam detection. This configuration is treated here as an optomechatronic correlator. The delay in travel time of the target beam in the interferometer yields a stochastically modulated electrical beat frequency in the photodetector output. Its mean frequency value is a measure for the target distance. Additionally to the required stochastic modulation of the injection current, the natural phase noise modulation of the laser diode also has to be taken into account. Theory delivers nonlinear measurement characteristics with strongly increased slope at the short-distance range. The experimental verification in a distance range up to 4 m shows a relative distance measurement error from 10/sup -3/ to 10/sup -2/(1/spl sigma/) for an averaging time range from 10 to 1 s. The system is potentially qualified for approach sensing in mechatronic devices like tool machinery and robotics.

To visualise laminar and turbulent flow patterns of gaseous or liquid fluids, the laser-light-sheet technique can be applied. The optically recorded flow images are useful for research and development of flow measuring and controlling devices. Instead of single high-power gas lasers or solid state lasers six monomode laser diodes emitting in the visible spectral range are applied. They are mounted in parallel and the individual radiation fields overlap to generate a more homogeneous intensity distribution with less coherence than with a single laser source. Therefore, disturbances due to speckle effects are reduced. The resulting light sheet has a total optical output power of 0.3W and a thickness of 0.7mm. The working distance amounts from 60mm up to 160mm with an operating area of 100×100mm2. Application examples of the internal flow characteristics of a gas–pressure regulator and high-speed gas flow diagnosis in a sonic Venturi nozzle are presented and compared with computational fluid dynamics (CFD) simulations.

We describe simultaneous determination of surface height profile and material distribution in the surface by imaging polarization detection. Starting from the single-beam case, the measurement principle based on the Stokes-Mueller formalism is deduced. This algorithm implies waviness detection of smooth as well as of rough surfaces. The basic concept of an imaging ellipsometer and its system configuration are discussed in the Stokes-Mueller formalism. Measuring the local slopes of the surface applying Fresnel's equations, the height image is deduced. Furthermore the imaging ellipsometer delivers the local complex refractive index from which the image of material distribution can be derived by a look-up table.

We present a coherent-optical measurement procedure for contactless distance sensing. The radiation source is a laser diode whose optical wavelength is randomly modulated about 3...12 pm (rms value) by noise modulation of the injection current at a bandwidth of up to 100 kHz. An interferometer serves as a coherent detector. The average beat frequency of the photodetector output is a measure for the absolute distance to the object. Combining the natural phase noise of the laser diode with an additional technical frequency-modulation process, sensitivity can be drastically improved, particularly in the short distance range (< 3 m). Due to the technical current modulation the coherent detection can be used well beyond the coherence length of the laser diode. For small target ranges the absolute distance resolution increases. This measurement behavior is advantageous for approach/docking applications, for example. The measurement procedure was verified experimentally. in a distance range up to 4 m.

Theory, experimental performance, and application of the noise-modulated interferometer are presented. This novel two-beam interferometer applies (1st) a laser diode source that is stochastically modulated in its frequency and (2nd) a common photodetector in the output arm followed by an averaging frequency counter. It is demonstrated that homodyne detecting of the two interferometer beams and counting the averaged beat frequency can be understood as a correlation process. By applying Horton's Anticorrelation' function to the signal processing channel of the noise-modulated interferometer, the range R <EQ 2 m of reflecting target is determined with high precision.

A laser interferometer with highly linear transfer characteristics for the undistorted measurement of mechanical vibrations is described. The linear transfer behavior is derived by a control loop which holds the optical phase difference within the interferometer on a constant value. As a phase-shifting element we use a linearized PZT actuator with integrated displacement sensor. With this interferometer harmonic and nonhannonic vibrations can be measured over 5 decades in the range of 1 Å to 25 μm. The frequency range extends from really DC to about 10 kHz (-3dB limiting frequency). Within the control loop we use primarily a proportional-integral controller with an integrated Wien-Robinson band-rejection filter which suppresses the resonance frequency of the PZT-actuator. This allows to increase the limiting frequency of the closed-loop interferometer by a factor 3 in contrast to a control loop without a rejection filter.