Possibilities of error reductions of the frequency estimation by the multipoint interpolated discrete Fourier transform (IDFT) for rectangular and von Hann windows are described. An analysis is made to study the influence of the timedomain noise on the results of a DFT and interpolations. The quantization noise influence on the amplitude coefficients of DFT is in first approximation modeled by white noise in the time domain and Gaussian noise in the frequency domain. The noise influences on estimations are increased with the root of a number of the interpolation points, that is with apparent...
The national standard for length in Slovenia is materialised by gauge blocks 0,5 to 1000 mm. These gauge blocks are traceable to the primary standard and are used as a reference standard for calibrating standards from industry and calibration laboratories. The best measurement capability is not comparable with the capabilities of other European national laboratories having interferometric calibration systems but is covering the industrial needs at the moment. However, our aim is to improve measurement capability without involving interferometric system which would be too expensive for the...
In this paper, we describe a visual feedback system using a stereoscopic microscope. The system controls a micromanipulator so that a needle head may pierce a target as much length as desired. The tip position of the needle head and the target under the microscope are measured three dimensionally with two CCD cameras that are set to the eyepieces of the microscope. However, the visual feedback system has difficulties in detecting the tip position of the needle head within the target. We developed a method to predict the tip position of the needle head in the target. Before the needle head...
Microsystems are miniaturised technical components in dimensions of mm, which consist of mechanical and electronic or optic functions and functional elements. Microsystems are used as sensors and actuators in different applications for automobiles, medical techniques or peripheral computer equipment. They are manufactured in series or small series. Sensors, actuators and many technical microproducts require components with small dimensional form and surface tolerances in the µm range. If one includes the physical processes, precision starts to reach nano levels. The tolerances of...
Relative displacement measurement by use of absolute acceleration measurement was attempted. A micro-electronic accelerometer, working on the servo-accelerometer principle was tested for this application. The results of extended investigation indicate that this theoretically simple way of relative displacement measurement is not feasible in practice due to large errors introduced by doubleintegration of the accelerometer output signal corrupted by drift and noise.
The imaging results of a group of experiments concerned with imaging two ultraprecise fabricated samples composed of Cu- and Al-alloies as well as silicon coated with C-N ion-beams in 1 µm scan range, have been analysed and discussed. The sources of SPM (Scanning Probe Micoscope) artifacts and the affect factors of the SPM images are presented and investigated. It is concluded that so many scanning images looking like “atoms” topography structure obtained have been misunderstood in the world, because it is very difficult to correctly and properly in terpret so many kinds of SPM artifacts in...
This paper describes a measurement technique (submonolayer ellipsometry) that can be used for the measurement of very thin layers and submonolayers (monolayers that do not cover the whole surface of a substrate). Ellipsometry is a very old common known technique in form of Nullellipsometry, Rotating Polariser, Rotating Compensator and Rotating Analyser Ellipsometry for the measurement of thin films. But for the measurement of very thin films these techniques are not useful, because Rotating Analyser, Rotating Compensator, Rotating Polariser Ellipsometers are from theory and praxis not able...
The formation of the surface roughness during the machining of hardened steel, similar to the machining of “soft” materials, so far has been considered as a function of the cutting parameters (cutting speed, feed, cutting depth), the minimal chip thickness and the nose radius. Experimental results have not proved the theoretical calculations to be correct, and appeared to have a significant deviation. Actually the surface roughness is depending on the condition and roughness of the cutting edge to a great extent. Theoretical examinations can confirm our experience that a correlation occurs...
A panoramic holographic interferometer with the maximum angle aperture is proposed. The main element is a conic mirror with an apex angle 90° and coaxial with the cylindrical object. Near the object a cylindrical photoemulsion film is placed. Peculiarities of image and of interference picture restored by an unrolled twoexposured hologram are examined. Measurement methods of all displacement vector components of the external and internal surface points of the optically transparent shell are expounded. Sensitivity is equal in all surface points. Tomographical measurement methods of relative...
New packaging concepts are required for power electronic modules allowing to dissipate high loss power density levels at low operation temperatures. Best heat removal from a substrate is obtained using liquid coolants. However, in this way the heat transfer coefficient is limited by the Leidenfrost phenomenon. A promising attempt to improve the thermal transfer significantly is the development of silicon substrates structured with microwhiskers perpendicular to the surface. However, an industrial application of this new technology for heatspreaders in power electronic modules makes necessary...