9762 papers found
An optical differentiation phase measurement system using a modified multi-step bias-shifting method is proposed. The signal obtained by multi-step bias shifting is divided into two groups in this new method. The effectiveness of the new method was demonstrated using a computer simulation.
The aim of this paper is to present the first initiatives of the photometric group at Inmetro to analyze and test measurement procedures of lighting performance of roadways. At present, the evaluation for the average illuminance follows the brazilian standard ABNT-NBR-5101. The illuminance values measured in the field test are compared with calculated values, using the intensity distribution of the luminaires, which have been measured with a goniophotometer. Close agreement is found.
A fast optical roughness measuring device with a compact design is presented. The measuring principle is based on double scattering of coherent light. The measurement results in an integral statistical roughness value like Ra or Rq according to ISO 4287. It is valid for the illuminated surface area with diameters between 0.5 mm and 10 mm at a resolution of about 1 nm (Ra-value). A simulation model of the optical roughness measuring process based on the Huygens-Fresnel approximation was implemented. The simulation tool enables to investigate potential improvements of the measuring method...
The paper deals with problems of dynamic behaviour and shows especially how the development of microelectronics influences this field and how to teach this trends applying also heuristic methods and approximations. Using the results of information theory a new optimization criterion is introduced.
In this paper, we report on the recent development of a novel low coherence interferometry technique for the purpose of 3D-topography measurements. It combines the well established techniques of spectral-interferometry (SI) and chromatic-confocal microscopy (CCM). It allows for the detection of an object’s depth position, without the necessity of a mechanical axial-scan, and the measurement is performed in a so-called “single-shot” manner. Focusing the white-light with a microscope objective combined with a diffractive optical element leads to an expansion of the axial-range of the sensor...
The application of Fibre-Reinforced Plastics is important in many engineering areas, but vital for the aerospace industry. This work shows how inline metrology can contribute to a feasible production of composite parts. An inspection system based on a Machine Vision System will be presented as a key-component for the automatic construction of complex Preform structures.
We propose a super-resolution microscopy that employs standing evanescent light illumination and image reconstruction method with successive approximation. Samples are illuminated with standing evanescent light, which is formed and shifted into different positions on the interface of total internal reflection (TIR). Scattering light emitted from the illuminated samples is detected through far-field imaging optics. We assume two hypotheses of linearity and incoherence about the scattering light. Then we reconstruct the sample distribution from scattering images and standing evanescent light...
To detect particulate defects on patterned wafers of below 100 nm design rule, we proposed a new detection method using evanescent light illumination. To verify the feasibility of the method, we performed fundamental experiments. The results show that particle with a size of 170 nm on the patterned wafer surface with about 400 nm pitch is detected.
This article presents a proposal for the development of a Knowledge management system for the management of Metrologic knowledge. It was conceived to solve the problematic detected at some metrological organizations in México. It shows the revision of some information about HR problems, Knowledge management and Technology of education tendencies. The system is under development in the time this paper was written, however it is considered pertinent to present this information as a strategy that could be adopted by any organization concerned with metrology and on the other hand it expected to...
Least square linear regression is widely used in analytical chemistry. In practice a linear relationship between substance content and measured value still has been assumed based on the correlation coefficient criterion, although not recommended. Textbooks provide the necessary formulas for the fitting process, based on the assumption that there is no error in the independent variable. In practice the ordinary least squares (OLS) textbook procedure is used even when the previously stated assumptions are not strictly fulfilled. In this paper, how to validate the calibration function is dealt...