Phase-modulation scatterometry is a metrology technique for determining, by means of a phase modulator as a key device, the parameters of gratings. The main source of error to be dealt with are the fluctuations of the phase-modulation amplitude. The grating zeroth-order reflectance modulated by the phase modulator is converted into a signal by the photodetector. The measurables are the direct term and the first two harmonics of the signal. For experimental

The Abelès method is a classical method for determining the refractive index of dielectric thin films. In this paper we examine the main features of the method in a formal manner, using closed-form equations, and we show that the method is ambiguous in certain yet unreported situations.

A current issue insufficiently addressed in nanometrology is the accurate characterization of calibrators with nanoscale features. Gratings are such calibrators and their pitch is one of the features that are used for calibration purposes. In this article the classic method of determining the gratings pitch from the measurement of the angular position of the refracted orders is used. To ensure traceability one has to relate the measurements to the

A new, fully statistical approach for regression analysis is presented and used for deriving the formula for the estimation error of the parameters of the fit and the associated joint confidence levels and limits. The key feature of the approach consists in two complementary parameterizations of the error space that are equivalent to a change of coordinates. This feature makes possible all the derivations and gives a marked statistical character

We adapted an experimental technique for characterizing the magnetotactic bacteria and simplified it by transferring the burden to literal and numerical computation, which is an advantageous trade-off. In a magnetic field the bacteria tend to orient their magnetic axes along the direction of the magnetic field, resulting in an anisotropic distribution of the orientation and, consequently, a significant change of the directional distribution of the

Equalization of histogram is used to process photographic digitized images composed mostly of pixels that are either very dark or very bright components. Equalization provides equal distribution of the number of pixels over the intensity range, which results in increased contrast and highlighted details. We apply here the histogram equalization to maximize the discernible number of fringes in a speckle pattern interferometry image, maximize the contrast

We describe a fast computational algorithm able to evaluate the Rayleigh-Sommerfeld diffraction formula, based on a special formulation of the convolution theorem and the fast Fourier transform. What is new in our approach compared to other algorithms is the use of a more general type of convolution with a scale parameter, which allows for independent sampling intervals in the input and output computation windows. Comparison between the calculations