This paper compares the active and passive projector nonlinear gamma compensation methods for phase error reduction. The active method modifies fringe patterns before their projection to ensure sinusoidality; the passive method, in contrast, compensates for the phase error after capturing those distorted sinusoidal fringe patterns. Our study finds that the active method tends to provide more co...

In this research, an improved method for three-dimensional shape measurement by fringe projection is presented. The use of Fourier and Wavelet transform based analysis to extract the 3D information from the objects is proposed. The method requires a single image which contains a sinusoidal white light fringe pattern projected on it. This fringe pattern has a known spatial frequency and this inf...

In this paper we analyze the problems of fringe pattern estimation in optical stellar interferometry that are associated with optical path errors. Our rst nding is that an optimal fringe tracking system must track with path length errors of less than about one-eighth of the coherence length. The second is that if phase closure estimation is to be achieved at the lowest possible light levels, th...

Interference experiments with independent condensates provide a powerful tool for analyzing correlation functions. Scaling of the average fringe contrast with the system size is determined by the two-point correlation function and can be used to study the Luttinger liquid liquid behavior in one-dimensional systems and to observe the Kosterlitz-Thouless transition in two-dimensional quasicondens...

The influence of the in-plane displacement and double-aperture orientation on the slope fringe formation in double-shearing-aperture speckle interferometry is discussed in detail. The research results show that the two in-plane displacement components, one parallel to and the other perpendicular to the shearing direction, have an influence on the slope fringe formation and that the double-apert...

This paper presents a phase-shifting algorithm based on Hough transform for sinusoidal curves. Firstly, the background intensities of phase-shifting fringe patterns are removed by calculating their differences, thus we get purely sinusoidal intensity data for each pixel; and then we implement Hough transform to the intensity difference data of each pixel. As a result, the sinusoidal parameters,...

A method is described that enables the three-dimensional fields of a simple quadrupole mass filter (QMF) to be determined to a high accuracy. The technique produces accurate field values in the fringe field region as well as in the center of the filter. Using fields obtained typical filter performance is determined and shown to differ from that predicted when fringe fields are ignored. The comp...

Some commentators believe that slotting allowances enhance social welfare by providing retailers with an efficient way to allocate scarce retail shelf space. The claim is that, by offering their shelf space to the highest bidders, retailers act as agents for consumers and ensure that only the most socially desirable products obtain distribution. I show that this claim does not hold in a model i...

Fringe formation in the two-grating interferometer is analyzed in the presence of a small parallelism error between the diffraction gratings assumed in the direction of grating shear. Our analysis shows that with partially coherent illumination, fringe contrast in the interference plane is reduced in the presence of nonzero grating tilt with the effect proportional to the grating tilt angle and...

An adaptive approach is presented for noise reduction of optical fringe patterns using multivariate empirical mode decomposition. Adjacent rows and columns of patterns are treated as multichannel signals and are decomposed into multiscale components. Fringe patterns are reconstructed with less noise by simply thresholding coefficients in different scales. The proposed approach can better concen...