The role of the liquid-crystal layer in the phase-shifting shearing interferometer that was proposed by Griffin [Opt. Lett. 26, 140 (2001)] is analyzed. An extra voltage-dependent phase difference is produced when the phase retarder is oriented at an angle from the optical axis of the laser beam such that the interferogram will not repeat itself after a 2pi phase change of the liquid-crystal re...

We report on phase-shifted holographic interferogram demodulation by singular-value decomposition. Numerical processing of optically acquired interferograms over several modulation periods was performed in two steps: (1) rendering of off-axis complex-valued holograms by Fresnel transformation of the interferograms; and (2) eigenvalue spectrum assessment of the lag-covariance matrix of hologram ...

Quadriwave lateral shearing interferometry (QLSI) is a quantitative phase imaging technique based on the use of diffraction grating placed in front camera. This creates wire-mesh-like image, called an interferogram, that postprocessed to retrieve both intensity and profiles incoming light beam. Invented 90s, QLSI has been used numerous applications, e.g., laser beam characterization, lens metro...

When using quadrature signals in radio channels, flat and selective fading, multipath reception, intersymbol interference, jitter occur. In addition to the need accurately estimate value of phase difference at current previous clock intervals, a critical factor receiving demodulating such is accuracy measuring amplitude their samples. signals, an approach possible, basis which measure values in...

Atmospheric effects are among the primary error sources affecting accuracy of interferometric synthetic aperture radar (InSAR). The topography-dependent atmospheric effect is particularly noteworthy in reservoir areas for landslide monitoring utilizing InSAR, which must be effectively corrected to complete InSAR high-accuracy measurement. This paper proposed a correction method based on Multi-L...

The temperature and wind in the middle upper atmosphere can be obtained by recording Doppler shift broadening of airglow emission, which is reflected interference ring from a ground-based Fabry–Perot interferometer (FPI) system. FPI observations are highly susceptible to weather external environment, seriously affect signal-to-noise ratio (SNR) interferograms. An SNR significantly increase erro...

-This paper proposes a new technique for noise reduction applied to interferometric phase images. It involves a non-linear filtering system that not only eliminates noise in interferometric phase images, but also re-introduces detail information to the phase image. To implement the filtering system, a modified pivoting median filter with adaptive window size dependent on coherence is firstly us...

Conventional techniques approach Phase Unwrapping (PU) as an optimization problem, where figures of merit like the total branch-cut length, the number of cuts, etc, is to be minimized. They disregard the properties of the field to be unwrapped: the topography, i.e. the DEM, projected in the SAR reference. The purpose of the paper is to fill in this gap by providing statistics of the “fringe map...

We describe a simple and low-cost technique for resolving the complex conjugate ambiguity in Fourier domain optical coherence tomography (OCT) that is applicable to many swept source OCT (SSOCT) systems. First, we review the principles of coherence revival, wherein an interferometer illuminated by an external cavity tunable laser (ECTL) exhibits interference fringes when the two arms of the int...

Fourier domain optical coherence tomography (FD-OCT) is an interferometric imaging technique that allows imaging to depths of a few mm in scattering biological tissues with high resolution of the order of 1-10 μm. However, the usefulness of FD-OCT is limited by background and autocorrelation interference terms that reduce the sensitivity and by phase ambiguity that halves the useful imaging dep...