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We discuss the possibility that the contours or details of images can be obtained by using the low-spatial-frequency or high-spatial-frequency parts of the reference beam in ghost imaging. The influence of the threshold selection which is used to divide the reference pattern into low-frequency and high-frequency parts is quite different. With the increase of the threshold, the signal-to-noise ratio (SNR) of low-frequency ghost imaging increases firstly and then decreases, while SNR of high-frequency ghost imaging decreases gradually. Under a suitable threshold, the results are compared with those by directly filtering ghost-image from the traditional ghost imaging. It is shown that better imaging quality can be obtained by using our scheme. To further improve imaging quality, the method of subtracting background before correlation calculation is also presented. [ABSTRACT FROM AUTHOR]

Abstract We report a 1 × N hybrid radio frequency (RF) photonic splitter with arbitrary phase shift and amplitude ratio using a dual-polarization dual-parallel Mach Zehnder modulator (DP-DPMZM). The DP-DPMZM is properly set to generate an orthogonally polarized single-sideband (SSB) modulated optical signal. By controlling a polarization controller (PC) and a polarizer (Pol.) that cascaded behind the modulator, an RF photonic splitter with arbitrary phase and amplitude ratio can be realized. Compared with previous reported works, the proposed RF splitter can be operated in a wide bandwidth since no optical or electrical filters are involved. The proposed scheme is theoretically analyzed and experimentally verified. [ABSTRACT FROM AUTHOR]

A new type of optical in-line holographic three-dimensional (3-D) video display system with omnidirectional viewing zones by using a center-symmetric multi-sideband filtering method is proposed. The frequency spectrum of the complex hologram is center-symmetrically divided into even numbers of multi-sidebands and partitioned into two groups by being alternately selected along the angular direction. One group corresponding to the conjugate image is filtered out in both of the digital-recording and optical-reconstruction processes with their specific filter masks. Then, from the other group, the real image, which can be viewed from almost all directions with a set of angularly-subdivided viewing zones, is reconstructed on the optical 4- f lens system without a conjugate image. Fourier-optical analysis and experiments with 3-D objects in motion confirm the feasibility of the proposed system. [ABSTRACT FROM AUTHOR]

Bessel illumination is an established method in optical imaging and manipulation to achieve an extended depth of field without compromising the lateral resolution. When broadband or multicolour imaging is required, wavelength-dependent changes in the radial profile of the Bessel illumination can complicate further image processing and analysis. We present a solution for engineering a multicolour Bessel beam that is easy to implement and promises to be particularly useful for broadband imaging applications. A phase-only spatial light modulator (SLM) in the image plane and an iterative Fourier Transformation algorithm (IFTA) are used to create an annular light distribution in the back focal plane of a lens. The 2D Fourier transformation of such a light ring yields a Bessel beam with a constant radial profile for different wavelength. [ABSTRACT FROM AUTHOR]

In this work, a low-pass plasmonic filter based on spoof surface plasmon polaritons (SSPPs) is reported by etching the two grounds of coplanar waveguide with periodic grooves. The cutoff frequency of the filter coincides with the asymptotic frequency of the SSPPs that are supported by the periodic grooves, which can be tuned by the depth of the grooves at will. In addition, a T-shaped groove is designed to increase the equivalent depth of the groove so as to realize the miniaturization of the proposed filter by decreasing the equivalent cutoff frequency of the SSPPs. Measured S-parameters of the two proposed low-pass plasmonic filters agree well with the simulated ones, which validates our ideas and designs. This simple low-pass plasmonic filter can find potential applications in plasmonic circuits and systems. [ABSTRACT FROM AUTHOR]

A quadratic polar coordinate transform technique is proposed to improve the demodulation accuracy of the circular carrier interferogram. Through the quadratic coordinate transform, the circular carrier interferogram is converted to the linear carrier interferogram with uniform spatial frequency, whose signal spectrum is significantly separated from the unwanted ones. Thus, the phase under test can be accurately retrieved by the conventional Fourier transform technique. Both the simulant and experimental results demonstrate that the proposed technique can be used for precise demodulation of the phase distribution of a circular carrier interferogram. [ABSTRACT FROM AUTHOR]

Abstract: To acquire phase projection information for moiré tomography, a new spatial phase-shifting lateral shearing interferometry is presented in this paper. The system is very simple and contains only three linear gratings and two filters. No wave plates or polarization elements are introduced. Moreover, via using a 4-f system, the optical path is greatly shortened and two complete spatial phase-shifted lateral shearing interferograms can be obtained simultaneously. A corresponding two-step phase-shifting algorithm is used for phase retrieval and the interferometry is used to extract the first-order partial derivative of the spherical wave. The results show that the proposed method is not only feasible but also has high accuracy. Propane flame phase information is measured by the optical system. Finally, error analysis of phase projection extracted by two-step spatial phase-shifting method is mathematically conducted. [Copyright &y& Elsevier]