1,721,012 research outputs found
Interframe intensity correlation matrix for self-calibration in phase-shifting interferometry
No full textA new method of estimating reference phase shifts in phase-shifting interferometry is proposed. The reference phase shifts are determined from a matrix that represents the interframe intensity correlation UIC) of phase-shifted interferograms. The root-mean-square error of intensity measurement is automatically obtained from the smallest eigenvalue of the IIC matrix. The proposed method requires only four interferograms, unlike others, and can extract phase shifts reliably even from interferograms without well-defined fringes, such as speckle patterns. In typical conditions, reference phase shifts and wave-front phases can be determined with an accuracy of lambda/6310 and lambda/150, respectively. The validity of the method is tested by comparing it with other methods in experiments and simulations. (c) 2005 Optical Society of AmericaX1111sciescopu
Resolution of Closely-Positioned Optical Vortices by Phase-Shifting Interferometry
No full textOptical vortices have been usually identified by using the characteristic fork-like structure in the interference pattern formed between a reference beam and the optical vortex field. It might, however, lead to misinterpretation of the property of vortices when the reference beam's phase difference between vortices is less than pi. We confirmed this experimentally and propose that closely positioned optical vortices can be resolved better by analyzing the phase map obtained through phase-shifting interferometry.X112sciescopuskc
Pixel-size-maintained image reconstruction of digital holograms on arbitrarily tilted planes by the angular spectrum method
No full textWe present an effective method for the pixel-size-maintained reconstruction of images on arbitrarily tilted planes in digital holography. The method is based on the plane wave expansion of the diffraction wave fields and the three-axis rotation of the wave vectors. The images on the tilted planes are reconstructed without loss of the frequency contents of the hologram and have the same pixel sizes. Our method shows good results in the extreme cases of large tilting angles and in the region closer than the paraxial case. The effectiveness of the method is demonstrated by both simulation and experiment. (C) 2008 Optical Society of America.X1124sciescopu
Rotation error correction by numerical focus adjustment in tomographic phase microscopy
No full textThe tomographic imaging technique in digital holography is improved and applied to the measurements of the refractive index distributions of two kinds of optical fiber. They are reconstructed from a set of quantitative phase maps obtained with a digital holographic method as the object is rotated for 180 deg. The errors of the phase maps caused by the defocusing due to the unwanted shift of the object relative to the rotation axis are corrected by numerical focus adjustment. The tomographic images of the fiber samples show the effectiveness of our method. (C) 2009 Society of Photo-Optical Instrumentation Engineers. [DOI: 10.1117/1.3242833]open1118sciescopu
Phase-contrast microscopy by in-line phase-shifting digital holography: shape measurement of a titanium pattern with nanometer axial resolution
No full textPrecision phase-contrast imaging has been achieved with in-line phase-shifting digital holographic microscopy. The complex amplitude of the object field on the charge-coupled device plane is measured by the phase-shifting method with a self-calibration algorithm, and the magnified object image is reconstructed with a plane wave expansion method. The phase fluctuation in the blank image without sample is 1.30 deg and the three-dimensional shape of a titanium phase test pattern is measured with an accuracy of 5.51 nm (corresponding to the phase resolution of 3.63 deg), which are better than those of off-axis systems. (c) 2007 Society of Photo-Optical Instrumentation Engineers.open11611sciescopu
Maximum-likelihood phase estimation in phase-shifting electronic speckle pattern interferometry and its comparison with least-squares estimation
No full textThe least-squares phase-fitting method, developed recently without any statistical justification, extracts an almost noiseless phase directly from the distribution of the intensities of phase-shifted speckle interference patterns [C. K. Hong et al., Opt. Lett. 20, 931 (1995)]. We present another method that can do the same by using the statistically well-established maximum-likelihood algorithm. Numerical simulations show that the precision of the maximum-likelihood estimate is better than that of the least-squares method by 19% and that its precision essentially achieves the one given by the Cramer-Rao lower bound. The limitations of the two methods subject to the phase variation within a fitting window are also studied. (C) 1997 Optical Society of America.X114sciescopu
Two-photon double-slit interference experiment
No full textWe report a two-photon double-slit interference experiment. Two correlated photons, generated by spontaneous parametric downconversion and traveling in different directions, are made to pass through a double slit in such a way that the path of one photon can be identified with that of the other photon. No single-photon interference pattern is observed even if the path is not actually identified, but a spatial interference pattern appears in the joint detection counting rates of the photon pairs. It can easily be shown that these nonlocal phenomena cannot be exhibited by any kind of classical field. (C) 1998 Optical Society of America [S0740-3224(98)01003-0].X1119sciescopu
Interaction-free measurement based on nonclassical fourth-order interference
No full textA new method of interaction-free measurement using a two-photon state is proposed. The scheme is an extension of Elitzur-Vaidman's original idea from a single-particle to a multiparticle case. It is also pointed out that the present proposal cannot be explained within the framework of classical wave theory.X116sciescopu
Optical section imaging of the tilted planes by illumination-angle-scanning digital interference holography
No full textA new method of optical imaging that can generate the section images of arbitrarily tilted planes has been developed from illumination-angle-scanning digital interference holography. A set of complex object fields are reconstructed from the holograms captured as the illumination angle is varied with uniform intervals. After the complex fields are modified with phase ramps that match the tilt (relative to the hologram plane) of a desired observation plane, the image of the object sliced along the tilted plane is obtained from their superposition. The axial resolution of a system employing this method is measured with a step height standard, and it is applied to the tomographic inspection of a microelectromechanical system. (c) 2010 Optical Society of America OCIS codes: 090.1995, 100.3010, 110.6880.X111sciescopu
Manifestation of complementarity in double-slit interference
No full textThe complementarity principle is experimentally demonstrated in the two-photon version of Young's double-slit arrangement. The concept of path distinguishability is applied to the extended Feynman paths by the use of half-wave plates and a polarizer. The experimental results can be clearly understood through the first principles of quantum mechanics.X116sciescopu
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