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We propose a novel, high-contrast imager called a polarization interferometric nulling coronagraph (PINC) for direct detection of extrasolar planets. The PINC uses achromatic half-wave plates (HWPs) installed in a fully symmetric beam combiner based on polarizing beam splitters. Jones calculus suggests that a stellar halo suppression level of 10 10 can be achieved at 5 [lambda]/D for a broad wavelength range from 1.6 to 2.2 [micro]m by using Fresnel-rhomb HWPs made of BK7. Laboratory experiments on the PINC used two laser light sources (wavelengths of [lambda] = 532 and 671nm), and we obtained a halo suppression level of approximately [10.sup.-6] at 5 [lambda]/D for both wavelengths. OCIS codes: 350.1260, 120.3180, 260.5430, 260.3160, 050.5080.

An improved illumination system is proposed for creating a temporally coherent and spatially incoherent extended source to be used for spatial coherence control and reconstruction of a coherent hologram. Taking into account the fact that a rotating ground glass does not behave as an ideal Lambertian diffuser, the new illumination system tailors the directivity of the scattered lights to direct the lights efficiently into an interferometer so that a spatial coherence function can be better controlled and detected with higher fidelity. Experimental results are presented that demonstrate improved performance of the proposed system. OCIS codes: 030.1640, 120.1088.

The influence of tilted surfaces on the measurement of shape by spatial coherence profilometry is investigated. Based on theoretical analysis and experimental results, the systematic measurement error caused by surface tilt is determined. The systematic measurement error depends not only on the tilt angle but also on the parameters of the experimental setup. The theoretical analysis and the experiments show the similarities and differences between spatial coherence profilometry and white-light interferometry. We also suggest the conditions to obtain correct measurements by use of spatial coherence profilometry. [c] 2009 Optical Society of America OCIS codes: 030.1640, 030.1670, 120.3180, 120.6650.

To attain deeper nulling for an extended incoherent star disk a scheme for an achromatic interfero-coronagraph, incorporating two common-path interferometers in tandem, is proposed. Analytical and numerical predictions of the performance, which are in reasonably good agreement, are presented. The predicted performance improvement, by using two interferometers in tandem, is demonstrated by a preliminary experiment. A star coronagraph based on the proposed technique has the possibility to reach a [10.sup.-10] achromatic nulling contrast for an almost [10.sup.-2] [lambda]/D effective source size. OCIS codes: 260.3160, 260.5430, 050.5080.

A three-dimensional common-path interferometer is proposed, which can achromatically null out an on-axis source while maintaining the detectability of an off-axis source. A geometric phase in the three-dimensional interferometer introduces an achromatic [pi]-phase shift to the light from the on-axis source, such that destructive interference nulls out the axial light at one of the ports of the interferometer. Light from the off-axis source, which is exempt from destructive interference, comes out from both ports with equal intensity. The common-path scheme makes the system highly immune to environmental disturbances. In the described experiment, a 6 x [10.sup.-6] peak-to-peak nulling contrast was obtained. OCIS codes: 260.3160, 260.5430, 050.5080.

The optical path difference (OPD) and amplitude of a sinusoidal wavelength scanning (SWS) are controlled with a double feedback control system in an interferometer, so that a ruler marking every wavelength and a ruler with scales smaller than a wavelength are generated. These two rulers enable us to measure an OPD longer than a wavelength. A liquid-crystal Fabry-Perot interferometer (LC-FPI) is adopted as a wavelength-scanning device, and double sinusoidal phase modulation is incorporated in the SWS interferometer. Because of a high resolution of the LC-FPI, the upper limit of the measurement range can be extended to 280 [micro]m by the use of the phase lock where the amplitude of the SWS is doubled in the feedback control. The ruler marking every wavelength is generated between 80 [micro]m and 280 [micro]m, and distances are measured with a high accuracy of the order of a nanometer in real time. OCIS codes: 120.3180, 120.3930, 120.5050, 120.5060, 230.3720.

To satisfy the increasing demand for extremely tight overlay accuracy in semiconductor manufacturing processes, all the measurement error factors in alignment systems and overlay measurement tools need be identified and eliminated. The principle of most alignment systems is based on image processing of target marks on the wafer under bright-field illumination. Although the phenomenon that the sensitivity to the alignment error varies with the step height (SH) of the mark has been known and used for evaluating the performance of the alignment optics, no investigation has been made into the origin and the physical mechanism of the phenomenon. We propose a simplified optical model that can account for the origin of the asymmetric image and clarify its relation to the SHs. The model is validated with simulation and experimental results. The improved performance of an alignment system using marks with optimally designed SHs is demonstrated. OCIS codes: 110.3960, 120.3940, 110.5220, 120.3930.

The phenomenon of Talbot self-image shift by changing the wavelength of the illuminating light is described and demonstrated experimentally. A periodic grating is illuminated by light with wavelengths [[lambda].sub.1] and [[lambda].sub.2] generated by two lasers, and the Talbot self-images are recorded along the longitudinal direction at individual wavelengths. The Talbot self-image shift due to the change in the wavelength of light is implemented for the measurement of the three-dimensional step height of a large discontinuous object without any phase ambiguity problem. Fourier-transform fringe analysis was used to determine the maximum contrast of the high-visibility bands for the measurement of the step height of the object. The main advantages of the proposed system are nonmechanical scanning, high stability because of its common path geometry, compactness, and a wide range of measurement as compared to interferometric three-dimensional profilers. OCIS codes: 110.6760, 120.2650, 120.2830, 120.5050.

To provide a theoretical background for the superiority of the signal-domain phase-only correlation (SDPOC) technique proposed here for microdisplacement measurement, we study the first- and the second-order statistical properties of the complex amplitude of an analytic signal of a white-light speckle pattern, under the assumption of a Gaussian random process, and give a formula for the autocorrelation function of the pseudophase associated with the complex analytic signal. Based on these results, we show mathematically that SDPOC has a performance advantage over conventional intensity-based correlation techniques.

As an alternative to the intensity correlation used in conventional speckle metrology, we propose a new technique for displacement observation that is based on spatial-signal-domain phase-only correlation and that makes use of the pseudophase of the complex analytic signal generated from a Hilbert-filtered speckle pattern. Experimental results are presented that demonstrate the validity and the advantage of the proposed signal-domain phase-only correlation technique over both the conventional intensity correlation technique and the spatial-frequency-domain phase-only correlation technique.

A novel angle-measurement technique based on fringe analysis for phase-measuring profilometry is proposed. A two-dimensional (2-D) angle between two mirror surfaces is determined by least-squares fitting of a plane to the 2-D distribution of the phase difference introduced by the 2-D tilt angle. To evaluate the performance of the proposed technique, numerical simulations that use the Fourier-transform technique and the phase-shift technique for fringe analysis were performed, and the results are compared. A 2-D angle-measurement interferometer based on a Mirau interference microscope was developed that demonstrated the validity of the proposed principle. It is shown by simulation and experiment that the proposed 2-D angle-measurement technique can achieve both a wide measurement range and a high angular resolution simultaneously. OCIS codes: 120.2650, 120.3940, 120.3180.

We fabricated and validated a coupled waveguide composed of striplines configured with a pair of closely aligned one-dimensional photonic crystals to develop a microwave component such as a demultiplexer with multiports. The system became opaque inside the photonic band gap region because of the absence of electromagnetic modes. Outside the photonic band gap region, the wave entered from the incident port is reflected at the coupled region despite of the geometric transmission configuration. A previous study suggested that this scattering characteristics must be interpreted as a result of coupling between two closely aligned transmission lines. In this study, we performed additional numerical analyses using the finite element method for the spatial distributions of electric fields, current, and charges to confirm the propagation patterns of modes and to elucidate the origin of the interesting transmission characteristics. We confirmed that this extraordinary propagation mechanism must be understood by the superposition effect of the photonic band structure and stripline coupling. Our findings provide the knowledge to design multiport microwave devises. [ABSTRACT FROM AUTHOR]

Techniques of unconventional holography, called holographic correloscopy, for imaging a three-dimensional (3-D) object through an opaque diffuser or via a scattering wall are reviewed. This paper is not intended to be a general overview. Instead, it will focus and shed light on less-known techniques termed coherence holography, photon-correlation holography, remote imaging digital holography, and dual-reference holography. This paper will introduce how they perform 3-D imaging through a diffuser or via a scattering wall with a thin but strongly scattering layer. [ABSTRACT FROM PUBLISHER]

Through its presentation of the recent and continuous developments in optical instrumentation, this Applied Optics feature celebrates the 400th anniversary of Galileo Galilei's telescope and the subsequent discoveries he made. OCIS codes: 350.1260, 350.6090, 220.4610, 120.4570.