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Uniaxial crystal interferometer: Principles and forecasted applications to imaging astrometry
Optics Express
Abstract
We propose a new approach to imaging astrometry, the uniaxial crystal interferometer (UCI). It uses the extremely sensitive dependence of the polarization phase change on the incident angle in uniaxial crystals. This is further combined with very sensitive polarization measurements. The polarization-coding is used for a fine-scale angle determination, and is simultaneously combined with a crude measurement through a standard telescope. Further, achromatic anamorphic prisms will amplify five to tenfold the resolution which is estimated to reach the scale ratio of large interferometers. Because the fine angular information is superimposed on the light at an early stage the optical system tolerances are relieved to the level of a standard low-weight optical imaging system. We also suggest solutions to make the system achromatic. Overall the system may cover sky segments of the order of fractions of a degree square and reach a resolution of tens of microas, even for faint stars.
... For example, chromatic effects on plate retarders and their impact on astronomic applications have been deeply studied by Clarke [8,9]. Moreover, astronomical observations also require angledependent measurements [10]. Nowadays, there is an increasing tendency to large numerical aperture [11], and variable-angle applications that claim theoretical support in order to analyze their experimental results [12][13][14][15][16][17]. ...
A study on the influence of multiple reflections on the transmission coefficients of uniaxial plane–parallel plates is presented. Two representative models are analyzed: one that considers only the first transmission, and a rigorous one, taking into account the multiple reflections within the plate. Modules, phases, and the interference between $p$ p and $s$ s transmitted fields are evaluated in a wide range of angles of incidence by means of three emblematic examples that illustrate the effects of thickness, birefringence, and optical axis orientation. For simplicity, whereas the optical axis can form an arbitrary angle with the interface, it is restricted to the plane of incidence. A complete theoretical framework is provided along with general reference guidelines derived from numerical examples.
... 13. Multiple-prism arrays, in their various forms, are applicable to optical instrumentation, such as spectrometers[38], and even in astronomical instrumentation[42]. ...
Optics originally developed for tunable organic dye lasers have found applications in other areas of optics, laser optics, and quantum optics. Here, the salient aspects of the physics related to the cavity linewidth equation and the effects of intracavity beam expansion and intracavity dispersion on this equation are reviewed. Additionally, the generalized multiple-prism dispersion equation is applied to direct-vision prisms, also known as Amici prisms, to calculate dispersion configurations of practical interest. Then, the higher derivatives of the multiple-prism dispersion equation applicable to laser pulse compression are considered. From this perspective, a new compact and generalized equation for higher-order phase derivatives is introduced for the first time. Furthermore, it is shown how the N-slit interferometric equation, derived from quantum principles using Dirac's notation, gives rise to generalized versions of the diffraction grating equation and the law of refraction. The nexus between the N-slit interferometric equation and the cavity linewidth equation is also illustrated. Finally, various optical and quantum optical applications that have benefited from these developments are highlighted.
With rapid progress of Product Lifecycle Management (PLM) in manufacturing industry, automatic generation of inspection planning of product and the integration with other activities in product lifecycle play important roles in quality control. But the techniques for these purposes are laggard comparing with techniques of CAD/CAM. Therefore, an automatic inspection planning system for Coordinate Measuring Machine (CMM) was developed to improve the automatization of measuring based on the integration of inspection system in PLM. Feature information representation is achieved based on a PLM canter database; measuring strategy is optimized through the integration of multi-sensors; reasonable number and distribution of inspection points are calculated and designed with the guidance of statistic theory and a synthesis distribution algorithm; a collision avoidance method is proposed to generate non-collision inspection path with high efficiency. Information mapping is performed between Neutral Interchange Files (NIFs), such as STEP, DML, DMIS, XML, etc., to realize information integration with other activities in the product lifecycle like design, manufacturing and inspection execution, etc. Simulation was carried out to demonstrate the feasibility of the proposed system. As a result, the inspection process is becoming simpler and good result can be got based on the integration in PLM.
An exact, and explicit, expression for the second derivative of the generalized multiple-prism angular dispersion is provided. This corresponds to the third derivative of the generalized exit angle with respect to the refractive index (∇
n
3
φ
2,m
). Higher derivatives, in abstract notation, are also given. The generalized equations are presented in a format applicable to practical prismatic configurations utilized in laser pulse compression schemes in the femtosecond domain. Exact values, as a function of the refractive index, are given for the first, second, and third angular derivatives for compensating double-prism and four-prism configurations of practical interest.
C 3 Po is a concept for a novel array detector concept that is optimized for highly sensitive and precise differential imaging such as needed for astrophysical polarimetry. Chopping between two or more independent image states (such as four linearly independent polarization states) can be performed at speeds in the kHz domain to provide virtually simultaneous images without the need to read out the array at kHz frame rates. This allows the technology to be applied to large arrays with precise, slow readouts. All independent image planes are observed with the same physical pixel on the detector, which renders normalized differences between image planes insensitive to the gain of individual pixels. The detector concept has 100% geometrical fill factor and a quantum efficiency approaching unity. The technology can be applied to silicon to cover the 200-1100 nm wavelength range, and to infrared-sensitive materials such as HgCdTe or InSb for the 1-20 µm wavelength range. While the detector concept has a wide range of potential applications outside of astronomy, we focus here on its application to polarimetric observations of the Sun.
Growth of KDP-type crystals on the point seed made possible to accelerate growth rates from traditional 1 mm/day up to 50 mm/day. This acceleration gave base to a development of the rapid growth technique for production of single crystals with the linear sizes up to 90 cm to obtain plates for laser radiation conversion in world-largest lasers. Scientific bases and technological principles of the method are considered in this review.
The accurate measurement of the position of celestial objects is a fundamental step for several astrophysical investigations. For ground based instruments, the atmosphere is considered the basic limiting factor; in space, the knowledge of the instrumental parameters and/or of their stability define the performance limits, but CCD cameras operated in time delay integration may take advantage of their operating mode to reduce significantly the calibration problem. We implemented a low-cost laboratory experiment aimed at assessing the precision achievable in the location determination with a CCD camera, by evaluating the measurement repeatability throughout a set of images of a simulated stellar field. Our experiment provides an initial location dispersion of the order of 1/100 of the CCD pixel, with clear evidence of dominant common mode effects. After removing such terms with straightforward numerical procedures, we achieve a final location precision of 1/700 pixel on individual images, or 1/1300 pixel on co-added images. The scaling of precision with target magnitude is in quite good agreement with theoretical expectations. The initial common mode systematics appear to be induced by the thermal control of the CCD camera head, which degrades the structural stability. In actual implementations, such problems can be greatly reduced by proper design. Finally, our results show that residual effects, which could hamper the final astrometric accuracy, can be calibrated out with simple procedures.
By a combination of quarter-wave plates made of different birefringent materials it is possible to produce achromatic quarter-wave plates whose degree of achromatism is dependant on the dispersions of birefringence and on the thicknesses of the individual quarter-wave plates. These waveplates are widely used in optical instrumentation and the residual errors associated with these devices can be very important in high resolution spectro-polarimetry measurements. The misalignment of optic axis in a double crystal waveplate is one of the main source of error and leads to elliptical eigenpolarization modes in the retarder and the oscillation of its orientation according to the wavelength. This paper will discuss, first, how the characteristics of a quartz-MgF2 quarter-wave plate is affected by such a misalignment. A correlation with the experiment is then achieved in order to highlight the interest of taking a possible tilt error into consideration when doing polarimetric measurements.
Two completely independent systematic approaches for designing algorithms are presented. One approach uses recursion rules to generate a new algorithm from an old one, only with an insensitivity to more error sources. The other approach uses a least-squares method to optimize the noise performance of an algorithm while constraining it to a desired set of properties. These properties might include insensitivity to detector nonlinearities as high as a certain power, insensitivity to linearly varying laser power, and insensitivity to some order to the piezoelectric transducer voltage ramp with the wrong slope. A noise figure of merit that is valid for any algorithm is also derived. This is crucial for evaluating algorithms and is what is maximized in the least-squares method. This noise figure of merit is a certain average over the phase because in general the noise sensitivity depends on it. It is valid for both quantization noise and photon noise. The equations that must be satisfied for an algorithm to be insensitive to various error sources are derived. A multivariate Taylor-series expansion in the distortions is used, and the time-varying background and signal amplitudes are expanded in Taylor series in time. Many new algorithms and families of algorithms are derived.
The Nova and Beamlet Lasers were used to simulate the beam propagation conditions that will be encountered during the National Ignition Facility operation. Perturbation theory predicts that there is a 5 mm scale length propagation mode that experiences large nonlinear power growth. This mode was observed in the tests. Further tests have confirmed that this mode can be suppressed with improved spatial filtering.
We extend the analysis of Trebino (Appl. Opt. 24, Apr. 15, 1985) of single-material achromatic prism beam expanders to include two-material devices and practical expanders consisting entirely of commercially available 45-45-90 prisms. We show that sacrificing simultaneous achromaticity and thermal stability allows the construction of two-material prism beam expanders with only one of these two properties, but having significantly greater transmission than a similar-magnification single-material device. Finally, a numerical optimization routine yields optimal incidence angles for two-, three-, and four-prism single-material achromatic prism beam expanders. In general, we find that the "up-up-...-up-down" configuration is optimal in nearly all practical cases.
The Cambridge Optical Aperture Synthesis Telescope, COAST, is a four-telescope array for high resolution imaging using measurements of complex visibilities and closure phases. This paper describes what its component parts are and why.
At present, multiple-prism arrays play an important and pervasive role in laser optics. From intracavity beam expansion to pulse compression these integrated optical elements have given a new and expanded meaning to the word prism. In this article we offer a pedagogical introduction to the physics and mathematics of practical multiple-prism arrays.
Large size crystals of KH2PO4 (KDP) were grown by adopting rapid growth technique from point seeds in a 1500-liter crystallizer which is used to grow KDP crystals by conventional method. The grown KDP crystal size can reach to 310 × 310 × 320 mm3 and the average growth rate was 8mm/day. The optic properties of the rapidly grown KDP crystals were characterized comparing with the KDP crystals grown by the traditional temperature reduction method. We found it that the optical quality of the KDP crystals we grown rapidly are not significantly different from those of KDP crystals grown by traditional method. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
Conoscopic holography is an incoherent holographic technique based on the properties of crystal optics. More precisely, for each point of the object, the interference pattern between the ordinary and the extraordinary rays is presented. The pattern is a Gabor-zone-lens pattern, with a scale parameter that is a function of the distance of the point. The superposition of the Gabor zone lens from each point of the object is the hologram, which contains information on the shape of the object through the scale-parameter dependence of each point is presented. I present a simplified version of the theory of conoscopic holography. The point-spread function and the transfer function of the conoscopic system are presented by using simple arguments, and the conoscopic hologram is defined. The basic schemes for reconstruction, i.e., retrieving, optically or numerically, this three-dimensional information about the object from the recorded hologram, are presented. Finally, the resolution of the system is quantified.
The design of the NIF incorporates a type I/type II third harmonic generator to convert the 1.053-micrometers fundamental wavelength of the laser amplifier to a wavelength of 0.351 micrometers for target irradiation. To understand and control the tolerances in the converter design, we have developed a comprehensive error budget that accounts for effects that are known to influence conversion efficiency, including variations in amplitude and phase of the incident laser pulse, temporal bandwidth of the incident laser pulse, crystal surface figure and bulk non-uniformities, angular alignment errors, Fresnel losses, polarization errors and crystal temperature variations. The error budget provides specifications for the detailed design of the NIF final optics assembly and the fabrication of optical components. Validation is accomplished through both modeling and measurement, including full-scale Beamlet tests of a 37-cm aperture frequency converter in a NIF prototype final optics cell. The prototype cell incorporates full-perimeter clamping to support the crystals, and resides in a vacuum environment as per the NIF design.
A new, advanced and breakthrough technology has been developed for hot slab on-line surface inspection and installed in Aceralia (Spain). This innovative inspection system, integrating novel Conoscopic Holography, CCD cameras, a complex mechanical system and intelligent tools, operates in the real environment of a continuous casting facility, allows on-line hot slab surface inspection of 100 % of the production, detecting cracks -without removing the surface scale- and inclusions (peeling a narrow strip on the surface).
The laser driver for the National Ignition Facility will be a departure from previous inertial confinement fusion laser architecture of a master oscillator single pass power amplifier (MOPA) design. The laser will use multi-segment Nd:Glass amplifiers in a multipass cavity arrangement, which can be assembled into compact and cost effective arrays to deliver the required multi- megajoule energy to target. A single beam physics prototype, the Beamlet, has been in operation for over two years and has demonstrated the feasibility of this architecture. We present a short review of Beamlet`s performance and limitations based on beam quality both at its fundamental and frequency converted wavelengths of 1.053 and 0.351 {mu}m.
An account is presented of the Fine Guidance Sensor (FGS) which
furnishes guidance and astrometry in the HST, giving attention to its
interferometric design and its astrometric performance capabilities, the
astrometric observing modes and software commands used in their
implementation, and expected HST states with regard to line-of-sight
jigger, drift, and guidance mode during a given observation. FGS
operational modes discussed encompass support-system module control,
search, coarse track, fine lock, line-of-sight scan, and stop. In
astrometric measurements, relative positional accuracies of the order of
0.003 arcsec are achievable; precise parallaxes, detection thresholds
for planetary companions of nearby stars, and kinematic
characterizations of star clusters will be facilitated thereby.
In space astrometry one seeks to determine positions, parallaxes and proper motions of stars to within 50 prad. The proposed GAIA mission is based on a rotating instrument made up of two telescopes set at a large base angle to each other and scanning the same great circle in the sky. Since the intended performances impose very strict stability requirements, a sophisticated metrological system is needed, whose actual implementation requires an integrated design of telescopes and laser interferometers. This paper examines the response of the instrument to small perturbations, special emphasis being placed on the location of star images. In order to exploit laser interferometry as much as possible, the original design was reconsidered, the base-angle implementation was improved, the number of degrees of freedom was reduced and the critical parameters were factorized. Although the present paper considers only the original proposal, in which each telescope was designed as a Fizeau interferometer, the results can be readily extended to other configurations.
Optical astrometry of quasars and active galaxies can provide key information on the spatial distribution and variability of emission in compact nuclei. The Space Interferometry Mission (SIM PlanetQuest) will have the sensitivity to measure a significant number of quasar positions at the microarcsecond level. SIM will be very sensitive to astrometric shifts for objects as faint as V = 19. A variety of AGN phenomena are expected to be visible to SIM on these scales, including time and spectral dependence in position offsets between accretion disk and jet emission. These represent unique data on the spatial distribution and time dependence of quasar emission. It will also probe the use of quasar nuclei as fundamental astrometric references. Comparisons between the time-dependent optical photocenter position and VLBI radio images will provide further insight into the jet emission mechanism. Observations will be tailored to each specific target and science question. SIM will be able to distinguish spatially between jet and accretion disk emission; and it can observe the cores of galaxies potentially harboring binary supermassive black holes resulting from mergers.
An interferometric astrometric mission, aiming at accuracies at around the10 microarcsec level, was recommended as a high priority concept within thenew ESA Horizon 2000+ scientific programme. The original outline concept forsuch a mission, GAIA, presented its general feasibility but did not addressmany questions of implementation or optimisation. Another concept of aninterferometer for a scanning astrometric satellite is presented. It containsa simpler optical telescope and a more efficient detector system. The designutilizes the full resolution of all light in the dispersed fringes of aFizeau interferometer. A preliminary optimization of the satellite indicatesthat two telescope units with a baseline of 100 cm will achieve a precisionof 3, 8, 22, 68, 302 microarcsec for parallaxes of stars with V = 12, 14, 16, 18, 20 mag, respectively, from a 5 year mission. Simultaneousspectrophotometry of the entire spectrum of each star will be obtained with aresolution corresponding to intermediate band photometry. The expectedprecision of this photometry is about 0.003 mag for V = 16. The performance is good in crowded fields, at least up to one star per 5 arcsec2. A Hipparcos-type beam combiner of 150 cm width is placed in front of atelescope with 4 square apertures of 50 cm. The assumed focal length is f = 60 m and the field 0.5 degree diameter. The detector consists of CCDs used for time delayed integration (drift-scan.)
Recent instrumental developments in imaging polarimetry allow array detectors to reach a polarimetric sensitivity of 1 10–4 of the intensity. New instrumental effects appear at these levels of sensitivity and generate spurious polarization signals with amplitudes of up to 5 10–4. Here I discuss these effects and present methods to avoid them. Polarized spectra with an rms noise of 6 10–6 may then be obtained. Furthermore a method is brought to the reader's attention that allows polarization measurements at the 1 10–4 level with regular array detectors, e.g. in the near-infrared.
Space-based interferometers dedicated to wide-angle astrometry would dramatically increase the accuracy of angular measurements fundamental to a wide range of astrophysical problems. The proposed Global Astrometric Interferometer for Astrophysics (GAIA), a continuously rotating instrument comprising two or three interferometers, will reach the $5-20\,\mu$as level on more than 35 million objects. The necessary wide field-of-view for such a precision could be obtained with a Fizeau interferometer. We designed and modelled a 2.6 m baseline interferometer with two 40 cm apertures, and overall dimensions compatible with the size of the Ariane V payload shroud. It has a ~ 1 degree diffraction limited field-of-view. The response of the optical system to small perturbations on each optical element is given in terms of fringe visibility, which is shown to depend mainly on sub-aperture spot separation. The robustness of the design to thermal, mechanical and manufacturing errors is discussed.
One of the ESA candidate cornerstone missions is dedicated to wide-angle astrometry and aims at dramatically increasing the accuracy of astrometric measurements and the limiting magnitude with respect to Hipparcos (ESA Symposium, Venice, 1997). This mission was initially designated by the acronym GAIA (Global Astrometric Interferometer for Astrophysics) and featured several Fizeau interferometers. One important drawback of the original configuration proposed by Lindegren & Perryman (1996) was the confusion effect. This effect, which is a superposition of the light coming from different objects, is due to recording the fringe signal in the exit pupil plane of the instrument, necessary to relax the pixel size in the considered configuration. In order to overcome the confusion effect while retaining the original Fizeau interferometer concept, we present an optical configuration allowing direct fringe detection, i.e. in the image plane. It features focal length of 30 m inducing technologically feasible pixel size in the bandwidth of interest, and meets the condition to fit the Ariane V launcher fairing.
GAIA is a preliminary concept for an astrometric mission, recently recommended within the context of ESA's `Horizon 2000 Plus' long-term scientific programme. In its present form, the experiment is estimated to lead to positions, proper motions, and parallaxes of some 50 million objects, down to about $V=15$ mag, with an accuracy better than 10 microarcsec, along with multi-colour multi-epoch photometry of each object. The scientific case for such a mission is dramatic: distances and kinematical motions for tens of millions of objects, throughout our Galaxy, would be obtained—the expected accuracy is such that direct (trigonometric) distance estimates to the galactic centre would be accurate to 10%, with transverse motions accurate to about 1 km s$^{-1}$ at 20 kpc. As `by-products', the global measurements would yield unprecedented information on the space-time metric ($\gamma$ to a precision of about 1 part in $10^6$ or better, close to values which might distinguish currently competing theories of gravity), angular diameters of hundreds of stars, and a vast body of information on double and multiple systems. Perhaps the most dramatic of these subsidiary goals would be the possibility of screening some $100\,000$ stars within 100 pc for periodic photocentric motions, which would provide the most powerful and systematic method of detecting possible planetary companions proposed to date.
In this paper we present an holographic system based on the properties of optical propagation in birefrigent media. We have called it conoscopic after the conoscopic figures which are obtained when a spherical wave propagating through a birefrigent crystal, is observed through crossed polarizers. The idea can be summarized by saying that we replace the object and reference beams of coherent holography by the ordinary and extraordinary beams propagating in birefrigent media, two beams that are naturally coherent one with the other.
We report results from a test exploring the long- and short-term astrometric stability of Hubble Space Telescope Fine Guidance Sensor (FGS) #3. A test field was observed 40 times over 522 days to determine the precision and accuracy of FGS astrometry and to measure the character and magnitude of possible secular scale changes. We examine the astrometric data and the associated guide-star data to determine random errors. These data are also explored to find sources of systematic error. After correcting for some systematic effects we obtain a precision of 0.002 arcsec (2 mas) per observation (RSS of x and y). This is relative astrometry within a central 2.5 arcmin FGS field of view for any orientation. We find that the scale varies over time and confirm the sense of the trend with independent data. From the 40 observation sets we produce a catalog of an astrometry test field containing eight stars whose relative positions are known to an average 0.7 and 0.9 mas in x and y. One reference star has a relative parallax of 3.1 plus or minus 0.5 mas. Finally, we report that eleven observation sets acquired over 387 days produce parallaxes and relative positions with 1-mas precision.
Efficient frequency doubling and tripling are critical to the successful operation of inertial confinement fusion laser systems such as the National Ignition Facility currently being constructed at the Lawrence Livermore National Laboratory and the Omega laser at the Laboratory for Laser Energetics. High-frequency conversion efficiency is strongly dependent on attainment of the phase-matching condition. In an ideal converter crystal, one can obtain the phase-matching condition throughout by angle tuning or temperature tuning of the crystal as a whole. In real crystals, imperfections in the crystal structure prohibit the attainment of phase matching at all locations in the crystal. We have modeled frequency doubling and tripling with a quantitative measure of this departure from phase matching in real crystals. This measure is obtained from interferometry of KDP and KD*P crystals at two orthogonal light polarizations.
Several astrometric space interferometry mission projects (e.g. GAIA, FAME, DIVA) for scanning the sky in a similar fashion as Hipparcos are currently being discussed. Their raw detector signals will be dispersed interferometer fringes. This new type of signal will be directly recorded by CCD mosaics in drift-scan mode in the focal plane of Fizeau interferometers. The astrometric measurement, i.e. the determination of the one-dimensional relative position of the fringe pattern, perpendicular to the fringes (i.e. in the direction of the sky scan), and the extraction of the spectro-photometric information contained in the direction of the dispersion of the fringes (i.e. perpendicular to the sky scan) need a complex reduction technique. We report on the simulation of polychromatic dispersed fringe patterns of stars with different spectra taken from spectrophotometric libraries using the presently envisaged parameters of the DIVA instrument. The stellar signal was combined with expected da...
Producing National Ignition Facility (NIF)-quality beams on the Nova and Beamlet Lasers, Fusion technology 30 (C) 2005 OSA8 August OPTICS EXPRESS 6310 # 6814 - $15.00 USReceived 10
- C Widmayer
Widmayer, C., et al., Producing National Ignition Facility (NIF)-quality beams on the Nova and Beamlet Lasers, Fusion technology 30, 464-470 (1996). (C) 2005 OSA8 August 2005 / Vol. 13, No. 16 / OPTICS EXPRESS 6310 # 6814 - $15.00 USReceived 10 March 2005; revised 1 August 2005; accepted 2 August 2005 r16. Zaitseva, N. and L. Carman, Rapid growth of KDP-type crystals, Progress in crystal growth and charcterization of materials 43, 1-118 (2001).