共查询到20条相似文献，搜索用时 109 毫秒
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回顾了光干涉与综合孔径技术发展的历史和现状，分析了国际上用于天文观测的一些著名地基和空基光干涉仪的技术特点，介绍了光干涉与综合孔径技术的发展，以及在光学综合孔径技术领域所发展的光纤与集成光学等新技术，简要介绍了近年来我国开展光干涉与综合孔径技术的进展情况。针对光干涉与综合孔径技术的发展前景和国内外技术发展趋势，发出了加快发展我国光干涉与综合孔径技术的呼吁。 相似文献
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郭红锋 《紫金山天文台台刊》2003,(1)
本文简单介绍了光干涉与综合孔径技术发展的历史、国际上用于天文观测的一些著名光干涉仪的技术特点和进展、以及近年来我国开展的与光干涉 ,综合孔径技术有关的工作 ,最后简要介绍了在光学综合孔径技术领域所发展的光纤与集成光学等新技术 相似文献
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本文简述了传统光学干涉仪的一种改良装置－多缝干涉仪，它可以提高可测星等，克服传统方法易受波长变化和双星亮度差异影响的缺点，保证测量精度。其可能应用领域是中、小尺寸望远镜以及下一代的望远镜的光学干涉观测。 相似文献
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恒星光学干涉仪中两光路的偏振特性是影响其干涉条纹对比度的主要因素之一。偏振效应包括由于反射产生的位相延迟和光的振动方向的旋转，并可能严重降低干涉条纹对比度，本文分析了偏振效应的产生原因和对干涉仪的影响，给出了三种典型的干涉仪光路布置，这些布置具有最小的条纹对比度损失。 相似文献
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恒星光学干涉仪中两光路的偏振特性是影响其干涉条纹对比度的主要因素之一．偏振效应包括由于反射产生的位相延迟和光的振动方向的旋转，并可能严重降低干涉条纹对比度．本文分析了偏抓效应的产生原因和对干涉仪的影响，给出了三种典型的干涉仪光路布置，这些布置具有最小的条纹对比度损失． 相似文献
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从基本原理出发,通过具体公式的推导,对恒星光学干涉仪应用于测量恒星位置和地球自转参数(ERP)进行了分析。结果表明:恒星位置可以不受基线矢量参数的影响而独立求解;但对于求解ERP,无论采取任何方法,解决基线稳定性问题是发挥干涉仪潜力的前提。 相似文献
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Klaus Maisinger M. P. Hobson A. N. Lasenby & Neil Turok 《Monthly notices of the Royal Astronomical Society》1998,297(2):531-535
Topological defect theories lead to non-Gaussian features on maps of fluctuations of the cosmic microwave background radiation (CMBR), which enable us to distinguish them from maps predicted by standard inflationary models. We have recently presented a maximum entropy method (MEM) which simultaneously deconvolves interferometer maps of CMBR fluctuations, and separates out foreground contaminants. By applying this method to simulated observations using a realistic ground-based interferometer, we demonstrate that it is possible to recover the prominent hotspots in the CMBR maps which delineate individual defects, even in the presence of a significant Galactic foreground. 相似文献
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A. T. Bajkova 《Astronomy Letters》2004,30(4):218-231
The problem of phaseless aperture synthesis is of current interest in phase-unstable VLBI with a small number of elements when either the use of closure phases is not possible (a two-element interferometer) or their quality and number are not enough for acceptable image reconstruction by standard adaptive calibration methods. Therefore, we discuss the problem of unique image reconstruction only from the spectrum magnitude of a source. We suggest an efficient method for phaseless VLBI mapping of compact extragalactic radio sources. This method is based on the reconstruction of the spectrum magnitude for a source on the entire UV plane from the measured visibility magnitude on a limited set of points and the reconstruction of the sought-for image of the source by Fienup's method from the spectrum magnitude reconstructed at the first stage. We present the results of our mapping of the extragalactic radio source 2200+420 using astrometric and geodetic observations on a global VLBI array. Particular attention is given to studying the capabilities of a two-element interferometer in connection with the putting into operation of a Russian-made radio interferometer based on Quasar RT-32 radio telescopes. 相似文献
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《Astroparticle Physics》2004,20(6):629-640
Operation of the central portion of Virgo as a simple 6 m Michelson interferometer has given the first demonstration of the possibility to control an interferometer suspended from Virgo full scale multistage seismic attenuators using information derived from the interferometer locking signal. A special role in the control is played by the first stage of these suspensions, an inverted pendulum: besides its seismic preisolation action, this stage has positioning dynamics of several mm, and it allows to exert a very low frequency control at the upper level of the suspension using the interferometer fringe signal. The application of this feedback to the top-stage of the suspension allows corrections of drifts, such as tidal ones, at a stage of the suspension where a large dynamic range in displacements is available, without introducing noise at the level of the mirror, resulting in a significant reduction of the lock keeping force applied directly on the mirror at the lowest stage of the attenuator. 相似文献
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闭合相位法是实现长基线恒星光干涉高分辨成像的重要技术手段之一,获得精确的闭合相位信息是进行光干涉图像重构的先决条件.提出一种基于精密光程差调制的时域干涉信号闭合相位检测方法,在3路干涉臂上进行非冗余精密光程调制,并通过多次干涉测量结合数据拟合的方法消除光程差调制中存在的正弦误差,使得光程调制的精度达到20 nm以内.引入高速探测器件提升时域干涉信号的采样频率,对探测器上获得的时域干涉信号进行傅立叶变换处理,获得3路干涉臂精确的闭合相位信息.室内实验结果表明,基于精密光程调制的时域信号闭合相位计算精度可以达到1/50波长以内. 相似文献
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Peter Hyland † Brent Follin Emory F. Bunn 《Monthly notices of the Royal Astronomical Society》2009,393(2):531-537
Cosmic microwave background (CMB) polarimetry has the potential to provide revolutionary advances in cosmology. Future experiments to detect the very weak B-mode signal in CMB polarization maps will require unprecedented sensitivity and control of systematic errors. Bolometric interferometry may provide a way to achieve these goals. In a bolometric interferometer (or other adding interferometer), phase shift sequences are applied to the inputs in order to recover the visibilities. Noise is minimized when the phase shift sequences corresponding to all visibilities are orthogonal. We present a systematic method for finding sequences that produce this orthogonality, approximately minimizing both the length of the time sequence and the number of discrete phase shift values required. When some baselines are geometrically equivalent, we can choose sequences that read out those baselines simultaneously, which has been shown to improve the signal-to-noise ratio. 相似文献
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R. Hanbury Brown 《Journal of Astrophysics and Astronomy》1984,5(1):19-30
The Chatterton Astronomy Department aims to apply interferometers with very high resolving power to optical astronomy. The
programme of the stellar intensity interferometer at Narrabri Observatory was completed in 1972 and since then the work has
been directed towards building a more sensitive instrument with higher resolving power. As a first step a much larger intensity
interferometer was designed but was not built because it was large, expensive and not as sensitive as desired. Efforts are
now being made to design a more sensitive and cheaper instrument. A version of Michelson’s stellar interferometer is being
built using modern techniques. It is hoped that it will reach stars of magnitude +8 and will work reliably in the presence
of atmospheric scintillation. It is expected to cost considerably less than an intensity interferometer of comparable performance.
The pilot model of this new instrument is almost complete and should be ready for test in 1984.
Text of an Academy Lecture delivered at the Raman Research Institute, Bangalore on January 27, 1984. 相似文献
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Mei Rong Hu Zhong-wen Xu Teng Sun Chang-sheng 《Chinese Astronomy and Astrophysics》2018,42(3):475-486
In stellar interferometers, the fast-steering mirror (FSM) is widely utilized to correct the wavefront tilt caused by the atmospheric turbulence and internal instrumental vibration, because of its high resolution and fast response frequency. In this study, the non-coplanar error between the FSM and the actuator deflection axis introduced by the manufacturing, assembly, and adjustment is analyzed systematically. Via a numerical method, the additional optical path difference (OPD) caused by the above factors is studied, and its effect on the fringe tracking accuracy of a stellar interferometer is also discussed. On the other hand, the starlight parallelism between the beams of two arms is one of the main factors for the loss of fringe visibility. By analyzing the influence of wavefront tilt caused by the atmospheric turbulence on fringe visibility, a simple and efficient real-time correction scheme of starlight parallelism is proposed based on a single array detector. The feasibility of this scheme is demonstrated by a laboratory experiment. The results show that after the correction of fast-steering mirror, the starlight parallelism meets preliminarily the requirement of a stellar interferometer on the wavefront tilt. 相似文献
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A simple image forming system using a multielement interferometer for obtaining rapid pictures of solar radio bursts is described. A dispersive transmission line is used to feed the elements in series through directional couplers. Truly instantaneous pictures of solar activity can be obtained by placing a number of narrow frequency filters at the end of the I. F. amplifier in the main receiver, located at one end of the array.The two dimensional extension of this principle is examined in some detail. Multibeaming in the two arrays of a crossed grating interferometer can be combined with fast phase-scanning in one of the arrays to produce rapid pencil beam pictures. If log-periodic antennas are used, observations can even be made at widely different frequencies simultaneously. For illustration, some important parameters for simultaneous observations at 60, 90 and 120 MHz are estimated for an interferometer assumed to be located at a latitude of 30° N. The main advantage of the proposed system is that high-resolution rapid pictures of radio bursts can be obtained simultaneously at a number of frequencies with modest effort. 相似文献
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Simon Albrecht Andreas Quirrenbach Robert N. Tubbs Ramon Vink 《Experimental Astronomy》2010,27(3):157-186
The combination of high spatial and spectral resolution in optical astronomy enables new observational approaches to many
open problems in stellar and circumstellar astrophysics. However, constructing a high-resolution spectrograph for an interferometer
is a costly and time-intensive undertaking. Our aim is to show that, by coupling existing high-resolution spectrographs to
existing interferometers, one could observe in the domain of high spectral and spatial resolution, and avoid the construction
of a new complex and expensive instrument. We investigate in this article the different challenges which arise from combining
an interferometer with a high-resolution spectrograph. The requirements for the different sub-systems are determined, with
special attention given to the problems of fringe tracking and dispersion. A concept study for the combination of the VLTI
(Very Large Telescope Interferometer) with UVES (UV-Visual Echelle Spectrograph) is carried out, and several other specific
instrument pairings are discussed. We show that the proposed combination of an interferometer with a high-resolution spectrograph
is indeed feasible with current technology, for a fraction of the cost of building a whole new spectrograph. The impact on
the existing instruments and their ongoing programs would be minimal. 相似文献
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A.J. Horton D.F. Buscher C.A. Haniff 《Monthly notices of the Royal Astronomical Society》2001,327(1):217-226
We present a numerical analysis of free-space propagation of the beams inside a long-baseline optical/infrared interferometer. Unlike the models of beam propagation used in most previous studies, our analysis incorporates the effects of atmospheric seeing on the wavefronts entering the interferometer. We derive results for the changes in throughput, coherence loss and fringe-detection signal-to-noise ratio arising from diffraction along the propagation path. Our results for conditions of moderate seeing show that although the flux throughput decreases with propagation distance for a given beam diameter, the fringe contrast increases at the same time. In this case it becomes possible for diffraction to increase the signal-to-noise ratio of the fringe measurements. Previous studies have only considered an arrangement where all the apertures in the beam-propagation system have the same diameter. If the light at the end of the propagation path is collected with a fixed size aperture, we find that in many cases the signal-to-noise ratio for fringe detection is maximized when the initial beam diameter is approximately 30 per cent smaller than the final collector diameter. We discuss the implications of our results in the context of future interferometer designs. 相似文献