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Active control of focal length and beam deflection in a metallic nano-slit array lens with multiple sources  [PDF]
Arif E. Cetin,Kaan Guven,Ozgur E. Mustecaplioglu
Physics , 2009, DOI: 10.1364/OL.35.001980
Abstract: We propose a surface plasmon-polariton based nano-rod array lens structure that incorporates two additional lateral input channels, with the ability to control the focal length and the deflection of the transmitted beam through the lens actively by the intensity of the channel sources. We demonstrate by numerical simulations that, applying the sources with the same intensity can change the focal point and the beam waist, whereas unequal intensities generate an asymmetric field profile in the nano-rod array inducing an off-axis beam deflection.
The bolometric focal plane array of the Polarbear CMB experiment  [PDF]
K. Arnold,P. A. R. Ade,A. E. Anthony,D. Barron,D. Boettger,J. Borrill,S. Chapman,Y. Chinone,M. A. Dobbs,J. Errard,G. Fabbian,D. Flanigan,G. Fuller,A. Ghribi,W. Grainger,N. Halverson,M. Hasegawa,K. Hattori,M. Hazumi,W. L. Holzapfel,J. Howard,P. Hyland,A. Jaffe,B. Keating,Z. Kermish,T. Kisner,M. Le Jeune,A. T. Lee,E. Linder,M. Lungu,F. Matsuda,T. Matsumura,N. J. Miller,X. Meng,H. Morii,S. Moyerman,M. J. Myers,H. Nishino,H. Paar,E. Quealy,C. Reichardt,P. L. Richards,C. Ross,A. Shimizu,C. Shimmin,M. Shimon,M. Sholl,P. Siritanasak,H. Spieler,N. Stebor,B. Steinbach,R. Stompor,A. Suzuki,T. Tomaru,C. Tucker,O. Zahn
Physics , 2012, DOI: 10.1117/12.927057
Abstract: The Polarbear Cosmic Microwave Background (CMB) polarization experiment is currently observing from the Atacama Desert in Northern Chile. It will characterize the expected B-mode polarization due to gravitational lensing of the CMB, and search for the possible B-mode signature of inflationary gravitational waves. Its 250 mK focal plane detector array consists of 1,274 polarization-sensitive antenna-coupled bolometers, each with an associated lithographed band-defining filter. Each detector's planar antenna structure is coupled to the telescope's optical system through a contacting dielectric lenslet, an architecture unique in current CMB experiments. We present the initial characterization of this focal plane.
Millimeter-wave vector modulator and its application in active phased array antenna

HAN Ke-Wu,YANG Ming-Hui,SUN Yun,LI Ling-Yun,HOU Yang,SUN Xiao-Wei,

红外与毫米波学报 , 2011,
Abstract: Vector modulator can be employed in active phased array antenna(APAA)as a replacement of conventional digital phase shifter and attenuator for its capability of simultaneously realizing millimeter-wave direct carrier modulation on phase and amplitude.A millimeter wave vector modulator was realized with advanced GaAs pHEMT process, and onchip measurement has shown that -12~-40 dB amplitude modulation and 360? phase modulation was achieved. A Ka band 1?8 array experimental APAA composed of vector modulators was designed and proved to steer the beam scanning effectively. It was demonstrated that APAA based on vector modulation technique is feasible.
Generalized refraction using lenslet arrays  [PDF]
Alasdair C. Hamilton,Johannes Courtial
Physics , 2009, DOI: 10.1088/1464-4258/11/6/065502
Abstract: We have recently started to investigate 2D arrays of confocal lens pairs. Miniaturization of the lens pairs can make the array behave ray-optically like a homogeneous medium. Here we generalize the geometry of the lens pairs. These generalisations include a sideways shift of the lens centres and a change in the orientation of both lenses in each pair. We investigate the basic ray optics of the resulting arrays, and illustrate these with movies rendered using ray-tracing software. We suggest that confocal lenslet arrays could be used to realize ray-optically some recent metamaterials concepts such as the coordinate-transform design paradigm.
Apertif - the focal-plane array system for the WSRT  [PDF]
Tom Oosterloo,Marc Verheijen,Wim van Cappellen,Laurens Bakker,George Heald,Marianna Ivashina
Physics , 2009,
Abstract: We describe a focal plane array (FPA) system, called Apertif, that is being developed for the Westerbork Synthesis Radio Telescope (WSRT). The aim of Apertif is to increase the instantaneous field of view of the WSRT by a factor of 37 and its observing bandwidth to 300 MHz with high spectral resolution. This system will turn the WSRT into an effective survey telescope with scientific applications such as deep imaging surveys of the northern sky of HI and OH emission, of the polarised continuum and efficient searches for pulsars and transients. Such surveys will detect the HI in more than 100,000 galaxies out to z = 0.4, will allow to determine the detailed structure of the magnetic field of the Galaxy, and will discover more than 1,000 pulsars. We present experimental results obtained with a prototype FPA installed in one of the WSRT dishes. These results demonstrate that FPAs do have the performance that is required to make all these surveys possible.
Infrared Image Restoration Algorithm Based on Substrate-free Focal Plane Array

WU Jian-xiong,CHENG Teng,ZHANG Qing-chuan,GAO Jie,CHEN Da-peng,

实验力学 , 2012,
Abstract: It is different from traditional substrate with focal plane array that thermal sensitive element of substrate-free focal plane array can absorb infrared radiation. The absorbed infrared radiation is conducted to adjacent cells in the form of a point spread function. Although this thermal characteristic can improve infrared detection performance greatly and can make the infrared target much more prominent against the background, but at the same time the thermal characteristic is able to reduce the infrared target detail distinguishing ability and result in image blurring. In this regard, through analyzing the thermal diffusion additive effect on infrared imaging quality, and using digital image processing method, a targeted image restoration algorithm is proposed in this paper to solve above problem. Both simulative and experimental results show that the image restoration algorithm can effectively enhance the detail contours of infrared image then highly improve image quality.
Standard and non-standard metarefraction with confocal lenslet arrays  [PDF]
Johannes Courtial
Physics , 2009, DOI: 10.1016/j.optcom.2009.03.046
Abstract: A recent paper demonstrated that two lenslet arrays with focal lengths f_1 and f_2, separated by f_1 + f_2, change the direction of transmitted light rays approximately like the interface between isotropic media with refractive indices n_1 and n_2, where n_1 / n_2 = - f_1 / f_2 [J. Courtial, New J. Phys. 10, 083033 (2008)]. This is true if light passes through corresponding lenslets, that is lenslets that share an optical axis. Light can also pass through different combinations of non-corresponding lenslets. Such light can be either absorbed or allowed to form "ghost images"; either way, it leads to a limitation of the field of view of confocal lenslet arrays. This paper describes, qualitatively and quantitatively, a number of such field-of-view limitations.
Quantifying metarefraction with confocal lenslet arrays  [PDF]
Tautvydas Maceina,Gediminas Juzeliunas,Johannes Courtial
Physics , 2011, DOI: 10.1016/j.optcom.2011.06.058
Abstract: METATOYs can change the direction of light in ways that appear to, but do not actually, contravene the laws of wave optics. This direction change applies only to part of the transmitted light beam; the remainder gets re-directed differently. For a specific example, namely confocal pairs of rectangular lenslet arrays with no dead area between lenslets, we calculate here the fractions of power of a uniform-intensity light beam incident from a specific (but arbitrary) direction that get re-directed in different ways, and we derive an equation describing this redirection. This will facilitate assessment of the suitability of METATOYs for applications such as solar concentration. Finally, we discuss similarities between the multiple refraction of light at the lenslet arrays and multiple refraction and reflection of cold atoms at a barrier in the presence of the light fields.
Law of refraction for generalised confocal lenslet arrays  [PDF]
Stephen Oxburgh,Chris D. White,Georgios Antoniou,Johannes Courtial
Physics , 2013, DOI: 10.1016/j.optcom.2013.10.017
Abstract: We derive the law of generalised refraction for generalised confocal lenslet arrays, which are arrays of misaligned telescopes. We have implemented this law of refraction in TIM, a custom open-source ray tracer.
Thermal and mechanical characterizations of asubstrate-free focal plane array

Cheng Teng,Zhang Qing-Chuan,Chen Da-Peng,Shi Hai-Tao,Gao Jie,Qian Jian,Wu Xiao-Ping,

中国物理 B , 2010,
Abstract: We propose a substrate-free focal plane array (FPA) in this paper. The solid substrate is completely removed, and the microcantilevers extend from a supporting frame. Using finite element analysis, the thermal and mechanical characterizations of the substrate-free FPA are presented. Because of the large decrease in thermal conductance, the supporting frame is temperature dependent, which brings out a unique feature: the lower the thermal conductance of the supporting frame is, the higher the energy conversion efficiency in the substrate-free FPA will be. The results from the finite element analyses are consistent with our measurements: two types of substrate-free FPAs with pixel sizes of 200$\times $200 and 60$\times $60~$\mu $m$^{2}$ are implemented in the proposed infrared detector. The noise equivalent temperature difference ({NETD}) values are experimentally measured to be 520 and 300~mK respectively. Further refinements are considered in various aspects, and the substrate-free FPA with a pixel size of 30$\times $30~$\mu $m$^{2}$ has a potential of achieving an {NETD} value of 10~mK.
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