Wide-field Fizeau imaging telescope: experimental results

A nine-aperture, wide-field Fizeau imaging telescope has been built at the Lockheed-Martin Advanced Technology Center. The telescope consists of nine, 125 mm diameter collector telescopes coherently phased and combined to form a diffraction-limited image with a resolution that is consistent with the 610 mm diameter of the telescope. The phased field of view of the array is 1 murad. The measured rms wavefront error is 0.08 waves rms at 635 nm. The telescope is actively controlled to correct for tilt and phasing errors. The control sensing technique is the method known as phase diversity, which extracts wavefront information from a pair of focused and defocused images. The optical design of the telescope and typical performance results are described.     

Toward perfect antireflection coatings. 3. Experimental results obtained with the use of Reststrahlen materials

The equipment and methods used to produce wide-angle antireflection coatings based on Reststrahlen materials are described. The optical constants of the coating materials used in the construction of the multilayers were determined by spectrophotometric ellipsometry and are compared with the literature values. The measured performance of an experimentally produced antireflection coating is compared with the expected calculated performance. The reflectance is low over a wide range of angles, but only in the narrow-wavelength region at which the refractive index of the Reststrahlen material is close to unity.     

Study of colloidal quantum-dot surfaces using an innovative thin-film positron 2D-ACAR method

Nanosized inorganic particles are of great interest because their electronic properties can be easily tailored, providing a tremendous potential for applications in optoelectronic devices, light-emitting diodes, solar cells and hydrogen storage. Confinement of electrons and holes to dimensions comparable to their wavelength leads to quantum-well states with modified wavefunctions and density of states. Surface phenomena are crucial in determining nanoparticle properties in view of their large surface-to-volume ratio. Despite a wealth of information, many fundamental questions about the nature of the surface and its relationship with the electronic structure remain unsolved. Ab initio calculations on CdSe nanocrystals suggest that passivating the ligands does not produce the ideal wurtzite structure and that Se atoms relax outwards irrespective of passivation. Here we show that implanted positrons are trapped at the surface of CdSe nanocrystals. They annihilate mostly with the Se electrons, monitor changes in composition and structure of the surface while hardly sensing the ligand molecules, and we thus unambiguously confirm the predicted strong surface relaxation.     

Zu Verformungsverhalten und Rissgefährdung einer mineralischen Abdichtung im Deponiebau – infolge gekoppelter zyklischer hydraulischer und mechanischer Beanspruchung

Deformation behaviour and crack initalisation of clay liner related to landfills – due to cyclic hydraulic and mechanic actions. Settlement and swell/shrink behaviour of clay liner under influence of environment are major topics of many research studies focussing expansive soil behaviour related to landfill applications. Depending on magnitude of surcharge pressure acting on the liner and wetting‐drying behaviour of the soil, settlement, together with swelling and shrinkage, may result in cracks or contrastly may close initial cracks induced by mechanical compaction in the field. In this paper, an analysis of the effects of field swelling and shrinkage of a compacted polymer‐enhanced bentonite‐sand mixture is presented. The analysis performed was based on field suction measurement data. Two different approaches; namely, single‐valued effective stress concept and two‐independent stress state variable approach for unsaturated soils were adopted in the analysis and comparison is presented in this paper.     

22-nm Half-pitch extreme ultraviolet node development at the SEMATECH Berkeley microfield exposure tool

Microfield exposure tools continue to play a dominant role in the development of extreme ultraviolet (EUV) resists. Here we present an update on the SEMATECH Berkeley 0.3-NA microfield exposure tool and summarize the latest test results from high-resolution line-space printing. Printing down to 20-nm is presented with large process latitude at 22-nm half-pitch lines. Also presented are line-edge roughness results along with a discussion of the importance of mask contributors to line-edge roughness measured in resist. Finally we briefly describe an upgrade to the tool that will enable EUV resist development at the 16-nm half-pitch node and beyond. (This paper was presented in MNE 2008 conference, <http://www.mne08.org>, <http://www.mne-conf.org>).     

现代化数字有线电视系统的紧急报警系统

借着有线电视数字化及通过地区和全国高速数据传送网络实现的有线电视系统网络互连,中国实施地区和全国紧急报警系统（EAS）成为可能。紧急报警系统使政府能够在电视上发布重要的公共安全信息和警告。这些警告信息可用三种方式呈现给电视观众：覆盖音频、调到有紧急信息的电视频道及显示文字或图像信息。其中一种或多种选择可用于传达紧急信息,文字和图形叠加功能对EAS系统很重要。对于有效的EAS系统来说,重要的是,不管电视或机顶盒是什么款式、型号、软件、固件或硬件版本、家庭使用什么终端来接收电视信号,紧急报警信息都能在所有电视上被看到和听到。EAS系统还可用于传送政府发布的重要公共非紧急信息。     

Dosimetric calculations for uranium miners for epidemiological studies

Epidemiological studies on uranium miners are being carried out to quantify the risk of cancer based on organ dose calculations. Mathematical models have been applied to calculate the annual absorbed doses to regions of the lung, red bone marrow, liver, kidney and stomach for each individual miner arising from exposure to radon gas, radon progeny and long-lived radionuclides (LLR) present in the uranium ore dust and to external gamma radiation. The methodology and dosimetric models used to calculate these organ doses are described and the resulting doses for unit exposure to each source (radon gas, radon progeny and LLR) are presented. The results of dosimetric calculations for a typical German miner are also given. For this miner, the absorbed dose to the central regions of the lung is dominated by the dose arising from exposure to radon progeny, whereas the absorbed dose to the red bone marrow is dominated by the external gamma dose. The uncertainties in the absorbed dose to regions of the lung arising from unit exposure to radon progeny are also discussed. These dose estimates are being used in epidemiological studies of cancer in uranium miners.     

Generalized laws of refraction that can lead to wave-optically forbidden light-ray fields

The recent demonstration of a metamaterial phase hologram so thin that it can be classified as an interface in the effective-medium approximation [Science 334, 333 (2011)] has dramatically increased interest in generalized laws of refraction. Based on the fact that scalar wave optics allows only certain light-ray fields, we divide generalized laws of refraction into two categories. When applied to a planar cross section through any allowed light-ray field, the laws in the first category always result in a cross section through an allowed light-ray field again, whereas the laws in the second category can result in a cross section through a forbidden light-ray field.     

Airborne and satellite remote sensing of the mid-infrared water vapour continuum

Remote sensing of the atmosphere from space plays an increasingly important role in weather forecasting. Exploiting observations from the latest generation of weather satellites relies on an accurate knowledge of fundamental spectroscopy, including the water vapour continuum absorption. Field campaigns involving the Facility for Airborne Atmospheric Measurements research aircraft have collected a comprehensive dataset, comprising remotely sensed infrared radiance observations collocated with accurate measurements of the temperature and humidity structure of the atmosphere. These field measurements have been used to validate the strength of the infrared water vapour continuum in comparison with the latest laboratory measurements. The recent substantial changes to self-continuum coefficients in the widely used MT_CKD (Mlawer-Tobin-Clough-Kneizys-Davies) model between 2400 and 3200?cm(-1) are shown to be appropriate and in agreement with field measurements. Results for the foreign continuum in the 1300-2000?cm(-1) band suggest a weak temperature dependence that is not currently included in atmospheric models. A one-dimensional variational retrieval experiment is performed that shows a small positive benefit from using new laboratory-derived continuum coefficients for humidity retrievals.     

Phase selection enabled formation of abrupt axial heterojunctions in branched oxide nanowires

Rational synthesis of nanowires via the vapor-liquid-solid (VLS) mechanism with compositional and structural controls is vitally important for fabricating functional nanodevices from bottom up. Here, we show that branched indium tin oxide nanowires can be in situ seeded in vapor transport growth using tailored Au-Cu alloys as catalyst. Furthermore, we demonstrate that VLS synthesis gives unprecedented freedom to navigate the ternary In-Sn-O phase diagram, and a rare and bulk-unstable cubic phase can be selectively stabilized in nanowires. The stabilized cubic fluorite phase possesses an unusual almost equimolar concentration of In and Sn, forming a defect-free epitaxial interface with the conventional bixbyite phase of tin-doped indium oxide that is the most employed transparent conducting oxide. This rational methodology of selecting phases and making abrupt axial heterojunctions in nanowires presents advantages over the conventional synthesis routes, promising novel composition-modulated nanomaterials.