22,914 research outputs found
All-Sky Near Infrared Space Astrometry
Gaia is currently revolutionizing modern astronomy. However, much of the
Galactic plane, center and the spiral arm regions are obscured by interstellar
extinction, rendering them inaccessible because Gaia is an optical instrument.
An all-sky near infrared (NIR) space observatory operating in the optical NIR,
separated in time from the original Gaia would provide microarcsecond NIR
astrometry and millimag photometry to penetrate obscured regions unraveling the
internal dynamics of the Galaxy.Comment: 7 page
Holographic and ultrasonic detection of bond flaws in aluminum panels reinforced with boron-epoxy
An experimental investigation was made of the application of holographic interferometry to the nondestructive detection of unbonded areas (flaws) in bonded panels. Flaw detection results were compared with results obtained with an ultrasonic flaw detector. Holography, with panel deformation accomplished by a reduction in ambient pressure, is less sensitive for flaws beneath 5 and 10 plies of boron-epoxy than the ultrasonic method, though it does have its operational advantages. A process for the manufacture of bonded panels which incorporate known unbonded areas was also developed. The unbonded areas were formed without the use of foreign materials, which makes the method suitable for the construction of reference standards for bonded panels whenever needed for the proper setup of ultrasonic flaw-detection instruments
Development of large radii half-wave plates for CMB satellite missions
The successful European Space Agency (ESA) Planck mission has mapped the
Cosmic Microwave Background (CMB) temperature anisotropy with unprecedented
accuracy. However, Planck was not designed to detect the polarised components
of the CMB with comparable precision. The BICEP2 collaboration has recently
reported the first detection of the B-mode polarisation. ESA is funding the
development of critical enabling technologies associated with B-mode
polarisation detection, one of these being large diameter half-wave plates. We
compare different polarisation modulators and discuss their respective
trade-offs in terms of manufacturing, RF performance and thermo-mechanical
properties. We then select the most appropriate solution for future satellite
missions, optimized for the detection of B-modes.Comment: 16 page
Manufacture of astroloy turbine disk shapes by hot isostatic pressing, volume 1
The Materials in Advanced Turbine Engines project was conducted to demonstrate container technology and establish manufacturing procedures for fabricating direct Hot Isostatic Pressing (HIP) of low carbon Astroloy to ultrasonic disk shapes. The HIP processing procedures including powder manufacture and handling, container design and fabrication, and HIP consolidation techniques were established by manufacturing five HIP disks. Based upon dimensional analysis of the first three disks, container technology was refined by modifying container tooling which resulted in closer conformity of the HIP surfaces to the sonic shape. The microstructure, chemistry and mechanical properties of two HIP low carbon Astroloy disks were characterized. One disk was subjected to a ground base experimental engine test, and the results of HIP low carbon Astroloy were analyzed and compared to conventionally forged Waspaloy. The mechanical properties of direct HIP low carbon Astroloy exceeded all property goals and the objectives of reduction in material input weight and reduction in cost were achieved
ICI optical data storage tape
Optical data storage tape is now a commercial reality. The world's first successful development of a digital optical tape system is complete. This is based on the Creo 1003 optical tape recorder with ICI 1012 write-once optical tape media. Several other optical tape drive development programs are underway, including one using the IBM 3480 style cartridge at LaserTape Systems. In order to understand the significance and potential of this step change in recording technology, it is useful to review the historical progress of optical storage. This has been slow to encroach on magnetic storage, and has not made any serious dent on the world's mountains of paper and microfilm. Some of the reasons for this are the long time needed for applications developers, systems integrators, and end users to take advantage of the potential storage capacity; access time and data transfer rate have traditionally been too slow for high-performance applications; and optical disk media has been expensive compared with magnetic tape. ICI's strategy in response to these concerns was to concentrate its efforts on flexible optical media; in particular optical tape. The manufacturing achievements, media characteristics, and media lifetime of optical media are discussed
Molybdenum sputtering film characterization for high gradient accelerating structures
Technological advancements are strongly required to fulfill the demands of
new accelerator devices with the highest accelerating gradients and operation
reliability for the future colliders. To this purpose an extensive R&D
regarding molybdenum coatings on copper is in progress. In this contribution we
describe chemical composition, deposition quality and resistivity properties of
different molybdenum coatings obtained via sputtering. The deposited films are
thick metallic disorder layers with different resistivity values above and
below the molibdenum dioxide reference value. Chemical and electrical
properties of these sputtered coatings have been characterized by Rutherford
backscattering, XANES and photoemission spectroscopy. We will also present a
three cells standing wave section coated by a molybdenum layer 500 nm
thick designed to improve the performance of X-Band accelerating systems.Comment: manuscript has been submitted and accepted by Chinese Physics C
(2012
Ultrafast optical ranging using microresonator soliton frequency combs
Light detection and ranging (LIDAR) is critical to many fields in science and
industry. Over the last decade, optical frequency combs were shown to offer
unique advantages in optical ranging, in particular when it comes to fast
distance acquisition with high accuracy. However, current comb-based concepts
are not suited for emerging high-volume applications such as drone navigation
or autonomous driving. These applications critically rely on LIDAR systems that
are not only accurate and fast, but also compact, robust, and amenable to
cost-efficient mass-production. Here we show that integrated dissipative
Kerr-soliton (DKS) comb sources provide a route to chip-scale LIDAR systems
that combine sub-wavelength accuracy and unprecedented acquisition speed with
the opportunity to exploit advanced photonic integration concepts for
wafer-scale mass production. In our experiments, we use a pair of free-running
DKS combs, each providing more than 100 carriers for massively parallel
synthetic-wavelength interferometry. We demonstrate dual-comb distance
measurements with record-low Allan deviations down to 12 nm at averaging times
of 14 s as well as ultrafast ranging at unprecedented measurement rates of
up to 100 MHz. We prove the viability of our technique by sampling the
naturally scattering surface of air-gun projectiles flying at 150 m/s (Mach
0.47). Combining integrated dual-comb LIDAR engines with chip-scale
nanophotonic phased arrays, the approach could allow widespread use of compact
ultrafast ranging systems in emerging mass applications.Comment: 9 pages, 3 figures, Supplementary information is attached in
'Ancillary files
- …