1,885 research outputs found
A versatile high resolution objective for imaging quantum gases
We present a high resolution objective lens made entirely from catalog
singlets that has a numerical aperture of 0.36. It corrects for aberrations
introduced by a glass window and has a long working distance of 35mm, making it
suitable for imaging objects within a vacuum system. This offers simple high
resolution imaging for many in the quantum gas community. The objective
achieves a resolution of 1.3{\mu}m at the design wavelength of 780nm, and a
diffraction-limited field of view of 360{\mu}m when imaging through a 5mm
window. Images of a resolution target and a pinhole show quantitative agreement
with the simulated lens performance. The objective is suitable for
diffraction-limited imaging on the D2 line of all the alkalis by changing only
the aperture diameter, retaining numerical apertures above 0.32. The design
corrects for window thicknesses of up to 15mm if the singlet spacings are
modified
Experiences in the Integration of Design Across the Mechanical Engineering Curriculum
The Faculty of the School of Mechanical Engineering at Purdue University have effected a major change in the Purdue Mechanical Engineering program by integrating design throughout the curriculum. In doing so, a significant level of faculty interaction has been achieved as well. The goals of the curriculum revision are: (1) to improve student skills in how to solve open-ended design problems, (2) to reduce the core of the curriculum to allow flexibility in course selection, and allow time for solving design problems, (3) to improve student skills in team work and communications, and (4) to improve student skills in using computers as tools for solving engineering problems. Reduction of the core allowed the addition of a sophomore cornerstone design course. This cornerstone course teaches students how to solve open-ended problems, bridging the gap between solution strategies that are effective for the science and mathematics courses, and those needed to solve open-ended engineering problems. The design fundamentals taught in the cornerstone course are applied in the core courses, such as heat transfer, thermodynamics, instrumentation, and machine design. The senior design experience comes primarily from a design elective and the capstone design course. This paper presents an overview of the curriculum revision process, and the changes which resulted from it. It also discusses the issues associated with infusing design projects into core courses which have traditionally focused on teaching engineering science fundamentals. Plans for the future evolution of the curriculum are also discussed
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Distinctive impact craters are formed by organic rich cometary dust grains
Introduction: Preliminary Examination (PE) of the Stardust cometary collector revealed many tracks in the silica aerogel and impact craters on aluminium (Al) foil, from which Wild 2 dust particle fluence and size distribution were determined. Laboratory light gas gun (LGG) shots provided impactor size calibrations. Analogue impacts of diverse mineral compositions and aggregate particles aided
interpretation of dust composition and structure. We now describe our recent impact experiments on foil by organic materials, which reveal distinctive crater surface textures, and even preserved residue
Precise wavefunction engineering with magnetic resonance
Controlling quantum fluids at their fundamental length scale will yield
superlative quantum simulators, precision sensors, and spintronic devices. This
scale is typically below the optical diffraction limit, precluding precise
wavefunction engineering using optical potentials alone. We present a protocol
to rapidly control the phase and density of a quantum fluid down to the healing
length scale using strong time-dependent coupling between internal states of
the fluid in a magnetic field gradient. We demonstrate this protocol by
simulating the creation of a single stationary soliton and double soliton
states in a Bose-Einstein condensate with control over the individual soliton
positions and trajectories, using experimentally feasible parameters. Such
states are yet to be realized experimentally, and are a path towards
engineering soliton gases and exotic topological excitations.Comment: 8+ pages, 3 figures; revised parameters and added section about
optimisation of adiabatic, finite-duration pulses and analytic resolution
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