60,715 research outputs found
Video-rate computational super-resolution and integral imaging at longwave-infrared wavelengths
We report the first computational super-resolved, multi-camera integral
imaging at long-wave infrared (LWIR) wavelengths. A synchronized array of FLIR
Lepton cameras was assembled, and computational super-resolution and
integral-imaging reconstruction employed to generate video with light-field
imaging capabilities, such as 3D imaging and recognition of partially obscured
objects, while also providing a four-fold increase in effective pixel count.
This approach to high-resolution imaging enables a fundamental reduction in the
track length and volume of an imaging system, while also enabling use of
low-cost lens materials.Comment: Supplementary multimedia material in
http://dx.doi.org/10.6084/m9.figshare.530302
De-biasing interferometric visibilities in VLTI-AMBER data of low SNR observations
AIMS: We have found that the interferometric visibilities of VLTI-AMBER
observations, extracted via the standard reduction package, are significantly
biased when faint targets are concerned. The visibility biases derive from a
time variable fringing effect (correlated noise) appearing on the detector.
METHODS: We have developed a method to correct this bias that consists in a
subtraction of the extra power due to such correlated noise, so that the real
power spectrum at the spatial frequencies of the fringing artifact can be
restored. RESULTS: This pre-processing procedure is implemented in a software,
called AMDC and available to the community, to be run before the standard
reduction package. Results obtained on simulated and real observations are
presented and discussed.Comment: 7 pages, 9 figure
Simultaneous real-time visible and infrared video with single-pixel detectors
Conventional cameras rely upon a pixelated sensor to provide spatial resolution. An alternative approach replaces the sensor with a pixelated transmission mask encoded with a series of binary patterns. Combining knowledge of the series of patterns and the associated filtered intensities, measured by single-pixel detectors, allows an image to be deduced through data inversion. In this work we extend the concept of a ‘single-pixel camera’ to provide continuous real-time video at 10 Hz , simultaneously in the visible and short-wave infrared, using an efficient computer algorithm. We demonstrate our camera for imaging through smoke, through a tinted screen, whilst performing compressive sampling and recovering high-resolution detail by arbitrarily controlling the pixel-binning of the masks. We anticipate real-time single-pixel video cameras to have considerable importance where pixelated sensors are limited, allowing for low-cost, non-visible imaging systems in applications such as night-vision, gas sensing and medical diagnostics
The Brazilian Tunable Filter Imager for the SOAR telescope
This paper presents a new Tunable Filter Instrument for the SOAR telescope.
The Brazilian Tunable Filter Imager (BTFI) is a versatile, new technology,
tunable optical imager to be used in seeing-limited mode and at higher spatial
fidelity using the SAM Ground-Layer Adaptive Optics facility at the SOAR
telescope. The instrument opens important new science capabilities for the SOAR
community, from studies of the centers of nearby galaxies and the insterstellar
medium to statistical cosmological investigations. The BTFI takes advantage of
three new technologies. The imaging Bragg Tunable Filter concept utilizes
Volume Phase Holographic Gratings in a double-pass configuration, as a tunable
filter, while a new Fabry-Perot (FP) concept involves technologies which allow
a single FP etalon to act over a large range of interference orders and
spectral resolutions. Both technologies will be in the same instrument.
Spectral resolutions spanning the range between 25 and 30,000 can be achieved
through the use of iBTF at low resolution and scanning FPs beyond R ~2,000. The
third new technologies in BTFI is the use of EMCCDs for rapid and cyclically
wavelength scanning thus mitigating the damaging effect of atmospheric
variability through data acquisition. An additional important feature of the
instrument is that it has two optical channels which allow for the simultaneous
recording of the narrow-band, filtered image with the remaining (complementary)
broad-band light. This avoids the uncertainties inherent in tunable filter
imaging using a single detector. The system was designed to supply tunable
filter imaging with a field-of-view of 3 arcmin on a side, sampled at 0.12" for
direct Nasmyth seeing-limited area spectroscopy and for SAM's visitor
instrument port for GLAO-fed area spectroscopy. The instrument has seen first
light, as a SOAR visitor instrument. It is now in comissioning phase.Comment: accepted in PAS
Nano-displacement measurements using spatially multimode squeezed light
We demonstrate the possibility of surpassing the quantum noise limit for
simultaneous multi-axis spatial displacement measurements that have zero mean
values. The requisite resources for these measurements are squeezed light beams
with exotic transverse mode profiles. We show that, in principle, lossless
combination of these modes can be achieved using the non-degenerate Gouy phase
shift of optical resonators. When the combined squeezed beams are measured with
quadrant detectors, we experimentally demonstrate a simultaneous reduction in
the transverse x- and y- displacement fluctuations of 2.2 dB and 3.1 dB below
the quantum noise limit.Comment: 21 pages, 9 figures, submitted to "Special Issue on Fluctuations &
Noise in Photonics & Quantum Optics" of J. Opt.
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