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This PDF file contains the front matter associated with SPIE Proceedings Volume 8178, including the Title Page, Copyright information, Table of Contents, Introduction, and the Conference Committee listing.
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It is well known that luminance from photo-chemical reactions of hydroxyl ions in the upper atmosphere (~85 km
altitude) produces a significant amount of night time radiation in the short wave infra-red (SWIR) band with
wavelength between 0.9 and 1.7 μm. This air glow has been proposed as an illumination source for obtaining
imagery in the dark of night. By examining short term nightly fluctuations and long term seasonal trends in the
ground level irradiance we hope to determine the source reliability for night time low light surveillance and imaging.
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It is well known that luminance from photo-chemical reactions of hydroxyl ions in the upper atmosphere (~85 km
altitude) produces a significant amount of night time radiation in the short wave infra-red (SWIR) band between
0.9 and 1.7 μm wave length. This phenomenon, often referred to as airglow, has been demonstrated as an effective
illumination source for passive low light level night time imaging applications. It addition it has been shown that
observation of the spatial and temporal variations of the illumination can be used to characterize atmospheric tidal
wave actions in the airglow region. These spatio-temporal variations manifest themselves as traveling wave
patterns whose period and velocity are related to the wind velocity at 85 km as well as the turbulence induced by
atmospheric vertical instabilities. In this paper we present nearly a year of airglow observations over the whole
sky, showing long term and short term fluctuations to characterize SWIR night time image system performance.
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Intensity interferometery holds tremendous potential for remote sensing of space objects. Whereas spatial
resolution of imagery obtained from earth-based observatories is typically limited by both the size of the
primary mirror and atmospheric effects, intensity interferometers (IIs) are relatively unaffected by
atmospheric distortions and their effective apertures can be substantially larger than is practical for
traditional observatories. Most intensity interferometer measurements have been performed in the visible
region due to well-known issues of poor signal to noise ratios and the performance of detectors in the
visible spectral bands. In fact the short-wave infrared (SWIR) spectral band is relatively unexplored for II
applications. In this paper we investigate the measurement signal to noise terms for a notional SWIR
intensity interferometer. Our study goes beyond the most basic SNR equations of II, and analyzes
atmospheric effects, sky backgrounds, and detector characteristics, considering the current state-of-the-art
for experiments in the short-wave infrared spectral region.
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Generally available satellite images, e. g. from the MODIS sensor, provide data in spectral bands, which are suitable for
remote sensing applications and earth surface observations. However, for some applications different bands as well as
specific cloud formations for a certain region may be of interest, thus making the simulation of background data
essential. Therefore, the software MATISSE ("Advanced Modeling of the Earth for Environment and Scenes
Simulation") proved to be the appropriate tool. MATISSE is an infrared background scene generator developed by
ONERA for computing natural background spectral radiance images including atmosphere, sea, land and high and low
altitude clouds. In order to validate the model, comparisons with MODIS satellite data have been carried out using
images in available spectral bands. The investigations comprised selected surface structures like sea, desert, lowland
(dry) and highlands (humid). In general, the results on radiance images show a good correlation between MODIS image
and the MATISSE-simulation.
This paper focuses on comparing results between simulated MATISSE radiance images and the MODIS observations.
Based on this, possible sources of error and the limits of the model are discussed.
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The validation of the sea surface infrared optical properties multiresolution model developed at ONERA is investigated
by comparison with measurements. The images were obtained during the MIRAMER campaign that took place in May
2008 in the Mediterranean Sea. The sea radiance model and optical properties are expressed and the experimental setup
of the campaign is briefly presented. We focus on solar glint measurements collected the 22 th of May at 5 h 59mn 50s
in the MWIR bandwidth on-board the R/V ATALANTE at grazing observational angle. A sensitivity analysis of glitter
radiance on atmospheric and aerosol profiles in the vicinity of the measured contextual parameters is presented. Modelled
and measured images are compared and results are delved further by comparisons of histograms, averaged vertical and
horizontal profiles. Errors are under those potentially due to calibration. Finally, a sensitivity analysis upon uncertainties
on contextual parameters involved in sea radiance computation is made.
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Knowledge on the marine boundary layer is of importance for the prediction of the optical image quality obtained from
long range targets. One property of the boundary layer, that can be studied rather easily by means of optical refraction
measurements, is the vertical temperature profile. This profile can be compared with the profile, as predicted by the
generally accepted Monin-Obukhov (M-O) similarity theory, such as applied in the EOSTAR model, developed at TNO.
This model also predicts the atmospheric turbulence profile, for which a validation can be done by means of scintillation
measurements. Along these lines we explored the data from the year-round FATMOSE experiment, arranged over the
False Bay (South-Africa). Because of the large amount of refraction and scintillation data, supported by extensive data
from various local weather stations, we could select the conditions for which the M-O theory is valid and determine the
particular conditions where this theory is failing. In the paper model predictions (including Angle of Arrival calculations
in non-homogeneous conditions along the 15.7 km path) and associated refraction and scintillation measurements are
shown for a representative variety of conditions.
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Operation and design of electro-optical systems are affected by atmospheric optical turbulence quantified by the
refractive index parameter Cn2. Regarding wave propagation in the visible and infrared (IR), Cn2 is a function of height,
dependant on temperature, pressure, and the structure temperature function parameter Cn2. The long-term experiment
VerTurM (vertical turbulence measurements) was designed to characterize the vertical variations of optical turbulence up
to 250 m in the lower atmospheric boundary layer for a moderate typical central European climate. Since May 2009 three
independent measurement systems have been operated in a flat pasture site in north-western Germany. In the atmospheric
surface layer at a tall tower sonic anemometer measurements are performed on four discrete heights between 4 and 64 m
providing information about atmospheric stability and turbulence. Cn2 is derived. From 30 to 250 m a SODAR-RASS
system (Sound Detection and Ranging - Radio acoustic sounding system) yields every half an hour profiles of Cn2. Additional direct measurements of Cn2 have been performed near the ground using a scintillometer. First results of the
three measurement systems are presented. Vertical profiles and stability dependence are analysed in respect of Monin-
Obukhov-similarity theory (MOST). Differences in the measurement systems and the expected height variations are
discussed.
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PICARD is a space mission developed mainly to study the geometry of the Sun. The satellite was launched in
June 2010. The PICARD mission has a ground program which is based at the Calern Observatory (Observatoire
de la C^ote d'Azur). It will allow recording simultaneous solar images from ground. Astrometric observations
of the Sun using ground-based telescopes need however an accurate modelling of optical e®ects induced by
atmospheric turbulence. Previous works have revealed a dependence of the Sun radius measurements with the
observation conditions (Fried's parameter, atmospheric correlation time(s) ...). The ground instruments consist
mainly in SODISM II, replica of the PICARD space instrument and MISOLFA, a generalized daytime seeing
monitor. They are complemented by standard sun-photometers and a pyranometer for estimating a global sky
quality index. MISOLFA is founded on the observation of Angle-of-Arrival (AA) °uctuations and allows us to
analyze atmospheric turbulence optical e®ects on measurements performed by SODISM II. It gives estimations of
the coherence parameters characterizing wave-fronts degraded by the atmospheric turbulence (Fried's parameter,
size of the isoplanatic patch, the spatial coherence outer scale and atmospheric correlation times). This paper
presents an overview of the ground based instruments of PICARD and some results obtained from observations
performed at Calern observatory in 2011.
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In this article, the characteristic features of formation of the Bessel optical beam in a turbulent atmosphere are analyzed.
The problem analysis is based on the solution of the equation for the mutual coherence function (the second-order field
moment) of a Bessel beam of optical radiation. The behavior of the spatial coherence radius of a Bessel optical beam
depending on parameters of a beam and characteristics of the turbulent atmosphere is examined. It has appeared, that at
low levels of fluctuations in a turbulent atmosphere the spatial coherence radius of a Bessel optical beam is larger than
the spatial coherence radius of a plane optical wave, but it is smaller than the spatial coherence radius of a spherical
wave. At high levels of fluctuations in a turbulent atmosphere, the spatial coherence radius of a Bessel beam becomes
closer to the similar characteristic of a spherical wave.
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The improvement of the parametrix method for solving the full system of the Navier-Stokes is presented. As known the
fundamental solution equation is an oscillatory one. These oscillations are observed while analyzing the density
evolution. Their frequency diminishes as the time grows. The approximate expression is presented for density in the
neighborhood of a vortical structure. The laser beam propagation has been analyzed. The method will enable to find time
average quantities.
We considered the mathematical theory of the laser-schlieren technique. Experimental data on grid-generated turbulence
are presented.
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At propagation of a light field through atmosphere it is exposed to turbulent distortions. For reduction of their
influence adaptive optical systems (AOS) are used. One of the important problems in work AOS is its speed
limited to action of the correcting mirror. Here proposed the methods to reduce the influence of delay system
on the accuracy of its work. Carried out the comparative analysis of accuracy of definition of centroids
coordinates for the cameras, built on the basis of CCD and CMOS technologies. Considered modes
instantaneous sampling and frame-by-frame accumulation of the information from the camera. Results of
numerical experiments are presented.
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Based on the analysis of factors that influence atmospheric imaging over long turbulent horizontal paths, we
consider a number of practical configurations of opto-electronic surveillance systems with optimized performance.
Our approach is based on simultaneous quasi real-time processing of a number of images obtained through
uncorrelated atmospheric paths, using either temporal or spatial multiplexing. Practical results obtained on a
4.25 km imaging path using newly developed imaging system, based on temporal multiplexing, combined with
image restoration based on projection on convex sets, are reported. Potential applications include optical and
IR long-range security and military surveillance, unmanned aircraft imaging systems and naval optical imaging
and warning systems.
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We are considering of new devices for solar astronomical telescope as a tools for adaptive optics correction. One of
them is a high precision Shack-Hartmann wave-front sensor has been developed on the basis of a low-aperture offaxis
diffraction lens array. The second device is image quality analyzer. Efficiency of the adaptive optical in system
of the imaging is valued by quality of the updated image.
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Large and lightweight primary mirrors of high optical quality are considered to be a key element of next generation
deployable space telescopes. In this paper we present a membrane mirror demonstrator and show experimental results of
the associated mechanical and optical characteristics. The mounting conditions of such a membrane mirror cause static
optical aberrations which are compensated as a proof of principle using an adaptive mirror and a metric optimizationbased
control system. The feasibility of the complete system for receiving and transmitting applications will be
discussed.
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We will present results for new object spectrum phasor reconstruction methods in speckle imaging. Each phasor
reconstruction algorithm results from minimizing a very naturally defined weighted-least-squares error function. Once
we pick a phasor-based error function, the remaining steps in our algorithms are developed by setting the error function
variation, with respect to each phasor element, to zero. The resulting coupled nonlinear equations for the minimum error
phasor array are then solved iteratively, locating the error function minimum. In these applications, we will specifically
compare and contrast three implementations: 1) Knox-Thompson; 2) bispectrum, using two unit-shift bispectrum planes;
3) bispectrum, using four bispectrum planes. Although we develop and minimize error functions for three specific singleaperture
speckle methods, the approach readily generalizes to other cases.
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In this paper we introduce a technique to correct atmospheric turbulence. The characteristic of this promising procedure
is that the distorted wavefront is corrected without any information about the wavefront itself. This technique relies on
the combined use of a deformable mirror controlled by a Stochastic Parallel Gradient Descent (SPGD) algorithm and an
image quality measurement. Even though this procedure is in terms of time slower than a direct wavefront
reconstruction, it appears that compared to conventional AO systems the problems related to scintillations are noticeably
reduced.
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The degree of image degradation due to atmospheric turbulence is particularly severe when imaging over long horizontal
paths since the turbulence is strongest close to the ground. The most pronounced effects include image blurring and
image dancing and in case of strong turbulence image distortion as well. To mitigate these effects a number of methods
from the field of image processing have been proposed most of which aim exclusively at the restoration of static scenes.
But there is also an increasing interest in advancing turbulence mitigation to encompass moving objects as well.
Therefore, in this paper a procedure is described that employs block-matching for the segmentation of static scene
elements and moving objects such that image restoration can be carried out for both separately. This way motion blurring
is taken into account in addition to atmospheric blurring, effectively reducing motion artefacts and improving the overall
restoration result. Motion-compensated averaging with subsequent blind deconvolution is used for the actual image
restoration.
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Coherent beam combining (CBC) of fiber array is a promising way to generate high power and high quality laser beams.
Target-in-the-loop (TIL) technique might be an effective way to ensure atmosphere propagation compensation without
wavefront sensors. In this paper, we present very recent research work about CBC of collimated fiber array using TIL
technique at the Key Lab on Adaptive Optics (KLAO), CAS. A novel Adaptive Fiber Optics Collimator (AFOC)
composed of phase-locking module and tip/tilt control module was developed. CBC experimental setup of three-element
fiber array was established. Feedback control is realized using stochastic parallel gradient descent (SPGD) algorithm.
The CBC based on TIL with piston and tip/tilt correction simultaneously is demonstrated. And the beam pointing to
locate or sweep position of combined spot on target was achieved through TIL technique too. The goal of our work is
achieve multi-element CBC for long-distance transmission in atmosphere.
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We propose a novel wavefront sensing technique based on binary-aberration-mode filtering and detection. Rather than
Zernike polynomials, the orthogonal binary two-dimensional Walsh functions are transferred to circular mode-fieldfitted
Walsh functions and used as binary aberration modes to expand the wavefront. A Digital Micromirror Device
(DMD) is employed as an intensity spatial light modulator (SLM). It generates each of the intensity modulation patterns
prescribed by the mode-field-fitted Walsh functions to modulate the intensity of the incident beam before it is focused to
impinge on a single-mode optical fiber. The single-mode optical fiber, as a spatial mode filter, supports only fundamental
binary aberration mode. A detector collects the amount of the intensity after each modulation. By building the
relationship with the intensity, the binary-aberration-mode coefficients can be calculated. This technique turns the
complex two-dimensional wavefront sensing into simple intensity detection. Therefore, many limitations, such as low
response frequency and weak far-infrared detection capability of most photosensor arrays can be easily eliminated just
by adopting a photosensor such as a photodiode. Thus, this technique is especially suitable for weak and far-infrared
light detection. The numerical simulation demonstrates that the wavefront reconstruction with the binary aberration
modes is reliable and the technique can easily meet the demands of high speed atmospheric measurements and has a
promising application in atmospheric fields.
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