Laser Aided Detection and Ranging (LADAR) imaging systems can be used to provide high resolution
imaging and tracking of moving targets at night. Central to the tracking system is a high speed correlation
algorithm to determine target motion between sensor image frames. Several issues complicate the
correlation calculations. These include coherent speckle noise and atmosphere induced scintillation of the
illuminator beam. The Fitts correlation algorithm is commonly used because of its simplicity and speed.
However it is only optimal when the shift between sensor frames is less than a pixel. In addition it can be
sensitive to certain types of noise. Projection based phase only (PBPO) is another type of correlation
algorithm that is also high speed and in many cases less sensitive to noise. In this paper we compare the
Fitts algorithm with PBPO in terms of number of computations and noise immunity when used in a
LADAR tracker.
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.
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.
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.
Airglow luminescence in the SWIR region due to upper atmospheric recombination of solar excited molecules is a
well accepted phenomenon. While the intensity appears broadly uniform over the whole sky hemisphere, we are
interested in variations in four areas: 1) fine periodic features known as gravity waves, 2) broad patterns across the
whole sky, 3) temporal variations in the hemispheric mean irradiance over the course of the night, and 4) long term
seasonal variations in the mean irradiance. An experiment is described and results presented covering a full year of
high resolution hemispheric SWIR irradiance images. An automated gimbal views 45 hemispheric positions, using
30 second durations, and repeats approximately every half hour through out the night. The gimbal holds co-mounted
and bore-sighted visible and SWIR cameras. Measuring airglow with respect to spatial, temporal, and seasonal
variations will facilitate understanding its behavior and possible benefits, such as night vision and predicting upper
atmosphere turbulence. The measurements were performed in a tropical marine location on the island of Kauai Hi.
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. By examining images in an urban and a rural setting, we investigate the
correlation between the appearances of passive dark of night images in the SWIR with NIR- visible. The
experimental setup consists of two sensors, a NIR-visible CCD and an InGaAs array sensitive in the SWIR, both colocated
on an AZ-EL mount, and both co-boresighted so that different viewing angles of the sky and terrestrial
scenes are possible. By making corrections for focal length and pixel size, the visible and SWIR data can be
compared. After taking several nights of data in the urban environment of Albuquerque, NM, the entire system was
then re-located to a rural location on the island of Kauai in a rural setting with very low ambient light. It is shown
that under most conditions the SWIR sensor produces significantly better imagery using the airglow illumination
source.
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 of wave
length 0.9 to 1.7 μm. Numerous studies of these phenomena have demonstrated that the irradiance shows significant
temporal and spatial variations in the night sky. Changes in weather patterns, seasons, sun angle, moonlight, etc
have the propensity to alter the SWIR air glow irradiance pattern. By performing multiple SWIR measurements a
mosaic representation of the celestial hemisphere was constructed and used to investigate these variations over time
and space. The experimental setup consisted of two sensors, an InGaAs SWIR detector and a visible astronomical
camera, co-located and bore sighted on an AZ-EL gimbal. This gimbal was programmed to view most of the sky
using forty five discrete azimuth and elevation locations. The dwell time at each location was 30 seconds with a
total cycle time of less than 30 minutes. The visible astronomical camera collected image data simultaneous with
the SWIR camera in order to distinguish SWIR patterns from clouds. Data was reduced through batch processing
producing polar representations of the sky irradiance as a function of azimuth, elevation, and time. These spatiotemporal
variations in the irradiance, both short and long term, can be used to validate and calibrate physical models
of atmospheric chemistry and turbulence. In this paper we describe our experimental setup and present some results
of our measurements made over several months in a rural marine environment on the Island of Kauai Hawaii.
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 has been demonstrated as an effective illumination source for 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 air glow region. These spatiotemporal
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. We are interested in
studying these phenomena for a variety of reasons. First they can give an insight into upper atmospheric physics,
second we would like to understand the variations in order to determine if air glow can be used as a reliable
illumination source for night time terrestrial imaging. To that end we have been collecting data on ground
irradiance from air glow over the past six months at a site on the island of Kauai. The purpose of this paper is to
discuss some initial analysis of this data.
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 has been demonstrated as an effective illumination source for 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 sky glow region. These spatiotemporal
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. Ground to space
observation systems especially those employing adaptive optics are adversely affected by high altitude turbulence
and winds. In this paper we propose the use of sky glow observations to predict and characterize image system
degradation due to upper atmosphere turbulence.
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 of wave
length 0.9 to 1.7 μm. Numerous studies of these phenomena have demonstrated that the irradiance shows significant
temporal and spatial variations in the night sky. Changes in weather patterns, seasons, sun angle, moonlight, etc
have the propensity to alter the SWIR air glow irradiance pattern. By performing multiple SWIR measurements a
mosaic representation of the celestial hemisphere was constructed and used to investigate these variations over time
and space. The experimental setup consisted of two sensors, an InGaAs SWIR detector and a visible astronomical
camera, co-located and bore sighted on an AZ-EL gimbal. This gimbal was programmed to view most of the sky
using forty five discrete azimuth and elevation locations. The dwell time at each location was 30 seconds with a
total cycle time of less than 30 minutes. The visible astronomical camera collected image data simultaneous with
the SWIR camera in order to distinguish SWIR patterns from clouds. Data was reduced through batch processing
producing polar representations of the sky irradiance as a function of azimuth, elevation, and time. These spatiotemporal
variations in the irradiance, both short and long term, can be used to validate and calibrate physical models
of atmospheric chemistry and turbulence. In this paper we describe our experimental setup and present some results
of our measurements made over several months in a rural marine environment on the Islands of Kauai and Maui
Hawaii.
Kristin Nixon, Robert Rowe, Jeffrey Allen, Steve Corcoran, Lu Fang, David Gabel, Damien Gonzales, Robert Harbour, Sarah Love, Rick McCaskill, Bob Ostrom, David Sidlauskas, Karen Unruh
This paper describes a new biometric technology based on the optical properties of skin. The new technology can perform both identity verification and sample authenticity based on the optical properties of human skin. When multiple wavelengths of light are used to illuminate skin, the resulting spectrum of the diffusely reflected light represents a complex interaction between the structural and chemical properties of the skin tissue. Research has shown that these spectral characteristics are distinct traits of human skin as compared to other materials. Furthermore, there are also distinct spectral differences from person to person. Personnel at Lumidigm have developed a small and rugged spectral sensor using solid-state optical components operating in the visible and very near infrared spectral region (400-940nm) that accurately measures diffusely reflected skin spectra. The sensors are used for both biometric determinations of identity as well as the determination of sample authenticity. This paper will discuss both applications of the technology with emphasis on the use of optical spectra to assure sample authenticity.
A 941 channel, 1500 Hertz frame rate adaptive optical (AO) system has been installed and tested in the coude path of the 3.5m telescope at the USAF Research Laboratory Starfire Optical Range. This paper describes the design and measured performance of the principal components comprising this system and present sample results from the first closed-loop test of the system on stars and an artificial source simulator.
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