PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.
Advanced weaponry is providing an exponential increase in intelligence data collection capabilities and the
Intelligence Community (IC) is not properly positioned for the influx of intelligence supportabilitiy requirements the
defense acquisition community is developing for it. The Air Force Material Command (AFMC) has initiated the
Intelligence Supportability Analysis (ISA) process to allow the IC to triage programs for intelligence sensitivities as
well as begin preparations within the IC for the transition of future programs to operational status. The ISA process
is accomplished through system decomposition, allowing analysts to identify intelligence requirements and
deficiencies. Early collaboration and engagement by program managers and intelligence analysts is crucial to the
success of intelligence sensitive programs through the utilization of a repeatable analytical framework for evaluating
and making cognizant trade-offs between cost, schedule and performance. Addressing intelligence supportability
early in the acquisition process will also influence system design and provide the necessary lead time for intelligence
community to react and resource new requirements.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
In coded aperture imaging, adaptive masks provide significant benefit, notably for their role in supporting
the image recovery process. Each discrete mask pattern produces a unique point spread function on the
detector array, which can be used to enhance the resolution of imagery and indeed to enable tracking on a
sub-pixel basis. The choice of adaptive mask technology is very dependent on both the spectral region of
interest and the configuration of the coded aperture camera. Transmissive masks can be based on liquid
crystal, micro-machined air-spaced Fabry-Perot cavities or even phase-change materials, whilst reflective
masks can be based on liquid crystal on silicon (LCOS) or MEMS tip-tilt mirrors. Such components can
also provide the basis for discriminative imaging. This paper provides a review of the various technologies
and assesses performance levels in relation to different applications.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
We introduce the linear system transfer matrix H as a means to interpret classical optical sensing, such as
imaging and spectroscopy, and new computational sensing. This representation allows us to identify PSF
engineering and multiplexed measurements as duals of each other. We also consider several new computational
sensing systems and identify the corresponding system matrix.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
The design and implementation of adaptive coded apertures (diffraction) has advanced significantly since the first SPIE
conference on Adaptive Coded Aperture Imaging and Non-Imaging Sensors held in 2007. Core algorithmic concepts
relating to coding and decoding techniques remain steeply based in its non-diffractive design origins. We discuss
adaptive coded aperture imaging's current capabilities in light of recent advances as well as methods of improvement for
future systems design. The advantages of implementing reconfigurable mask patterns compared to fixed ones will also
be discussed, as well as potential improvement in angular resolution by means of reconfigurable masks.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
Imaging and Non-Imaging Diffraction System Concepts
Adaptive coded aperture imaging (ACAI) has the potential to enhance greatly the performance of sensing systems by
allowing sub detector pixel image and tracking resolution. A small experimental system has been set up to allow the
practical demonstration of these benefits in the mid infrared, as well as investigating the calibration and stability of the
system. The system can also be used to test modeling of similar ACAI systems in the infrared. The demonstrator can use
either a set of fixed masks or a novel MOEMS adaptive transmissive spatial light modulator. This paper discusses the
design and testing of the system including the development of novel decoding algorithms and some initial imaging
results are presented.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
Coded aperture imagery poses a challenge for traditional image tracking algorithms because of the highly distributed
nature of the coded imagery. Traditional algorithms would require this imagery to undergo a computationally expensive
decoding operation before subsequent processing and tracking. In this paper, a novel tracking algorithm is described that
can track point-source targets at sub-pixel accuracy without requiring the coded aperture imagery to be decoded.
Furthermore, it is shown that the algorithm is robust to changes in the coded aperture mask pattern, and so is suitable for
use in adaptive coded aperture imaging systems. Some results of the algorithm on synthetic and initial MWIR
experimental data will be given.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
Static Feature-specific imaging (SFSI) employing a fixed/static measurement basis has been shown to achieve
superior reconstruction performance to conventional imaging under certain conditions.1-5 In this paper, we
describe an adaptive FSI system in which past measurements inform the choice of measurement basis for future
measurements so as to maximize the reconstruction fidelity while employing the fewest measurements. An
algorithm to implement an adaptive FSI system for principle component (PC) measurement basis is described.
The resulting system is referred to as a PC-based adaptive FSI (AFSI) system. A simulation study employing the
root mean squared error (RMSE) metric to quantify the reconstruction fidelity is used to analyze the performance
of the PC-based AFSI system. We observe that the AFSI system achieves as much as 30% lower RMSE compared
to a SFSI system.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
Coded Aperture Imaging (CAI) is a new approach to system design whereby the optics are simplified in a controlled way
so that system performance can be recovered using appropriate computer based algorithms. Adopting Coded Aperture
approaches to sensor designs opens up possibilities of increasing the system design trade-space thereby giving the system
designer greater degrees of freedom to optimise the system. A comparison has been made between a system adopting CA
in its optical train with systems based on conventional optics approaches. These comparisons show that CA based
systems can provide significant benefits to the user in some applications.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
The use of hybrid optical-digital techniques facilitates improved optimisation of imaging systems. It involves the
combined use of optical coding of an image using pupil-plane phase-modulation of the transmitted wavefront and postdetection
digital decoding. Previous research in hybrid imaging tends to emphasize constancy of the modulation transfer
function with aberrations and ignore the significant variations in the phase transfer function. We show that the
restoration artefacts introduced by phase mismatch effects can also be used to deduce the defocus PSF, and when this is
achieved, an overall improvement in image quality can be attained. Both numerical simulations and experimental
images of hybrid imaging systems are presented.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
We have previously reported the use of coded aperture for the design of wide area imaging sensors.
Such sensors can allow the rate and resolution of the sensed information to be controlled by varying
the sequence of codes used to acquire and reconstruct the data. However, since sensor resources are
finite, it is essential to develop a framework for optimizing their allocation with respect to dynamic
scene content over a large area. In this paper, we discuss an approach for achieving this using the
principle of highly optimized tolerance (H.O.T) [1] which provides a theoretical basis for allocating
resources in response to events to minimize a user defined loss function. Some results of initial
simulations are presented to illustrate the concept.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
For many years, the basic goal of sparse aperture design has been to maximize the support of the
modulation transfer function (MTF). Golay apertures and related nonredundant arrays are typically
used to achieve this objective. Unfortunately, maximizing the support of the MTF has the necessary
effect of decreasing the magnitude of the MTF at mid-band spatial frequencies. Fienup has shown
that the decreased magnitude of the MTF for nonredundant arrays contributes as much as reduced
throughput to the loss of SNR in sparse apertures relative to full aperture systems. This paper
considers the use of periodic sparse arrays to improve the mid-band MTF at the cost of reduced
spatial frequency coverage. We further consider methods to recover lost spatial frequencies using
multispectral and multiframe sampling and decompressive inference.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
Adaptive coded aperture (diffraction) sensing, an emerging technology enabling real-time, wide-area IR/visible sensing
and imaging, could benefit from new high performance biologically inspired image processing architectures. The
memristor, a novel two terminal passive device can enable significantly powerful biologically inspired processing
architectures. This device was first theorized by Dr. Leon Chua in 1971. In 2008, HP Labs successfully fabricated the
first memristor devices. Due to its unique properties, the memristor can be used to implement neuromorphic functions as
its dynamics closely model those of a synapse, and can thus be utilized in biologically inspired processing architectures.
This paper uses existing device models to determine how device parameters can be tuned for the memristor to be used in
neuromorphic circuit design. Specifically, the relation between the different models and the number of states the device
can hold are examined.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
Two major missions of Surveillance systems are imaging and ground moving target indication (GMTI). Recent advances in
coded aperture electro optical systems have enabled persistent surveillance systems with extremely large fields of regard.
The areas of interest for these surveillance systems are typically urban, with spatial topologies having a very definite
structure. We incorporate aspects of a priori information on this structure in our aperture code designs to enable optimized
dealiasing operations for undersampled focal plane arrays. Our framework enables us to design aperture codes to minimize
mean square error for image reconstruction or to maximize signal to clutter ratio for GMTI detection. In this paper we
present a technical overview of our code design methodology and show the results of our designed codes on simulated
DIRSIG mega-scene data.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
Coded aperture imaging has been used for astronomical applications for several years. Typical implementations used a
fixed mask pattern and are designed to operate in the X-Ray or gamma ray bands. Recently applications have emerged in
the visible and infra red bands for low cost lens-less imaging systems and system studies have shown that considerable
advantages in image resolution may accrue from the use of multiple different images of the same scene - requiring a
reconfigurable mask.
Previously reported work focused on realising a 2x2cm single chip mask in the mid-IR based on polysilicon micro-optoelectro-
mechanical systems (MOEMS) technology and its integration with ASIC drive electronics using conventional
wire bonding. It employs interference effects to modulate incident light - achieved by tuning a large array of asymmetric
Fabry-Perot optical cavities via an applied voltage and uses a hysteretic row/column scheme for addressing.
In this paper we report on the latest results in the mid-IR for the single chip reconfigurable MOEMS mask, trials in
scaling up to a mask based on a 2x2 multi-chip array and report on progress towards realising a large format mask
comprising 44 MOEMS chips. We also explore the potential of such large, transmissive IR spatial light modulator arrays
for other applications and in the current and alternative architectures.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
Adaptive coded aperture imaging systems can resolve objects that are smaller than the pixel-limited resolution of the
detector focal plane array. This is done by combining multiple frames of data, where different frames are taken with
different coding patterns on the coded-aperture mask. In the mid-wave infrared the required signal to noise ratio
necessitates some form of light concentration. Optical design software has been used to model candidate optical systems
with the aim of achieving up to four times resolution enhancement along each linear dimension. As in some other
computational imaging systems, the requirements on the optical system are found to be different to those that are
normally used in more classical optical designs. The basic needs are a point-spread function of suitable extent that
changes gradually with angle and does not vary significantly with the expected changes in input spectra or system
temperature. Novel metrics have been derived and used to inform the optical design. The modeling and design trade-offs
and resulting performance are discussed.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
Coded aperture imaging technology have been utilized [1] for imaging in various space missions primary associated
with X-Ray and Gamma ray sources. The need to extend the coded aperture technique into Visible/IR is pushing the
technology and so geometrical features become smaller [2,3]. As the geometrical feature become smaller, second
order effect such as diffraction become noticeable. The effects are typically isolated in order to improve Signal-to-
Noise Ratio (SNR). In this paper we are exploiting diffraction and interference to use as a coding approach. We
propose a coded aperture transmitter/receiver system capable of hiding information (bits) inside the diffraction nulls.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
The memristor, experimentally verified for the first time in 2008, is one of four fundamental passive circuit elements (the
others being resistors, capacitors, and inductors). Development and characterization of memristor devices and the design
of novel computing architectures based on these devices can potentially provide significant advances in intelligence
processing systems for a variety of applications including image processing, robotics, and machine learning. In
particular, adaptive coded aperture (diffraction) sensing, an emerging technology enabling real-time, wide-area
IR/visible sensing and imaging, could benefit from new high performance biologically inspired image processing
architectures based on memristors. In this paper, we present results from the fabrication and characterization of
memristor devices utilizing titanium oxide dielectric layers in a parallel plate conuration. Two versions of memristor
devices have been fabricated at the University of Dayton and the Air Force Research Laboratory utilizing varying
thicknesses of the TiO2 dielectric layers. Our results show that the devices do exhibit the characteristic hysteresis loop in
their I-V plots.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
In this paper we investigate coded apertures as a function of mask damage, cross talk (on the focal plane arrays), and combinations of the two. We apply a Monte Carlo simulation to extract the probability of the scene reconstruction vs SNR as a performance metric. In addition we calculate the mean time between failures of the system as function damage to the mask.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
We report a tentative interferometric detection of an earth-orbiting artificial satellite using optical interferometry. We
targeted four geosynchronous communications satellites with the Navy Prototype Optical Interferometer (NPOI) near
Flagstaff, AZ, and obtained interferometric fringes on one of them, DIRECTV-9S. We used an east-west 15.9-meter
baseline of the NPOI and took data in 16 spectral channels covering the 500-850 nm wavelength range. Observations
took place during the "glint season" of 28 February to 3 March 2008, when the geometry of the solar panel arrays and the
Sun's position creates glints as bright as 2nd magnitude of a few minutes' duration each night. We detected fringes on
the satellite at approximately the 2 σ level on 1 March at magnitude 4.5. Subsequent analysis shows that the fringe
amplitudes are consistent with a size scale of 2 meters (50 nanoradians at geosynchronous orbit) in an east-west
direction. This detection shows that interferometric detection of satellites at visual wavelengths is possible, and suggests
that a multi-baseline interferometer array tailored to the angular size and brightness of geosynchronous satellites could
lead to images of these satellites.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
Intensity interferometry utilizes measurements of the squared-magnitude of the Fourier transform of an object using
relatively simple, phase-insensitive hardware, and therefore holds the promise of extremely high spatial resolution in
astronomy and various branches of physics. However, this promise has not been realized due to signal-noise-ratio
(SNR) issues and due to the maturity of image recovery algorithms. To recover an image, the phase of the Fourier
transform must be determined in addition to its magnitude. In a recent paper, relatively good one-dimensional (1-D)
image recoveries were obtained with a fast non-iterative algorithm utilizing the Cauchy-Riemann relations and a mild
constraint on the symmetry of the object. In this paper, the approach is extended to two spatial dimensions by
combining multiple 1-D reconstructions, and ensuring mutual consistency between 1-D slices. Mutual consistency is
enforced using several different approaches, including phase retrieval. This use of the Cauchy-Riemann approach
combined with imposition of mutual consistency is found to reduce noise sensitivity significantly. Three approaches are
evaluated for image quality for different objects using sparse Fourier-plane sampling, showing good reconstruction of
images at SNR's as low as 7 at the origin in the Fourier plane (and thus even lower SNR's at higher angular
frequencies).
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
The purpose of this paper is to develop adaptive optics system which estimates degrading factors using observed images
and automatically compensates the distorted wavefronts using a spatial light modulator (SLM). The system estimates
optical wavefront aberrations by phase diversity method. The SLM which is used for wavefront compensation applies
multiple time-series known wavefronts as a priori information to the optical system. By using the SLM for the phase
diversity generator, it is possible to select the optimal number and shape of phase diversities for various kinds of natural
modes of wavefront aberrations which are represented by the Zernike polynomials. In laboratory test, wavefront
aberrations were generated by optical misalignments, and they were estimated as the coefficients of Zernike polynomials
for an extended scene. The suggested method was validated by numerical simulations and laboratory tests. The high
estimation accuracy of the distorted wavefront was demonstrated, and nearly diffraction limited images were acquired by
wavefront compensation.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
In a coherent LADAR system, the spatial coherent performance of the return signal will be affected by the
scattering of target object and atmospheric effect, which thus has influence on the mixing efficiency, Singal-to-noise
ratio and receiving field of view. Since the practical wave front correlation of return signal beam is complex for
coherent LADAR, here we will confine ourselves to a simple model that the return signal field has uniform distributed
irradiance and is partially coherent, and the local oscillator beam adopts a Gauss mode. In this paper we research the
variance of the mixing efficiency, signal-to-noise ratio and field of view with the influence of the signal spatial
coherence width and collecting aperture radius, and give some guiding suggestions on the design of heterodyne
receiver for coherent LADAR .
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
A demonstrator of synthetic aperture imaging ladar (SAIL) is constructed with the maximum aperture Ø300mm of
antenna telescope. This demonstrator can be set with a rectangular aperture to produce a rectangular footprint suitable for
scanning format with a high resolution and a wide strip. Particularly, the demonstrator is designed not only for the farfield
application but also for the verifying and testing in the near-field in the laboratory space. And a 90 degree optical
hybrid is used to mitigate the external phase errors caused by turbulence and vibration along line of sight direction and
the internal phase errors caused by local fiber delay line. This paper gives the details of the systematic design, and the
progresses of the experiment at a target distance around 130m.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
In this paper, a concept of spotlight-mode incoherently-synthetic aperture imaging ladar (SAIL) is proposed on the basis
of computer tomography (CT). This incoherent SAIL has three operations of conventional, inverse and CT
spotlight-modes with two sensing techniques of range and Doppler resolutions, and supplies a variety of dimensional
transformations for 2-D range- and Doppler-resolved imaging of 2-D objects and for 3-D range-resolved imaging or in
the depth compressed 2-D range- and Doppler-resolved imaging of 3-D objects. Due to the simplification in both the
construction and the algorithm the difficulties in the signal collection and data processing are importantly relaxed. The
incoherent SAIL provides a great potential for applications in the extensive fields. The paper gives the detailed analysis.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
Miniature inexpensive neon indicator lamp plasma glow discharge detectors (GDD) are excellent candidates to serve as
room temperature, low cost, terahertz (THz) radiation detectors and as pixels in THz imaging systems.
Heterodyne amplification of low power signals via higher power reference beams is very important for THz imaging
systems because it permits detection of much lower object beam intensities. An experimental result of 300GHz
heterodyne detection by a single commercial GDD device costing about 30 cents is presented here. In heterodyne image
detection a picture is taken of interference fringes or a hologram deriving from a coherent reference wave and a coherent
wave reflected from or transmitted through an object. Transmission with in-line or zero angles between those two waves
is important to widen the fringes. The GDD detector is transparent, so that it's possible to receive radiation from both
sides, at 0 and 180 degree. This permit receiving the wave reflected from or transmitted through an object at 0 degree
and the reference wave from the opposite direction at 180 degree. Such interference fringe widening can permit
heterodyne direct imaging of the object instead of imaging the interference pattern.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
Correlography is a technique that allows image formation from non-imaged speckle patterns via their relationship to the
autocorrelation of the scene. Algorithms designed to form images from this type of data represent a particular type of
phase retrieval algorithm since the autocorrelation function is related to the Fourier magnitude of the scene but not the
Fourier phase. Methods for forming 2-D images from far field intensity measurements have been explored previously,
but no 3-D methods have been put forward for forming range images of a scene from this kind of measurement. Farfield
intensity measurements are attractive large focusing optics are not required to form images. Pupil plane intensity
imaging is also attractive due to the fact that the effects of atmospheric turbulence close to the imaging system are
mitigated by the cancelation of phase errors in the intensity operation.
This paper suggests a method for obtaining 3-D images of a scene through the use of successive 2-D pupil plane
intensity measurements sampled with an APD (Avalanche Photo-Diode) array. The 2-D array samples the returning
pulse from a laser at a fast enough rate to avoid aliasing of the pulse shape in time. The spatial pattern received by the
array allows the Autocorrelation of the scene to be determined as a function of time. The temporal autocorrelation
function contains range information to each point in the scene illuminated by the pulsed laser. The proposed algorithm
uses a model for the LADAR pulse and its relation to the autocorrelation of the scene as a function of time to estimate
the range to every point in the reconstructed scene assuming that all surfaces are opaque (meaning a second return from
the same point in the scene is not anticipated). The method is demonstrated using a computer simulation.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
A new method of high resolution laser imaging is developed in this paper, which is denoted as Fresnel telescopy. It
creates Fresnel zone plate (FZP) fringe at the detected target, then makes relative motion between Fresnel zone plate and
the target to accomplish the encoding process, namely, to achieve the convolution between target reflection function and
the Fresnel zone plate intensity distribution function. The design scheme of the proposed system is presented. The
proposed technique offers significant practical benefit for ground-based imaging of objects in many important military
applications.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
A control software experiment system of synthetic aperture imaging ladar is developed based on multithreading parallel
mechanism of Labview8.6 and SCPI (standard commands for programmable instruments) protocol. Firstly, hardware
composition and software function requirement of the system are analyzed. Then, the control module of the laser and
stepper motor and the data communication module of oscillograph are developed separately and the three modules are
integrated to realize the gather and compute of the return signal. Finally, by the result of experiment, the control software
worked steady and real timely and it can operate the laser, stepper motor and oscillograph successfully.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.