This PDF file contains the front matter associated with SPIE Proceedings Volume 7094, including the Title Page, Copyright information, Table of Contents, Introduction (if any), and the Conference Committee listing.

The lateral resolution of an imaging system is limited by its numerical aperture and the wavelength. Structured illumination incident on the object heterodynes the higher spatial frequencies of the object with the spatial frequency of the sinusoidal illumination into the passband of the imaging system providing lateral superresolution. This idea has been implemented in microscopy. Multiple images of an object are taken, with distinct phase shifts in the sinusoidally patterned illumination. They are processed to separate the conventional, un-aliased object spatial frequencies from the aliased ones, which contain superresolution information. The separated aliased terms are de-aliased (i.e. the spatial frequencies in them are moved to their correct locations in Fourier space) giving superresolution along the direction perpendicular to the orientation of the sinusoidal fringe pattern. This process is repeated with, say, 60° and 120° rotation of the sinusoidal fringe illumination to obtain superresolution in all directions. The final reconstructed image can be obtained by appropriate combination of the de-aliased superresolution components with the conventional, un-aliased components. We discuss the signal-to-noise ratio (SNR) and optical transfer function (OTF) compensation in the combination of all these components to obtain an image with lateral superresolution.

We have developed a computer simulation to demonstrate the use of a periodic grating structure in the near field of a telescope to super-resolve objects in the far field. The separation between the telescope pupil and the grating provides a periodic anisoplanatism for the telescope, modulating the measured brightness of a point source as it moves across the field normal to the grating. The resulting periodic modulation of an extended source can thus produce a spatial frequency heterodyning effect, where frequency components outside the diffraction passband are aliased inside the passband and measured. Using the simulation, we have quantitatively validated the analytically-predicted periodic blur function for the case of single near-field grating. Further, we have shown the heterodyning effect is observed when the distance between the grating and pupil corresponds to the Talbot distance, where the grating forms a "self-image" in the plane of the pupil.

Phase errors introduced in the object beam of a digital hologram degrade the image quality of the object. We present computer simulations showing the effect of multiple planes of phase errors in the propagation path. By using a nonlinear optimization technique to maximize sharpness metrics, we show results that account for aberrations in multiple planes and correct anisoplanatic blur. This paper demonstrates this technique for two and three phase screens.

Space imaging has many uses, including military intelligence, commercial map making, and natural resource management. The desire for higher resolution and its natural limit due to diffraction has increasingly pushed up the size and expense of space platforms. An alternative to larger telescopes is to use advanced image reconstruction and modern small pixel detectors to build extremely compact satellites that can produce sub-diffraction resolution images. Because of the Pixon® method's use of minimum complexity image modeling, it is especially good at recovering spatial frequencies beyond the diffraction cutoff. This is because the simplest model that fits the spatial frequencies present in the image, i.e., those below the diffraction cutoff, must necessarily contain correct spatial frequencies beyond the diffraction cutoff. In our work with the Pixon method we have routinely obtained images with 1/4 diffraction resolution for well sampled data (~4 pixels per diffraction FWHM) with good signal-to-noise ratio (~a few hundred per resolution element). With such capabilities a 3.0 meter focal length, 0.8 meter diameter telescope, launched with a Pegasus missile would have an effective 0.1 meter ground sampling distance, i.e., NIIRS 9 performance, from a 400 km orbit (675 nm operating wavelength). We present a number of examples demonstrating the practical capabilities of the Pixon method for achieving these goals.

Successful fusion combines salient features of each image to produce a new fused image with more "information". Although different sensors have different spatial resolutions, they tend to be detector-limited and this usually does not significantly affect fusion. The biggest problem with sensor fusion is that the number of detectors on each array is different. If the number of pixels on target are made equal (the desired design), then the fields-of-view are different. This may affect operational effectiveness. If the fields-of-view are equal, then pixels on target are different. This accentuates phasing effects, increases target edge ambiguity, and overall makes fusion more difficult. Sampling artifacts are most noticeable with man-made objects and are pronounced with periodic targets (bar targets).

In any image post-processing system, an imperfect knowledge of the system point-spread function (PSF) leads to errors in the estimation of the truth image from the image data. Here we treat the problem of PSF uncertainty resulting from either uncorrected or partially corrected atmospheric turbulence related phase errors and its impact on image estimation in the presence of Poisson count statistics.

In recent work, the resolution limits of two variations of chromo-tomographic hyperspectral imaging sensors were discussed. In this paper, we examine another variation of this type of hyperspectral sensor the present a reconstruction method using computed tomography to estimate a hyperspectral data cube and examine the limits of resolution. The resolution analysis is then compared with a simulation to determine the validity of the calculated resolution bounds. The simulation setup is discussed and results are presented.

Remote Ultra-Low Light Imaging detectors are photon limited detectors developed at Los Alamos National Laboratories. RULLI detectors provide a very high degree of temporal resolution for the arrival times of detected photoevents, but saturate at a photo-detection rate of about 10⁶ photo-events per second. Rather than recording a conventional image, such as output by a charged coupled device (CCD) camera, the RULLI detector outputs a data stream consisting of the two-dimensional location, and time of arrival of each detected photo-electron. Hence, there is no need to select a specific exposure time to accumulate photo-events prior to the data collection with a RULLI detector - this quantity can be optimized in post processing. RULLI detectors have lower peak quantum efficiency (from as low as 5% to perhaps as much as 40% with modern photocathode technology) than back-illuminated CCD's (80% or higher). As a result of these factors, and the associated analyses of signal and noise, we have found that RULLI detectors can play two key new roles in SSA: passive imaging of exceedingly dim objects, and three-dimensional imaging of objects illuminated with an appropriate pulsed laser. In this paper we describe the RULLI detection model, compare it to a conventional CCD detection model, and present analytic and simulation results to show the limits of performance of RULLI detectors used for SSA applications at AMOS field site.

Airglow due to upper atmospheric molecular emissions has been known since the late 1960's. Recent interest in extending high altitude low light imaging capability has created an interest in exploiting the airglow phenomenon. We discuss the feasibility of developing a sensor that operates above the atmospheric layer responsible for airglow. We examine the implications to the design of the focal plane array and electronics caused by viewing the ground through the radiant layer.

We are engaged in the development of an FPGA-based real-time video Deblurring Anisoplanaticism Corrector (DAC) under a U.S. Army SBIR Phase II program. This DAC processor features the ability to measure and correct for the inherent geometric image warp (e.g. as caused by anisoplanaticism) for each incoming video field by comparison with a running-average reference image compiled by the processor from recent accumulated image data. The incoming video field is accordingly dewarped and passed to an adaptive higher-order temporal filter, which appropriately combines the new video field into the reference image. This filter moderates the contribution of each new pixel, based on temporal spectrum, goodness of fit, and related information, in order to differentiate between the effects of anisoplanatically induced warp and the effects of true changes in the image such as those caused by motion of objects. The DAC processor also includes other real-time PixonVision image enhancement capabilities such as dehazing, spatial deblurring for removal of additional high-order image blur, spatial denoising, and spatially adaptive contrast enhancement. A hardware proof-of-concept system is being implemented for standard NTSC video operation, and development progress and related preliminary results for that system are presented here.

It is shown that although divergent upon exiting an optical solid, and typically color dispersive over short propagation distances, controllably generated ultra broadband continuums can be propagated as a pulsed white-light source with a near-ideal Gaussian intensity distribution. In contrast to active 3-D imagery with monochromatic illumination, pulsed ultra-broadband continuum illumination is shown to enable active 3-D multi/hyperspectral imaging and sensing for standoff characterization of materials and enhanced object identification.

For synthetic aperture ladar (SAL) imaging, there are difficulties in the space domain because the size of optical antenna of telescope is up to six orders of magnitude larger than the wavelength. In this paper, we suggest a defocused and spatial phase masked telescope for reception to compensate the diffraction aberration from the target to match the directivity of heterodyne detection, a defocused and phase masked transmission telescope to send out a wavefront with an additional and controllable spatial quadratic phase to the phase history, and a circulated duplex to compensate the aberration for reception and to produce spatial phase bias for transmission concurrently in the same telescope. On this basis, the point target radar equation in a full space and time treatment is achieved. Correspondingly, the complete collection equations of 2-D data acquired in the range and azimuth directions for 2-D SAL imaging of the strip-map mode and the spotlight mode are developed. Then the imaging azimuth and range resolutions are redefined in terms of the idea of optical imaging by a lens, and the requirement for azimuth sampling is given. The paper systemically presents the all details.

A detailed laboratory experiment has been completed which models a simultaneous multiple beam Fourier telescopy (FT) technique capable of imaging rapidly changing objects. Fourier telescopy uses multiple beams that illuminate the target with a complex fringe pattern that sweeps across it due to frequency differences between beams. Using this method, the target spatial frequency components are encoded in the temporal signal that is reflected from the target. Previous work has concentrated on system designs where the target is illuminated with 3 individual beams in order to use a standard phase closure process. Data processing and image reconstruction for this laboratory experiment invoked a novel reconstruction algorithm that has been previously developed. The algorithm compensates for atmospheric phase fluctuations affecting the large number of beams transmitted simultaneously and includes a new type of global phase closure which allows image reconstruction from the time history of measured total reflected intensity from the target. The reconstruction algorithm also solves for hundreds of image Fourier components simultaneously, permitting rapid reconstruction of the image. This multiple beam laboratory experiment includes effects from realistic photon and speckle noise. Additional effects have been expanded to include uplink turbulence, piston jitter, and beam scintillation on the target, which will be encountered in an actual FT imaging system. Experimental results have obtained reconstructed image Strehl values which are greater than 0.9 under scaled system conditions.