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We examine coding strategies for coded aperture scatter imagers. Scatter imaging enables tomography of compact regions from snapshot measurements. We present coded aperture designs for pencil and fan beam geometries, and compare their singular value spectra with that of the Radon transform and selected volume tomography. We show that under dose constraints scatter imaging improves conditioning over alternative techniques, and that specially designed coded apertures enable snapshot 1D and 2D tomography.

Recent developments in multiscale imaging systems have opened up the possibility for commercially viable wide-field gigapixel cameras. While multiscale design principles allow tremendous simplification of the optical design, they place increased emphasis on optomechanics and system level integration of the camera as a whole. In this paper we present the optomechanical design of a prototype two-gigapixel system (AWARE-2) that has been constructed and tested.

Monocentric multi-scale (MMS) lenses are a new approach to high-resolution wide-angle imaging, where a monocentric objective lens is shared by an array of identical rotationally symmetric secondary imagers that each acquire one overlapping segment of a mosaic. This allows gigapixel images to be computationally integrated from conventional image sensors and relatively simple optics. Here we describe the MMS design space, introducing constraints on image continuity and uniformity, and show how paraxial system analysis can provide both volume scaling and a systematic design methodology for MMS imagers. We provide the detailed design of a 120° field of viewimager (currently under construction) resolving 2 gigapixels at 41.5 μrad instantaneous field of view, and demonstrate reasonable agreement with the first-order scaling calculation.

We consider the capabilities and limits of strategies for single-aperture three-dimensional and extended depth of field optical imaging. We show that reduced spatial resolution is implicit in forward models for light field sampling and that reduced modulation transfer efficiency is intrinsic to pupil coding. We propose a novel strategy based on image space modulation and show that this strategy can be sensitive to high-resolution spatial features across an extended focal volume.

We describe an improved implementation of our previously reported common-path, phase shifting, and shearing interferometer. Using a time-multiplexed phase shifting scheme, we demonstrate higher sampling resolution, better light sensitivity, and use of arbitrary phase shifting algorithms. We describe microscopic imaging of the surface profile of a copper-plated silicon wafer and demonstrate that the system is vibration insensitive with approximately lambda/100 repeatability. In a more general discussion of our method, we describe the different functional elements and suggest alternative designs and improvements. Possible uses include full-field coherent imaging and high dynamic range wavefront sensing, which we briefly discuss.

We show that x-ray computer tomography algorithms can be applied with minimal alteration to the three-dimensional reconstruction of visible sources. Diffraction and opacity affect visible systems more severely than x-ray systems. For camera-based tomography, diffraction can be neglected for objects within the depth of field. We show that, for convex objects, opacity has the effect of windowing the angular observation range and thus blurring the reconstruction. For concave objects, opacity leads to nonlinearity in the transformation from object to reconstruction and may cause multiple objects to map to the same reconstruction. In x-ray tomography, the contribution of an object point to a line integral is independent of the orientation of the line. In optical tomography, however, a Lambertian assumption may be more realistic. We derive an expression for the blur function (the patch response) for a Lambertian source. We present experimental results showing cone-beam reconstruction of an incoherently illuminated opaque object.

We show that three-dimensional incoherent primary sources can be reconstructed from finite-aperture Fresnel-zone mutual intensity measurements by means of coordinate and Fourier transformation. The spatial bandpass and impulse response for three-dimensional imaging that result from use of this approach are derived. The transverse and longitudinal resolutions are evaluated as functions of aperture size and source distance. The longitudinal resolution of three-dimensional coherence imaging falls inversely with the square of the source distance in both the Fresnel and Fraunhofer zones. We experimentally measure the three-dimensional point-spread function by using a rotational shear interferometer.

Practical clinical optical coherence tomography (OCT) systems require automatic tools for identifying and correcting flaws in OCT images. One type of flaw is the loss of image detail owing to the dispersion of the medium, which in most cases is unknown. We present an autofocus algorithm for estimating the delay line and material dispersion from OCT reflectance data, integrating a previously presented dispersion compensation algorithm to correct the data. The algorithm is based on minimizing the Renyi entropy of the corrected axial-scan image, which is a contrast-enhancement criterion. This autofocus algorithm can be used in conjunction with a high-speed, digital-signal-processor-based OCT acquisition system for rapid image correction.

We demonstrate the sensing and correction of an isoplanatic refractive distortion (not lens aberrations), using the complete measurement of the partially coherent field in an aperture that the previously described astigmatic coherence sensor provides. Isoplanatic distortions, and in general distortions that do not cause energy loss, maintain the orthogonality of the coherent modes. We use the fact that a common distortion will occur to all coherent modes to separate the distortion from the source behind it, rather than requiring a reference source at a different wavelength. Digital deconvolution was performed on the full four-dimensional partially coherent field for simultaneously computing the distortion and the source intensity distribution.

System requirements for many military electro-optic and IR camera systems reflect the need for both wide-field-of-view situational awareness as well as high-resolution imaging for target identification. In this work we present a new imaging system architecture designed to perform both functions simultaneously and the AWARE 10 camera as an example at visible wavelengths. We first describe the basic system architecture and user interface followed by a laboratory characterization of the system optical performance. We then describe a field experiment in which the camera was used to identify several maritime targets at varying range. The experimental results indicate that users of the system are able to correctly identify ~10 m targets at between 4 and 6 km with 70% accuracy.

We present a wide-field compact f-1.2, f-1.6 effective illumination catadioptric telescope that spans the wavelengths 0.7-14.0 μm. Such a telescope replaces several telescopes designed for different infrared bands, while having a track length shorter than most single-band telescopes. Incorporated with a suitable multiband focal plane array, many wavelength bands may be imaged simultaneously in the same instrument. We have constructed and tested prototypes of the telescopes and found the performance is near the predicted values.

Compressive holography applies sparsity priors to data acquired by digital holography to infer a small number of object features or basis vectors from a slightly larger number of discrete measurements. Compressive holography may be applied to reconstruct three-dimensional (3D) images from two-dimensional (2D) measurements or to reconstruct 2D images from sparse apertures. This paper is a tutorial covering practical compressive holography procedures, including field propagation, reference filtering, and inverse problems in compressive holography. We present as examples 3D tomography from a 2D hologram, 2D image reconstruction from a sparse aperture, and diffuse object estimation from diverse speckle realizations.

Multiscale cameras achieve wide-angle, high-resolution imaging by combining coarse image formation by a simplified wide-field objective with localized aberration correction in an array of narrow field microcameras. Microcamera aperture size is a critical parameter in multiscale design; a larger aperture has greater capacity to correct aberration but requires a more complex microcamera optic. A smaller aperture requires integration of more microcameras to cover the field. This paper analyzes multiscale system performance as a function of microcamera aperture for 2 and 40 gigapixel monocentric objective lenses. We find that microcamera aperture diameters of 3 to 12 mm paired with complementary metal oxide semiconductor sensors in the 1 to 15 megapixel range are most attractive for gigapixel-scale cameras.

Off-axis digital holography typically uses a beam splitter to combine reference and object waves at an angle matched to the sampling period of the sensor array. The beam splitter determines the thickness of the recording system. This paper describes and demonstrates a total internal reflection hologram that replaces the beam splitter and enables hologram recording over a large aperture with a thin camera.

We propose an estimation-theoretic approach to the inference of an incoherent 3D scattering density from 2D scattered speckle field measurements. The object density is derived from the covariance of the speckle field. The inference is performed by a constrained optimization technique inspired by compressive sensing theory. Experimental results demonstrate and verify the performance of our estimates.

We demonstrate in vivo optical coherence tomography using a Fourier-domain optical delay line constructed with a commercially available polygonal scanner. The 20-faceted polygonal mirror array, capable of scanning at rates up to 15 kHz, is implemented at 4 kHz to acquire 500 500 pixel images at 8 framess with a signal-to-noise ratio of 80 dB. Features of this delay line include scalability to high repetition rates, 98.6% linearity in group delay over 2 mm, and bandwidth support exceeding 150 nm. Images are obtained in an animal model Xenopus laevis, and limitations due to phase-delay nonlinearity and polygon asymmetry are discussed. © 2003 Optical Society of America OCIS codes: 110.4500, 120.3180, 120.5800, 170.4500.

The resolution of optical coherence tomography (OCT) often suffers from blurring caused by material dispersion. We present a numerical algorithm for computationally correcting the effect of material dispersion on OCT reflectance data for homogeneous and stratified media. This is experimentally demonstrated by correcting the image of a polydimethyl siloxane microfludic structure and of glass slides. The algorithm can be implemented using the fast Fourier transform. With broad spectral bandwidths and highly dispersive media or thick objects, dispersion correction becomes increasingly important.