Gaussian profile estimation in one dimension: erratum.

This erratum corrects errors in Appl. Opt.46, 5374 (2007)APOPAI0003-693510.

Effects of collection geometry variations on linear and circular polarization persistence in both isotropic-scattering and forward-scattering environments.

We present simulation and experimental results showing circular polarization is more tolerant of optical collection geometry (field of view and collection area) variations than linear polarization for forward-scattering environments. Circular polarization also persists superiorly in the forward-scattering environment compared to linear polarization by maintaining its degree of polarization better through increasing optical thicknesses. In contrast, both linear and circular polarizations are susceptible to collection geometry variations for isotropic-scattering (Rayleigh regime) environments, and linear polarization maintains a small advantage in polarization persistence.

Imaging of in vitro parenteral drug precipitation.

Solid particulate matter introduced into the bloodstream as a result of parenteral drug administration can produce serious pathological conditions. Particulate matter that cannot be eliminated by pre-infusion filtration is often the result of drug precipitation that occurs when certain parenteral formulations are mixed with blood. A new device is designed to model the mixing of drug formulations with flowing blood utilizing a uniquely designed flow cell and a CCD camera to view the formulation as it is mixed with a blood surrogate in real time.

Evolution of circular and linear polarization in scattering environments.

This work quantifies the polarization persistence and memory of circularly polarized light in forward-scattering and isotropic (Rayleigh regime) environments; and for the first time, details the evolution of both circularly and linearly polarized states through scattering environments. Circularly polarized light persists through a larger number of scattering events longer than linearly polarized light for all forward-scattering environments; but not for scattering in the Rayleigh regime. Circular polarization's increased persistence occurs for both forward and backscattered light.

New infrared transmitting material via inverse vulcanization of elemental sulfur to prepare high refractive index polymers.

Polymers for IR imaging: The preparation of high refractive index polymers (n = 1.75 to 1.86) via the inverse vulcanization of elemental sulfur is reported.

Spatial heterodyne interferometry with polarization gratings.

The implementation of a polarization-based spatial heterodyne interferometer (SHI) is described. While a conventional SHI uses a Michelson interferometer and diffraction gratings, our SHI exploits mechanically robust Wollaston prisms and polarization gratings. A theoretical model for the polarization SHI is provided and validated with data from our proof of concept experiments.

Selective polarization imager for contrast enhancements in remote scattering media.

Conventional intensity imaging through turbid media suffers from rapid loss of image contrast due to light scattering from particles or random variations of refractive index. This paper features the development of an active imaging, snapshot, system design and postprocessing algorithms that differentiate between radiation that scatters or reflects from remote, obscured objects and the radiation from the scattering media itself through a combination of polarization difference imaging, channel blurring, and Fourier spatial filtering. The produced sensor acquires and processes image data in real time, yielding improved image contrasts by factors of 10 or greater for dense water vapor obscurants.

Snapshot imaging Mueller matrix polarimeter using polarization gratings.

A snapshot imaging Mueller matrix polarimeter (SIMMP) is theoretically described and empirically demonstrated through simulation. Spatial polarization fringes are localized onto a sample by incorporating polarization gratings (PGs) into a polarization generator module. These fringes modulate the Mueller matrix (MM) components of the sample, which are subsequently isolated with PGs in an analyzer module.

White-light channeled imaging polarimeter using broadband polarization gratings.

A white-light snapshot channeled linear imaging (CLI) polarimeter is demonstrated by utilizing polarization gratings (PGs). The CLI polarimeter is capable of measuring the two-dimensional distribution of the linear Stokes polarization parameters by incorporating two identical PGs, in series, along the optical axis. In this configuration, the general optical shearing functionality of a uniaxial crystal-based Savart plate is realized.

Infrared hyperspectral imaging polarimeter using birefringent prisms.

A compact short-wavelength and middle-wavelength infrared hyperspectral imaging polarimeter (IHIP) is introduced. The sensor includes a pair of sapphire Wollaston prisms and several high-order retarders to form an imaging Fourier transform spectropolarimeter. The Wollaston prisms serve as a birefringent interferometer with reduced sensitivity to vibration versus an unequal path interferometer, such as a Michelson.

White-light Sagnac interferometer for snapshot multispectral imaging.

The theoretical and experimental demonstration of a multispectral Sagnac interferometer (MSI) is presented. The MSI was created by including two multiple-order blazed diffraction gratings in both arms of a standard polarization Sagnac interferometer (PSI). By introducing these high-order diffractive structures, unique spectral passbands can be amplitude modulated onto coincident carrier frequencies.

White light Sagnac interferometer for snapshot linear polarimetric imaging.

The theoretical and experimental demonstration of a dispersion-compensated polarization Sagnac interferometer (DCPSI) is presented. An application of the system is demonstrated by substituting the uniaxial crystal-based Savart plate (SP) in K. Oka's original snapshot polarimeter implementation with a DCPSI.

Snapshot polarimeter fundus camera.

A snapshot imaging polarimeter utilizing Savart plates is integrated into a fundus camera for retinal imaging. Acquired retinal images can be processed to reconstruct Stokes vector images, giving insight into the polarization properties of the retina. Results for images from a normal healthy retina and retinas with pathology are examined and compared.

Gaussian profile estimation in two dimensions.

We extend recent results for estimating the parameters of a one-dimensional Gaussian profile to two-dimensional profiles, deriving the exact covariance matrix of the estimated parameters. While the exact form is easy to compute, we provide a set of close approximations that allow the covariance to take on a simple analytic form. This not only provides new insight into the behavior of the estimation parameters, but also lays a foundation for clarifying previously published work.

Analysis of computed tomographic imaging spectrometers. I. Spatial and spectral resolution.

Computed tomographic imaging spectrometers measure the spectrally resolved image of an object scene in an entirely different manner from traditional whisk-broom or push-broom systems, and thus their noise behavior and data artifacts are unfamiliar. We review computed tomographic imaging spectrometry (CTIS) measurement systems and analyze their performance, with the aim of providing a vocabulary for discussing resolution in CTIS instruments, by illustrating the artifacts present in their reconstructed data and contributing a rule-of-thumb measure of their spectral resolution. We also show how the data reconstruction speed can be improved, at no cost in reconstruction quality, by ignoring redundant projections within the measured raw images.

Prismatic imaging polarimeter calibration for the infrared spectral region.

The calibration of a complete Stokes birefringent prismatic imaging polarimeter (BPIP) in the MWIR is demonstrated. The BPIP technique, originally developed by K. Oka, is implemented with a set of four Yttrium Vanadate (YVO(4)) crystal prisms.

Compact and miniature snapshot imaging polarimeter.

We present and demonstrate a compact and miniature snapshot imaging polarimeter camera; it is anticipated that such a camera can be scaled down to less than 1.5 cm. Two Savart plates are used at the pupil plane to generate multiple fringes to encode the full Stokes vector in a single image.

Fourier transform channeled spectropolarimetry in the MWIR.

A complete Fourier Transform Spectropolarimeter in the MWIR is demonstrated. The channeled spectral technique, originally developed by K. Oka, is implemented with the use of two Yttrium Vanadate (YVO(4)) crystal retarders.

Gaussian profile estimation in one dimension.

We present several new results on the classic problem of estimating Gaussian profile parameters from a set of noisy data, showing that an exact solution of the maximum likelihood equations exists for additive Gaussian-distributed noise. Using the exact solution makes it possible to obtain analytic formulas for the variances of the estimated parameters. Finally, we show that the classic formulation of the problem is actually biased, but that the bias can be eliminated by a straightforward algorithm.

Modeling and optimization for a prismatic snapshot imaging polarimeter.

Thin birefringent prisms placed near an image plane introduce sinusoidal fringes onto a 2D polarized scene making possible a snapshot imaging polarimeter, which encodes polarization information into the modulation of the fringes. This approach was introduced by Oka and Kaneko [Opt. Express 11, 1510 (2003)], who analyzed the instrument through the Mueller calculus.

Linear operator theory of channeled spectropolarimetry.

Channeled spectropolarimetry is a snapshot method of measuring the spectral and polarization content of light. Wave-number domain amplitude modulation is employed to encode all four Stokes component spectra into a single optical power spectrum. We model the channeled spectropolarimeter as a linear operator, which facilitates treatment of nonideal effects and provides a convenient framework for simulations, calibration, and reconstruction.

Recovery of a flawed hyperspectral imager calibration using optical modeling.

A reconstructed hyperspectral datacube has been successfully recovered from a badly flawed point-spread function (PSF) observation. The corrected PSF alleviated unnoticed detector saturation and misregistration artifacts in the calibration of a crucial, irreplaceable near-infrared flash hyperspectral imager dataset. This flawed PSF induced a defocus-like artifact as well as spectral distortions in the three-dimensional hyperspectral estimate of the data.

Linear calibration and reconstruction techniques for channeled spectropolarimetry.

Channeled spectropolarimetry is a novel method of measuring the spectral and polarization content of light. It employs amplitude modulation to encode all four Stokes component spectra into a single optical power spectrum. We describe a practical approach to system calibration and object reconstruction, which is able to account for important non-ideal effects.