Abstract-A two-layer dual-waveguide probe measurement geometry is proposed to nondestructively measure the complex permittivity and permeability of planar materials. The new measurement structure consists of two rectangular waveguides attached to a PEC flange plate that is placed against the material under test, followed by a known material layer backed by a PEC. The purpose for this new measurement geometry is to improve the permittivity results obtained using the existing dual-waveguide probe geometries, namely, the PEC-backed and free-space-backed geometries, by permitting a larger electric field into the material under test and increasing the field coupling between the two rectangular waveguide apertures. The theoretical development of the technique is presented extending the existing single-layer PEC-backed method to the proposed two-layer dual-waveguide probe method. The new measurement structure is theoretically analyzed by replacing the waveguide apertures with equivalent magnetic currents as stipulated by Love's equivalence theorem.Making use of the magnetic-current-excited two-layer parallel-plate Green's function and enforcing the continuity of the transverse magnetic fields over the waveguide apertures results in a system of coupled magnetic field integral equations. These coupled magnetic field integral equations are then solved for the theoretical reflection and transmission coefficients using the Method of Moments. The desired complex permittivity and permeability of the material under test are found by minimizing the root-mean-square difference between the theoretical and measured reflection and transmission coefficients, i.e., numerical inversion. Last, experimental results utilizing the new two-layer technique are presented for two magnetic 124Seal, Hyde, and Havrilla shielding materials and subsequently compared to the existing PECbacked and free-space-backed dual-waveguide probe geometries.

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Abstract. Calibration of CCD arrays for identifying bad pixels and achieving nonuniformity correction is commonly accomplished using dark frames. This kind of calibration technique does not achieve radiometric calibration of the array since only the relative response of the detectors is computed. For this, a second calibration is sometimes utilized by looking at sources with known radiances. This process can be used to calibrate photodetectors as long as a calibration source is available and is well-characterized. A previous attempt at creating a procedure for calibrating a photodetector using the underlying Poisson nature of the photodetection required calculations of the skewness of the photodetector measurements. Reliance on the third moment of measurement meant that thousands of samples would be required in some cases to compute that moment. A photocalibration procedure is defined that requires only first and second moments of the measurements. The technique is applied to image data containing a known light source so that the accuracy of the technique can be surmised. It is shown that the algorithm can achieve accuracy of nearly 2.7% of the predicted number of photons using only 100 frames of image data. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

Computing the permittivity and permeability of complex materials has previously relied on a series of simplifying assumptions to enable analysis. The most restricting requirement is that the optical axes of the material must align with the laboratory frame of reference. This requirement cannot be met for a large group of materials, including crystalline structures and metamaterials such as tilted nanorods. Currently, designing the optical characteristics of these structures would require ellipsometric analysis, which uses an error-correction-based technique. Here, a new technique built upon the underlying physics of ellipsometry is proposed to extract arbitrary permittivity and permeability tensors using a set of off-axis measurements. This new permittivity and permeability tensor extraction technique allows all 18 elements of the permittivity and permeability tensors to be nonzero and extracts them, given a set of reflectance and transmittance measurements. Several materials are analyzed here, including a) an isotopic plane of known permittivity, b) an anisotropic aligned structure, and c) a tilted-nanorod-based sample that cannot be measured using traditional methodologies. The isotropic plane shows very low error ðG 10 À4 %Þ in the x and y tensor measurements and around 1% error in the z tensor measurement at higher (metallic) permittivities. The aligned structure's characteristics are compared to measurements made with traditional techniques and show excellent agreement between the techniques. The tilted nanorod characteristics are analyzed and used to predict the reflection and transmission coefficients at other angles. The predictions compare very well with the computational electromagnetic simulations, showing at most 5% error over the range examined.