Narrow Results

The Defence Research and Development Canada Agency has successfully completed a Technology Demonstration Program to assess the military utility of airborne hyperspectral Imagery. This required developing a sensor, the Airborne Infrared Imaging Spectrometer (AIRIS), and collecting in-flight imagery data. AIRIS was designed as a flexible instrument using a Fourier Transform spectrometer with a spectral resolution ranging from 1 to 16 cm⁻¹, wide spectral coverage (2 to 12 microns), and different optical configurations. This paper provides a description of AIRIS and discusses examples of the spectral images collected during one air-trial. Emphasis is put on images of sub-pixel targets. Processing AIRIS data is labor intensive and can only be performed during post-trial analysis. Hardware and software modifications to AIRIS will implement a real-time processing capability over the next three years. These modifications will enable the instrument to output radiometrically calibrated digital spectrograms. These spectrograms will then be processed in real-time to output target detection and identification for selected target types.

This paper presents comparative analysis of different wavelength ranges for the spectroscopic detection of acetone vapor. We collected and analyzed original absorption line spectra arising from electronic transitions in the ultraviolet, near-infrared vibrational overtones, mid-infrared fundamentals, THz torsional modes, and mm-wave rotational transitions. Peak absorption cross sections of prominent spectral features are determined. The relative merit of each spectral range for sensing is considered, taking into account the absorption strength, available technology, and possible interferences.

Heavy loads of aerosols in the air have considerable health effects in individuals who suffer from chronic breathing difficulties. This problem is more acute in the Middle-East, where dust storms in winter and spring transverse from the neighboring deserts into dense populated areas. Discrimination between the dust types and association with their source can assist in assessment of the expected health effects. A method is introduced to characterize the properties of dense dust clouds with passive IR spectral measurements. First, we introduce a model based on the solution of the appropriate radiative transfer equations. Model predictions are presented and discussed. Actual field measurements of silicone-oil aerosol clouds with an IR spectro-radiometer are analyzed and compared with the theoretical model predictions. Silicone-oil aerosol clouds have been used instead of dust in our research, since they are composed of one compound in the form of spherical droplets and their release is easily controlled and repetitive. Both the theoretical model and the experimental results clearly show that discrimination between different dust types using IR spectral measurements is feasible. The dependence of this technique on measurement conditions, its limitations, and the future work needed for its practical application of this technique is discussed.

Optical MEMS technology combined with broadband infrared sensor technology is used to realize wavelength-tunable infrared sensors. This paper describes the ongoing research into one such sensor design based on an electrically tunable Fabry-Pérot cavity. Theory, measured results and future research directions are presented and discussed for the single-sensor design currently being developed, in the context of the intended application of this technology; the development of lightweight, portable and robust multi-spectral imaging systems.

The background photon shot noise, induced by the signal itself and all other in-band surroundings, provides the fundamental infrared imaging sensitivity limit (background limited performance or BLIP). Optical diffraction constrains resolution angle to values greater than the ratio of the detection wavelength to the optics diameter. Imaging technology tries to attain BLIP at spatial frequencies approaching the diffraction limit while minimizing system size, weight, power, and life-cycle cost.

To minimize costs, detector array technology must raise the detector operating temperature while keeping dark currents and other noise mechanisms below background shot noise. This requires reducing material and process defects. Recently HgCdTe has seen the MWIR-LWIR device dark currents to be limited only by fundamental mechanisms over a wide range of temperatures and wavelengths. Novel materials systems (e.g. Type-II superlattices) in theory have even lower fundamental limits than HgCdTe, but as yet lag in demonstrated performance. At least for now HgCdTe provides a convenient well-characterized benchmark and gives insight into further improvement possibilities

Infrared imaging technology must also exploit advanced processing and packaging techniques to reduce detector pitch to a few wavelengths of detected light. Mid- and long-wave infrared imaging arrays with ~15μm detector dimensions are now approaching this goal.

GaInSb and AlGaInSb compositionally graded buffer layers grown on GaSb by MBE were used to develop unrelaxed InAs_1-xSb_x epitaxial alloys with strain-free native lattice constants up to 2.1% larger than that of GaSb. The in-plane lattice constant of the strained top buffer layer was grown to be equal to the native, unstrained lattice constant of InAs_1-xSb_x with given x. The InAs_0.56Sb_0.44 layers demonstrated a photoluminescence (PL) peak at 9.4 μm at T = 150 K. The minority carrier lifetime measured at 77 K for InAs_0.8Sb_0.2 was 250 ns.

The joint U.S. and German SOFIA project to develop and operate a 2.5-meter infrared airborne telescope in a Boeing 747-SP is now in its final stages of development. Flying in the stratosphere, SOFIA allows observations through the infrared and submillimeter region, with an average transmission of ≳ 80%. SOFIA is characterized by a wide instrument complement ranging from broadband imagers, through moderate resolution spectrographs capable of resolving broad features due to dust and large molecules, to high resolution spectrometers suitable for kinematic studies of molecular and atomic gas lines at km/s resolution. This broad range in instruments will enable SOFIA to make unique contributions to a broad array of science topics. First science flights will begin in 2009 and the observatory is expected to operate for over 20 years. The sensitivity, characteristics, science instrument complement, and examples of first light science are discussed.

Implicit Regularization is a four-dimensional regularization initially conceived to treat ultraviolet divergences. It has been successfully tested in several instances in the literature, more specifically in those where Dimensional Regularization does not apply. In the present contribution, we extend the method to handle infrared divergences as well. We show that the essential steps which rendered Implicit Regularization adequate in the case of ultraviolet divergences have their counterpart for infrared ones. Moreover, we show that a new scale appears, typically an infrared scale which is completely independent of the ultraviolet one. Examples are given.

Optical conductivity spectra of conducting oxides including high-T_C cuprates - compared to non-superconducting nickelates in particular - deduced from infrared reflectivity spectroscopy in polarized light and their doping and temperature dependence, are discussed with emphasis on the signatures of intrinsic inhomogeneities of charge carrier concentration. The model of disordered metal is shown to be compatible with the general loss of spectral weight in the optical conductivity upon decreasing frequency, instead of a maximum conductivity at zero frequency as found within a Drude description. In high-T_C multilayer cuprates, the discussion focuses upon the c-axis response and the inhomogeneity of the electronic concentration related to the conducting planes alternating with insulating sheets. The onset of stripes that are intrinsic inhomogeneities of the charge carrier distribution is discussed in the example of nickelates.

Pure and antimony doped barium titanate powders were prepared by polymeric precursors method through Pechini process, which was carried out as a three-stage process from organometallic complex. Obtained powder was pressed into pellets and sintering was performed at 1300 °C for 8 h with heating rate of 10 °C min-1. The formation of phase and crystal structure of pure and Sb-doped barium titanate was approved by XRD analysis, Raman and IR spectroscopy. The influence of Sb doping on microstructure of barium titanate ceramics was investigated by scanning electron microscopy. Therefore, the relation between grain size, structure and properties of the obtained ceramics was analyzed. Influence of Sb doping on barium titanate properties was discussed.

X-ray diffraction (XRD) method and structural refinement were used to characterize the sample of $\alpha$-Si₃N₄. Rietveld analyses of XRD data confirmed that the sample belongs to hexagonal crystal (space group of P31c, No:159). The refined structural parameters are in agreement with the available theoretical and synchrotron radiation experimental results. Then, the infrared (IR) spectra of $\alpha$-Si₃N₄ under 22 GPa were investigated with the diamond anvil cell (DAC). According to the IR absorption spectra at 296.3 K and 2 hPa (Observation range from 400 cm${}^{-1}$ to 12,500 cm${}^{-1}$), we observed 23 IR active peaks. Normalized Fourier transform infrared (FTIR) absorption spectra under high pressure and room-temperature (296.3 K) show that $\alpha$-Si₃N₄ undergoes a phase transition at 16.3 GPa and changes from hexagonal to cubic phase, namely, $\gamma$-Si₃N₄, which is very close to the result of our theoretical calculations, i.e., the phase transition pressure is 16.3 GPa.

This paper presents the design of C-CNTFET oscillator's arrays for infrared 'IR' technology. These arrays are contained by both of the LC-tank and the voltage control 'coupled N- and P-type C-CNTFET LC-tank' oscillators. In this paper, the analysis of the impact of CNT diameter variations and the nonlinear capacitances (C_GD and C_GS) were introduced, especially on propagation time, oscillation frequency and power consumption. The C-CNTFET inverter, ring oscillator, LC-tank and coupled N- and P-type C-CNTFET LC-tank oscillator structures were designed and their speeding and performances have been investigated with the proposed n-type of C-CNTFET model supplied by a 0.5 V power voltage. Simulation results show that the n- and p-types LC-tank oscillator circuit designs achieved an approximately equal oscillation frequency, response time and power consumption. Whereas the coupled N- and P-type C-CNTFET LC-tank oscillator has the lowest power consumption equal to 0.13 μW, the highest oscillation frequency (10.08 THz) and the fastest response time (1.81 ps).

GRS 1758-258 is one of the two brightest persistent hard X–ray sources in the Galactic Center region, of which an optical/near infrared counterpart has not been unambiguously identified in previous work, mainly due to high absorption and the lack of suitable astrometric stars in early times. In this work, we take advantage of modern star catalogs to reanalyze archival images of the field in the optical and near infrared wavelengths, and compute a new astrometric solution. As a result, a single source is consistent with radio and X–ray sub-arcsec positions, which we propose as the counterpart of GRS 1758-258.

We used a multifractal approach to characterize scale by scale, the remotely sensed visible and thermal-infrared volcanic field, at Kilauea Volcano, Hawaii, USA. Our results show that (1) the observed fields exhibit a scaling behavior over a resolution range of ~ 2.5 m to 6 km, (2) they show a strong multifractality, (3) the multifractal parameters α, C₁ and H are sensitive to volcanic structural classes such as vent cones, lava ponds and active to inactive lava flows, (4) vegetation area and volcanic gas plumes have a strong effect on the multifractal estimates, and (5) vegetation and cloud-free images show statistical characteristics due to topography related albedo in the visible and predominantly solar heating in the thermal infrared wavelengths.

A spectrophotometric study of 1:1 donor–acceptor complex, cobalt (III) acetylacetonate (donor) and iodine (σ-acceptor) has been preformed. The equilibrium constants, (K) and the absorpitivity (ε) for the formation of the iodine complex have been calculated. The predicted structure of the solid triiodide charge-transfer complex reported in this study is further supported by thermal, far and mid infrared spectroscopic measurements. Electron transfer from Co (acac = 2, 4-pentanedionate)₃ to iodine leads to the formation of an organic semiconductor with the formula of . The kinetic parameters (nonisothermal method) for their decomposition have been evaluated by graphical methods using the equations of Freeman–Carroll (FC), Horowitz–Metzger (HM) and Coats–Redfern (CR). The ac conductivity and dielectric properties of have been measured over the frequency 50–10⁶ Hz at temperature 298 K.

Nonlinear processes in quantum well infrared photodetectors (QWIP) are reviewed. Being an intersubband dipole transition based photoconductor, the nonlinear behaviors in QWIPs are caused by both the (extrinsic) photoconductive transport mechanism and (intrinsic) nonlinear optical processes. Extrinsic nonlinearity leads to a degradation of QWIP performance at high incident power or low operating temperatures. Some intrinsic nonlinear QWIP properties are useful in applications, such as in autocorrelation of short pulses by two-photon absorption. The general area of QWIP nonlinear properties has not been extensively investigated. We point out some directions for further studies and hope to stimulate more research activities.

The Raman (3500cm${}^{-1}-$100cm${}^{-1})$ and IR spectra (4000cm${}^{-1}-$400cm${}^{-1})$ of liquid trimethylacetonitrile (C₅H₉N, TMA) have been obtained. In addition, the ¹H and ${}^{13}$C NMR spectra of TMA were obtained in DMSO-${\mathrm{\text{d}}}_6$ and CDCl₃. The staggered conformer (C${}_{\mathrm{\text{3v}}})$ was favored using MP2 and DFT(B3LYP/$\omega$B97XD) quantum mechanical calculations utilizing a 6-311$+$G(d,p) basis set. High energy difference estimates of 4534cm${}^{-1}-$5338cm${}^{-1}$ (12.96kcal/mol$-$15.26kcal/mol) were predicted, along with three imaginary torsion frequencies for the eclipsed conformer, therefore considered a transition state. The ¹H and ${}^{13}$C NMR chemical shifts were predicted with B3LYP and $\omega$B97XD methods using the GIAO approximation and 6-311$+$G(d,p) basis set. B3LYP frequencies calculation is favored herein owing to the relatively good compilation with the experimental measurements. The computed structural parameters are well correlated to those reported from electron diffraction and microwave studies. Moreover, the ${}^{13}$C${-}^1$H coupling constant was estimated and found consistent with that observed for the sample dissolved in DMSO-${\mathrm{\text{d}}}_6$/CDCl₃ solvents. Using the observed methyl torsion at 266cm${}^{-1}$ in gas phase and the kinetic parameter F number, a potential function (V${}_3)$ of $1578\pm 30$cm${}^{-1}$($4.51\pm .09$kcal/mol) was obtained, this barrier to internal rotation is well correlated to 1527cm${}^{-1}$ (4.37kcal/mol) predicted from MP2/6-311$+$G(d,p) potential surface scan. Aided by the predicted wavenumbers and their IR intensity/Raman activity, the observed IR/Raman bands were intensively discussed and therefore assigned to their corresponding fundamentals, in agreement with novel normal coordinate analysis and potential energy distributions (PEDs).

An innovative NDT (non-destructive testing) technique for interrogating materials for their defects has been developed successfully. The technique has a novel approach to data analysis by employing intensity, RGB signal re-mix and wavelength variation of a thermally generated IR-beam onto the specimen under test which can be sensed and displayed on a computer screen as an image. Specimen inspection and data analysis are carried out through pixel level re-ordering and shelving techniques within a transformed image file using a sequence grouping and regrouping software system, which is specifically developed for this work. The interaction between an impact damaged RIM composite structure and thermal energy is recorded, analyzed, and modeled using an equivalent Electronic circuit. Effect of impact damage on the integrity of the composite structure is also discussed.

This paper presents a new preparation scheme of monolithic pyroelectric thin film infrared sensor. The sensor can be prepared directly on readout circuit and its electrode can be connected to the readout circuit through a via. PbTiO₃ thin film is used as pyroelectric material. Porous SiO₂ thin film is applied onto silicon wafer to improve the thermal isolation of the pyroelectric layer. Copper interconnection is used in readout circuit to solve the problem that aluminium interconnection can't endure the annealing temperature of PbTiO₃ thin film.

Two-dimensional thermal analysis of multi-layer thin film pyroelectric infrared detectors is performed according to the structure and test conditions of detectors and the temperature distribution of detectors is obtained. Result shows that the insulation layer of multi-layer film pyroelectric infrared detector can effectively reduce thermal flow from pyroelectric layer substrate and the response of detector increases with the increasing of insulation layer thickness; when the thermal conductivity of insulation layer is lower than of air, its performance is better than micro-bridge structure.