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Infrared Radiation From Explosions in a Spark-Ignition Engine

Description: This report presents the results of an investigation to determine the variations in intensity and spectral distribution of the radiant energy emitted by the flames during normal and knocking explosions in an engine. Radiation extending into the infrared was transmitted by a window of fluorite, placed either near the spark plug or over the detonation zone at opposite ends of the combustion chamber. Concave, surface-silvered mirrors focused the beam, first at the slit of a stroboscope which opened for about 2 degrees of crank angle at any desired point in the engine cycle, and then upon the target of a sensitive thermocouple for measuring radiation intensity.
Date: February 27, 1934
Creator: Marvin, Charles F., Jr.; Caldwell, Frank R. & Steele, Sydney
Partner: UNT Libraries Government Documents Department

Application of Thermal Imagery and Aerial Photography to Hydrologic Studies of Karst Terrane in Missouri

Description: From abstract: Planning waste-disposal facilities and impoundments is complicated by karst carbonate terrane in the Ozarks. Thermal imagery (8-13 micrometer wavelength) and color infrared photography aid in identifying losing streams, sinkholes and hydrologic conditions encouraging collapse. Imagery and photography were acquired in Greene and Reynold Counties, Mo., in March 1972 and June 1973. Differences in thermal levels correlating with losing and gaining reaches of Logan Creek valley, Reynolds County, were not visually apparent in predawn March imagery but statistical analysis of predawn magnetic-tape data indicated greater variance in emitted energy from the losing reach than from the gaining reach.
Date: September 1977
Creator: Harvey, E. J.; Williams, J. H. & Dinkel, T. R.
Partner: UNT Libraries Government Documents Department

Long wavelength infrared camera (LWIRC): a 10 micron camera for the Keck Telescope

Description: The Long Wavelength Infrared Camera (LWIRC) is a facility instrument for the Keck Observatory designed to operate at the f/25 forward Cassegrain focus of the Keck I telescope. The camera operates over the wavelength band 7-13 {micro}m using ZnSe transmissive optics. A set of filters, a circular variable filter (CVF), and a mid-infrared polarizer are available, as are three plate scales: 0.05``, 0.10``, 0.21`` per pixel. The camera focal plane array and optics are cooled using liquid helium. The system has been refurbished with a 128 x 128 pixel Si:As detector array. The electronics readout system used to clock the array is compatible with both the hardware and software of the other Keck infrared instruments NIRC and LWS. A new pre-amplifier/A-D converter has been designed and constructed which decreases greatly the system susceptibility to noise.
Date: May 1, 1998
Creator: Wishnow, E.H.; Danchi, W.C.; Tuthill, P.; Wurtz, R.; Jernigan, J.G. & Arens, J.F.
Partner: UNT Libraries Government Documents Department

Optimization of Blazed Quantum Grid Infrared Photodetectors

Description: In a quantum grid infrared photodetector (QGIP), the active multiple quantum well material is patterned into a grid structure. The purposes of the grid are on the one hand to create additional lateral electron confinement and on the other to convert part of the incident light into parallel propagation. With these two unique functions, a QGIP allows intersubband transition to occur in all directions. In this work, we focused on improving the effectiveness of a QGIP in redirecting the propagation of light using a blazed structure. The optimization of the grid parameters in terms of the blaze angle and the periodicity was performed by numerical simulation using the modal transmission-line theory and verified by experiment. With a blazed structure, the sensitivity of a QGIP can be improved by a factor of 1.8 compared with a regular QGIP with rectangular profiles.
Date: July 7, 1999
Creator: Chen, C.J.; Choi, K.K.; Jiang, M.; Rokhinson, L.P.; Tamir, T.; Tsui, D.C. et al.
Partner: UNT Libraries Government Documents Department

Monsters and babies from the first/IRAS survey

Description: Radio continuum emission at cm wavelengths is relatively little affected by extinction. When combined with far-infrared (FIR) surveys this provides for a convenient and unbiased method to select (radio-loud) AGN and starbursts deeply embedded in gas and dust-rich galaxies. Such radio-selected FIR samples are useful for detailed investigations of the complex relationships between (radio) galaxy and starburst activity, and to determine whether ULIRGs are powered by hidden quasars (monsters) or young stars (babies). We present the results of a large program to obtain identifications and spectra of radio-sleected, optically faint IRAS/FSC objects using the FIRST/VLA 20 cm survey (Becker, White and Helfand 1995). These objects are all radio-'quiet' in the sense that their radio power/FIR luminosities follow the well-known radio/FIR relationship for star forming galaxies. We compare these results to a previous study by our group of a sample of radio-'loud' IRAS/FSC ULIRGs selected from the Texas 365 MHz survey (Douglas et al. 1996). Many of these objects also show evidence for dominant, A-type stellar populations, as well as high ionization lines usually associated with AGN. These radio-loud ULIRGs have properties intermediate between those of starbursts and quasars, suggesting a possibile evolutionary connection. Deep Keck spectroscopic observations of three ULIRGs from these samples are presented, including high signal-to-noise spectropolarimetry. The polarimetry observations failed to show evidence of a hidden quasar in polarized (scattered) light in the two systems in which the stellar light was dominated by A-type stars. Although observations of a larger sample would be needed to allow a general conclusion, our current data suggest that a large fraction of ULIRGs may be powered by luminous starbursts, not by hidden, luminous AGN (quasars). While we used radio-selected FIR sources to search for evidence of a causal AGN/starburst connection, we conclude our presentation with a dramatic example of an AGN/starburst ...
Date: February 16, 1999
Creator: Van Bruegel, W J M
Partner: UNT Libraries Government Documents Department


Description: Normal-coordinate calculations for the S/sub 8/ molecule were revised by use of new far-infrared spectral data and a more elaborate potential function. Representation of the observed frequencies required that the basic Urey--Bradley field be supplemented with an extra quadratic cross-term between adjacent S--S bonds. (auth)
Date: January 1, 1962
Creator: Kruse, F. H.; Scott, D. W. & McCullough, J. P.
Partner: UNT Libraries Government Documents Department

Degenerate four-wave mixing and phase conjugation in a collisional plasma

Description: Although degenerate four-wave mixing (DFWM) has many practical applications in the visible regime, no successful attempt has been made to study or demonstrate DFWM for wavelengths longer than 10..mu..m. Recently, Steel and Lam established plasma as a viable DFWM and phase conjugation (PC) medium for infrared, far-infrared, and microwaves. However, their analysis is incomplete since collisional effects were not included. Using a fluid description, our results demonstrate that when collisional absorption is small and the collisional mean-free path is shorter than the nonlinear density grating scale length, collisional heating generates a thermal force which substantially enhances the phase conjugate reflectivity. When the collisional attenuation length becomes comparable to the length of the plasma, the dominant effect is collisional absorption of the pump waves. Numerical estimates of the phase conjugate reflectivity indicate that for modest power levels, gains greater than or equal to1 are possible in the submillimeter to centimeter wavelength range. This suggests that a plasma is a viable PC medium at those long wavelengths. In addition, doubly DFWM is discussed.
Date: June 1, 1986
Creator: Federici, J.F. & Mansfield, D.K.
Partner: UNT Libraries Government Documents Department

Far infrared chemical lasers. Technical progress report No. 3, August 1, 1976--July 31, 1977. [HCN]

Description: Laser oscillation at 337 and 311 ..mu..m has been obtained from HCN molecules prepared in vibrationally excited states by the reaction between cyanogen radicals and hydrogen molecules. It has likewise been observed in HCN raised to an electronically excited state by flash photolysis. The characteristics of the pulsed output are quite different in the two cases and beginnings have been made on experiments to probe the pumping and energy transfer kinetics. The rate determining step is not the reaction rate, but rather some relaxation process that eventually channels the excitation into the upper lasing state of one quantum each of CN stretch and bend. Detailed studies of the relative intensities of pure rotational lasing in OH and OD have been made. The rotational inversions are produced by rare gas-aided, adiabatic energy conversion from vibrational to rotational excitation. The process is rapid in comparison to rotational collisional relaxation. Using transfer parameters from the ''information theoretic'' analysis (R. D. Levine) computations have been made which reproduce the results in detail, providing support for the pumping mechanism proposed, and the applicability of the theory. Preliminary work on NH (from the HN/sub 3/ photolysis) has opened up extremely interesting questions concerning the electronic states of the nascent molecules and the subsequently lasing molecules. Pure rotational laser action in at least two states (one singlet and one triplet) has been measured.
Date: August 1, 1977
Creator: Robinson, D. W.
Partner: UNT Libraries Government Documents Department


Description: During the period, March 1997 – February 2006, the Principal Investigator and his research team co-authored 47 peer-reviewed papers and presented, at least, 138 papers at conferences, meetings, and workshops that were supported either in whole or in part by this agreement. We developed a state-of-the-art satellite cloud processing system that generates cloud properties over the Atmospheric Radiation (ARM) surface sites and surrounding domains in near-real time and outputs the results on the world wide web in image and digital formats. When the products are quality controlled, they are sent to the ARM archive for further dissemination. These products and raw satellite images can be accessed at http://cloudsgate2.larc.nasa.gov/cgi-bin/site/showdoc?docid=4&cmd=field-experiment-homepage&exp=ARM and are used by many in the ARM science community. The algorithms used in this system to generate cloud properties were validated and improved by the research conducted under this agreement. The team supported, at least, 11 ARM-related or supported field experiments by providing near-real time satellite imagery, cloud products, model results, and interactive analyses for mission planning, execution, and post-experiment scientific analyses. Comparisons of cloud properties derived from satellite, aircraft, and surface measurements were used to evaluate uncertainties in the cloud properties. Multiple-angle satellite retrievals were used to determine the influence of cloud structural and microphysical properties on the exiting radiation field.
Date: June 28, 2013
Creator: Minnis, Patrick
Partner: UNT Libraries Government Documents Department

Characterizing the emissivity of materials under dynamic compression (final report for LDRD project 79877).

Description: Temperature measurements are crucial to equation of state development, but difficult to perform reliably. In the case of infrared pyrometry, a large uncertainty comes from the fact that sample emissivity (the deviation from a blackbody) is unknown. In this project, a method for characterizing the emissivity of shocked materials was developed. By coupling infrared radiation from the National Synchrotron Light Source to a gas gun system, broad spectrum emissivity changes were studied to a peak stress of 8 GPa. Emissivity measurements were performed on standard metals (Al, Cr, Cu, and Pt) as well as a high emissivity coating developed at Sandia.
Date: October 1, 2007
Creator: Dolan, Daniel H.
Partner: UNT Libraries Government Documents Department

Germanium blocked impurity band far infrared detectors

Description: The infrared portion of the electromagnetic spectrum has been of interest to scientist since the eighteenth century when Sir William Herschel discovered the infrared as he measured temperatures in the sun's spectrum and found that there was energy beyond the red. In the late nineteenth century, Thomas Edison established himself as the first infrared astronomer to look beyond the solar system when he observed the star Arcturus in the infrared. Significant advances in infrared technology and physics, long since Edison's time, have resulted in many scientific developments, such as the Infrared Astronomy Satellite (IRAS) which was launched in 1983, semiconductor infrared detectors for materials characterization, military equipment such as night-vision goggles and infrared surveillance equipment. It is now planned that cooled semiconductor infrared detectors will play a major role in the ''Star Wars'' nuclear defense scheme proposed by the Reagan administration.
Date: April 1, 1988
Creator: Rossington, C.S.
Partner: UNT Libraries Government Documents Department

Filters and wavefront dividing beamsplitters for the near and mid infrared produced by micromachining techniques

Description: Band pass filters for the far infrared have been produced by etching crosses into metal films on Mylar substrates. Unsupported thin cross shaped filters for the far infrared have been produced by etching crosses into 4 microns thick nickel foils. These authors studied the dependence of the wavelength of peak transmission, bandwidth, and percentage of peak transmission on the shape of the crosses. Very accurately shaped crosses in thick metals for the mid infrared have been produced using LIGA. These filters showed a strong side peak and transmission in the 70% to 80% range. Theoretical calculations by Compton et al for thin filters predict such a side peak, depending on the shape of the cross, and 100% transmission. To obtain maximum transmission for band pass filters, a tripod shape was used instead of the cross. These filters showed 100% transmission and the side peak for a thickness of 10.5 microns. The side peak is getting smaller for thinner filters.
Date: December 31, 1993
Creator: Warren, J.; Heaney, J.B. & Moeller, K.D.
Partner: UNT Libraries Government Documents Department

Measurement of Downhole Steam Quality and Total Energy by Optical Methods

Description: Initial steps have been taken to measure the mass of water in vapor and liquid phases downhole in a steam injection heavy oil recovery system. A suitable portion of the electromagnetic spectrum has been identified over which the presence of liquid water and vapor can be separated. This is in the near infrared and extends from ~900 nm to 1.8 µm region. A high pressure and high temperature cell has been constructed and tested for stagnant transmissions. Pitting of the optical ports due to the presence of high-pressure (8.5 MPA) and high temperature (300C) water has lead to a redesign of the optical ports, these modifications will be incorporated in the next quarter. The actual determination of the mass of water, either in liquid or vapor, has not been reliably determined, due in part to the pitting problems being addressed in the modification. However, qualitative data has been recorded clearly showing an increase in absorption with increasing number of absorbing molecules, i.e. mass of water.
Date: April 1, 1998
Creator: Donaldson, A. B. & Allen, Graham R.
Partner: UNT Libraries Government Documents Department

Vertical Cavity Surface Emitting Lasers

Description: The goal of this project was to increase the power of vertical cavity surface emitting lasers and to convert their wavelength into the blue/ultraviolet and the infrared for sensing applications. We have increased the power to the multi-watt level and have generated several milliwatts of blue light using optical pumping. Electrical pump has been less successful, but we have identified the problems and begun work to overcome them using a bottom emitting design.
Date: November 1, 2002
Partner: UNT Libraries Government Documents Department

Interband cascade light emitting devices based on type-II quantum wells

Description: The authors discuss physical processes in the newly developed type-II interband cascade light emitting devices, and review their recent progress in the demonstration of the first type-II interband cascade lasers and the observation of interband cascade electroluminescence up to room temperature in a broad mid-infrared wavelength region (extended to 9 {mu}m).
Date: June 1, 1997
Creator: Yang, Rui Q.; Lin, C.H. & Murry, S.J.
Partner: UNT Libraries Government Documents Department

Design Study of a Visible/Infrared Periscope for Intense Radiation Applications using Reflective Optics

Description: In magnetically confined fusion devices employing deuterium-tritium (D-T) operation, refractive optical components exposed to neutron and gamma radiation can be subject to degradation of the transmission characteristics, induced luminescence, and altered mechanical properties including dimensional changes. Although radiation resistant refractive optics functioned well for the Tokamak Fusion Test Reactor (TFTR) periscope system during D-T operation, this design approach is unpromising in the much more hostile radiation environment of future D-T devices such as the International Thermonumclear Experimental Reactor (ITER). Under contract to the Princeton Plasma Physics Laboratory, Ball Aerospace of Colorado carried out a periscope design study based on the use of reflective optics. In this design, beryllium reflective input optics supported by a fused silica optical bench were interfaced to a Cassegrain relay system to transfer plasma images to remotely located cameras. This system is also capable of measuring first-wall surface temperatures in the range of 300 - 2,000 degrees C even under projected heating of the reflective optics themselves to several hundred degrees Celsius. Tests of beryllium mirror samples, however, revealed that operation at temperatures above 700 degrees C leads to a loss of specular reflectivity, thus placing an upper limit on the acceptable thermal environment. The main results of this periscope study are presented in this paper.
Date: May 1, 1998
Creator: Medley, S.S.
Partner: UNT Libraries Government Documents Department

Diffuse reflectance FTIR of stains on grit blasted metals

Description: Diffuse reflectance mid-infrared Fourier transform (DRIFT) spectroscopy has been applied to the detection of oil contamination on grit-blasted metals. The object of this application is to detect and discriminate between silicone and hydrocarbon oil contamination at levels approaching 10 mg/m{sup 2}. A portable FTIR spectrometer with dedicated diffuse reflectance optics was developed for this purpose. Using translation devices positioned by instructions from the spectrometer operating system, images of macroscopic substrates were produced with millimeter spatial resolution. The pixels that comprise an image are each a full mid-infrared spectrum with excellent signal-to-noise, each determined as individual files and uniquely saved to disc. Reduced spectra amplitudes, based on peak height, area, or other chemometric techniques, mapped as a function of the spatial coordinates of the pixel are used to display the image. This paper demonstrates the application of the technique to the analysis of stains on grit-blasted metals, including the calibration of the method, the inspection of substrates, and the migration of oil contamination.
Date: August 9, 1997
Creator: Powell, G.L.; Hallman, R.L. Jr. & Cox, R.L.
Partner: UNT Libraries Government Documents Department