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- Adaptive optics (2)
- Adaptive control systems (1)
- Adaptive template (1)
- Anions (1)
- Atmospheric motion (1)
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- Atmospheric optics (1)
- Automatic tracking (1)
- Bromine (1)
- Cathodoluminescence (1)
- Cations (1)
- Control theory (1)
- Correlation (1)
- Correlation (Statistics) (1)
- Electron impact ionization (1)
- Energy transfer (1)
- Fourier transform spectroscopy (1)
- Glow discharges--Computer simulation (1)
- Holography (1)
- Image processing (1)
- Interferometers (1)
- Lasers--Measurement (1)
- Nonlinear optics (1)
- Optical correlators (1)
- Optical detectors (1)
- Optical switching (1)
- Phase detectors (1)
- Photo bleaching (1)
- Polythiophene (1)
- Semiconductor lasers (1)
- TEOS (1)
Articles 1 - 14 of 14
Full-Text Articles in Physics
Collisional Detachment Of Anions Using Fourier Transform Mass Spectrometry, Kevin B. Riehl
Collisional Detachment Of Anions Using Fourier Transform Mass Spectrometry, Kevin B. Riehl
Theses and Dissertations
Fourier Transform Mass Spectrometry (FTMS) is used to make energy resolved ion-neutral reaction measurements at high translational energies (up to several hundred eV). The technique is demonstrated for collisional detachment of anions, and should be easily applied to other inelastic reactions. Collisional detachment cross sections of iodine anions onto gas phase targets of neon, xenon, and trifluoromethyl iodide are measured for 1-300 eV (lab frame). Peak detachment cross sections are roughly 2, 8.5, and 7 Å2, respectively. Ion kinetic measurements show the iodine anion is unreactive in trifluoromethyl iodide at thermal energies. Positive ion chemistry is consistent with …
Remote Sensing Of Turbulence And Transverse Atmospheric Wind Profiles Using Optical Reference Sources, Steven C. Koeffler
Remote Sensing Of Turbulence And Transverse Atmospheric Wind Profiles Using Optical Reference Sources, Steven C. Koeffler
Theses and Dissertations
This thesis examines a remote sensing technique for measuring the atmospheric structure constant and the transverse atmospheric wind velocity as a function of altitude by performing temporal and spatial correlations of band pass filtered wave front slope sensor measurements. Two point sources are used to illuminate two pairs-of cc>-located wave front slope sensors. The sources and sensors are arranged to give rise to crossed optical paths. For each pair of wave front slope sensors, the output of the larger sensor is subtracted from the output of the smaller sensor. This band pass filters the smaller sensor's output. The filtered …
Increasing The Corrected Field Of View Of An Adaptive Optical Telescope, Dustin C. Johnston
Increasing The Corrected Field Of View Of An Adaptive Optical Telescope, Dustin C. Johnston
Theses and Dissertations
Current adaptive optical telescope designs use a single deformable mirror (DM) to compensate for atmospheric distortion. The corrected field of view (FOV) of an adaptive optics system could be increased through the use of multiple DMs optically conjugated to corresponding planes which sample the turbulence region in altitude. Often, the atmospheric turbulence responsible for the degradation of telescope images is concentrated in several layers. Each DM would correct for the component of the total wavefront in the pupil contributed by one or more layers. If the atmosphere does not possess a layered structure, the best fit of the turbulence profile …
Optimal Control Of The Starfire Beam Director, Troy V. Lanier
Optimal Control Of The Starfire Beam Director, Troy V. Lanier
Theses and Dissertations
The Starfire Beam Director (SBD) is located at the Starfire Optical Range at Kirtland Air Force Base in Albuquerque, New Mexico. The SBD capabilities include tracking celestial objects and active or passive tracking of artificial satellites to support the Phillips Laboratory Ground Based Laser Acquisition, Tracking, and Pointing (GBL ATP) program. The pointing and tracking accuracy needed to support such experiments is micron rad to sub-grad level. To accomplish this goal requires precise pointing of the massive 6 ton 1 -meter clear aperture coelostat. The purpose of this thesis is to use optimal control design techniques to develop a controller …
Design And Characterization Of Optically Pumped Vertical Cavity Surface Emitting Lasers, Richard J. Bagnell
Design And Characterization Of Optically Pumped Vertical Cavity Surface Emitting Lasers, Richard J. Bagnell
Theses and Dissertations
Vertical Cavity Surface Emitting Lasers (VCSELs) are a form of semiconductor laser which have their cavity oriented orthogonally to the plane of the wafer. The orientation necessitates short cavities, highly reflective mirrors and a relatively high gain/loss ratio. Even so, the resultant superior exit beam characteristics and the tight packing density of the finished lasers provide strong motivation for pursuing the growth of these structures. This thesis details the design of an optically pumped InGaAs multiple quantum well periodic gain structure VCSEL with a 950 nm lasing wavelength. These growths were to be a first attempt at VCSEL construction, so …
The Effect Of An Adaptive Optical System's Spatio-Temporal Response On Imaging Performance, Patrick M. Harrington
The Effect Of An Adaptive Optical System's Spatio-Temporal Response On Imaging Performance, Patrick M. Harrington
Theses and Dissertations
Ideally, an adaptive optical control system would have instantaneous temporal response and infinite spatial bandwidth. In real systems, the response time of the adaptive optical control system is limited by the integration time of the wave front sensor, the computational time of the control algorithm, and the actuator response time. Additionally, finite inter actuator spacing limits the deformable mirror's ability to reproduce spatial frequencies having a period less than twice this spacing. Although analyses general enough to account for both the temporal and spatial characteristics of the adaptive optical system exist, they are complex and require detailed information regarding the …
Laser Phase Front Measurements Using A Phase Conjugate Twyman-Green Interferometer, William J. Mandeville
Laser Phase Front Measurements Using A Phase Conjugate Twyman-Green Interferometer, William J. Mandeville
Theses and Dissertations
This study demonstrated the use of a phase conjugate TwymanGreen interferometer for measuring the phase fronts of beams emitted by infrared diode lasers operating at 830 nm. This interferometer successfully measured the phase front of a single element diode laser, providing better resolution than its conventional counterpart. The phase conjugate mirror compensated for aberrations introduced by imperfect optics in the phase conjugating arm of the interferometer. This interferometer was unable to measure the phase front of a diode array due to the array's inability to create a phase conjugate return. The array's short coherence length is believed to be the …
Processability Of Polythiophene Thin Films By Ultraviolet Photo Bleaching, Derek D. Fletcher
Processability Of Polythiophene Thin Films By Ultraviolet Photo Bleaching, Derek D. Fletcher
Theses and Dissertations
Materials possessing strong 𝜒(3) optical properties such as Polythiophene are sought for the production of optical switches. Polythiophene thin films produced by plasma enhanced CVD show a surface rms roughness of 10-15 angstroms over single square micron areas which is acceptable for wave guiding in the near IR. This research investigates permanently changing the optical properties of such a thin film by exposure to UV radiation (254 nm, 35 mW/cm2), known as photo bleaching, in hope of creating a refractive index boundary for use in total internal reflection. After 60 minutes exposure the refractive index shows …
Optical Haar Wavelet Transforms Using Computer Generated Holography, Peter G. Block
Optical Haar Wavelet Transforms Using Computer Generated Holography, Peter G. Block
Theses and Dissertations
This research introduces an optical implementation of the continuous wavelet transform to filter images. The wavelet transform is modeled as a correlation process and is implemented with a Vander Lugt correlator. The orthonormal basis set used is composed of two one-dimensional Haar functions and a two-dimensional Haar function. Each wavelet, as well as its first two dyadic scalings, is implemented with computer generated holography. The Interferogram method, which represents a function only in terms of its phase, is used to encode the wavelet functions. The results are imaged onto a CCD array and captured using a framegrabber. The optical results …
Cation Production And Reactions Induced By Electron Impact On Tetraethoxysilane, Jeremy C. Holtgrave
Cation Production And Reactions Induced By Electron Impact On Tetraethoxysilane, Jeremy C. Holtgrave
Theses and Dissertations
The production of cations by electron impact on tetraethoxysilane (TEOS) is studied with a Fourier Transform mass spectrometer (FTMS). The operating principles of FTMS are reviewed and the experimental approach to the mass calibration and cross-section measurement is discussed. The cross-sections for total and partial ionization of Si(OC2H5)4 from threshold to 50 eV are measured. Also, the ion chemistry resulting from interactions between ions and neutral TEOS is examined.
Cathodoluminescence Spectroscopy Of Zinc Germanium Phosphide Zngep2, Michael R. Gregg
Cathodoluminescence Spectroscopy Of Zinc Germanium Phosphide Zngep2, Michael R. Gregg
Theses and Dissertations
Zinc Germanium Phosphide (ZnGeP2) is a nonlinear semiconductor suitable for use as a laser tuning element over the two to six micron wavelength range. Although this crystal has been studied in the past, its luminescent properties are not yet well understood. In this present study, ZnGeP2 has been examined using cathodoluminescence spectroscopy (CL). Specifically, the spectral dependence of the CL was obtained as a function of electron beam energy, beam current and temperature. The resulting CL was found to be polarized with a peak structure that was dependent on the polarization. This peak structure observed by CL …
A Two-Dimensional Particle Simulation Of Parallel Plate Radio-Frequency (Rf) Glow Discharges, Eric J. Bennett
A Two-Dimensional Particle Simulation Of Parallel Plate Radio-Frequency (Rf) Glow Discharges, Eric J. Bennett
Theses and Dissertations
A two-dimensional model of parallel plate RF glow discharges was developed to study discharge phenomena important in plasma assisted processing of materials. The particle-in-cell method is used to calculate the trajectories of computer particles under the influence of both self and applied fields. Monte Carlo methods using the null collision technique are used to model collisions between charged particles and neutral gas atoms. Results of computer experiments are presented with special emphasis placed on ion motion in the sheath regions. Experimental results show some qualitative agreement with one-dimensional model results. Further work required to gain quantitative agreement is outlined.
Object Tracking Through Adaptive Correlation, Dennis A. Montera
Object Tracking Through Adaptive Correlation, Dennis A. Montera
Theses and Dissertations
This paper discusses the use of a correlation based system to track, an object through a series of images based on templates derived from previous image frames. The ability to track is extended to sequences which include multiple objects of interest within the field of view. This is accomplishes by comparing the height and shape of the template autocorrelation to the peaks in the correlation of the template with the next scene. The result is to identify the region in the next scene which best matches the designated target. In addition to correlation plane postprocessing, an adaptive window is used …
Electronic-To-Vibrational (E → V) Energy Transfer From Br* To Co2 And Electronic-To-Vibrational (E → V) Laser Feasibility Studies, Steven M. Katapski
Electronic-To-Vibrational (E → V) Energy Transfer From Br* To Co2 And Electronic-To-Vibrational (E → V) Laser Feasibility Studies, Steven M. Katapski
Theses and Dissertations
The energy transfer mechanism from photo-excited bromine atoms (Br(2P½)) to C02 is investigated in a pulsed fluorescence experiment. An excimer-pumped pulsed dye laser operating at 480 nm is used to photolyze molecular bromine, resulting in the creation of one excited state bromine atom, Br(2P½), and one ground state atom, Br(2P3/2). The electronically- excited bromine atoms (referred to as Br*) collide with and excite vibrational modes in the ground electronic state of CO2. Measurements are made of the Br* lifetimes and associated quenching processes, and the …