Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 56 for “"Focal Length"”.
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Modulation transfer function and the role of focal length of a photogrammetric camera in image generation.
… This research investigates the role of focal length of a photogrammetric camera in image generation through the criterion of Modulation Transfer Function. A comparative study is made of the MTF obtained from two lens cones under various aperture settings, detail size and light …
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Metric aspects of zoom vision
… camera systems equipped with 12.5-75mm variable focal length lenses. Specific objectives included: identifying distortion parameters that effect 3-D positioning accuracy; developing a procedure for modeling the changes in distortion parameters that occur as the focal length of a zoom lens …
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An investigation of early radiation damage in exposed eye-lenses of rainbow trout
… 2.210 Gy with low-energy X-rays of 40 kV. Laser focal analysis was used to track changes in focal lengths across the lenses post-irradiation. The purpose of this study was to determine whether focal length variability (FLV) could give an indication of the early effects of radiation on lens …
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Liquid lens beam steering and environmental testing for the miniature optical steered antenna for inter-satellite communication
… are lenses that can non-mechanically alter focal length based on an applied voltage or current. We evaluate two commercial liquid lens manufacturers, Corning Varioptic and Optotune. Corning Varioptic lenses rely on the principle of electrowetting for lens actuation, while Optotune lenses are …
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Study of photogrammetric self-calibration adjustment method
… camera and test configuration considered, the focal length was recovered to within two percent, and the principal point location was recovered to wi thin O. 3 to twelve percent. When the computer generated data was used, the focal length and principal point offset were recovered to within 0.2 …
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Analysis of a laser induced plasma in high pressure SF6 gas for high-voltage, high-current switching
… in order to quantify parameters such as spark length and plasma temperature. The laser spark is created through a focusing lens by the fourth-harmonic (266nm) of a 5ns FWHM pulsed Nd:YAG laser with 30mJ maximum energy output. Several diagnostic methods are used to analyze the laser spark. …
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Lens Fabrication by Accelerated Phase-Change for Mobile Multimodal Microscopic Imaging
… fabrication of microscope lenses with precise focal length control. The lens can be self-adhered onto smartphone cameras and result in an imaging resolution of 1 µm, sufficient for biological cell imaging. The optical power of the lens can be finely controlled by varying printing variables …
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Explorations in Monocular Distance And Ranging (MODAR) Techniques for Real-World Applications
… image of the most in-focus pixels from a focal stack of images collected while the camera was in motion. Following this, the depth retrieval algorithm was tested on a geared lens setup in which a gear-driven fixed focal length lens was attached to a camera and driven such that the distance …
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Tunable Liquid Crystal Photonic Devices
… is to develop a system with continuously tunable focal length. A conventional zooming system controls the lens distance by mechanical motion along the optical axis. This mechanical zooming system is bulky and power hungry. To overcome the bulkiness, in Chap. 4 we developed an electrically …
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Set up of a short magnetic lens electron spectrometer and investigation of cesium-137 and thulium-170 decay.
… lens electron spectrometer of about 21cm focal length was set up and used during the course of this investigation. A Cs137 source was mainly used as a calibration source since decay spectrum is well understood. The magnetic field was varied in the range such that the electrons of 400 to …
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Computer simulations to calculate energy flux and image size on a receiver for different reflector geometries using caustics
… on the target to the ratio of aperture size and focal length of a model heliostat.
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Dynamic and stimuli-responsive multi-phase emulsion droplets for optical components
… dynamic compound micro-lenses with adjustable focal length that is continuously variable from converging lenses to diverging lenses.
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Exploring and evaluating methods of actuating an active lens
… electromagnetic actuator was able to generate a focal power range of 11.9 to 19.2 diopters (52 to 84mm focal length range), but a high power consumption led to problems with heating the internal components of the active lens assembly. In the EAP method, a lower power consumption proved to be a …
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Applying synthetic aperture, coded excitation, and tissue harmonic imaging techniques to allow ultrasound imaging with a virtual source
… transducer’s focus. Therefore, having only one focal length places a great restriction on ultrasound imaging, especially with a single-element transducer. To extend the region of focus, three techniques were examined. The first was the synthetic aperture focusing technique (SAFT), a well-studied …
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A novel compact Shearographic NDT system
… only be increased by using a relatively small focal length camera lens which results in having to increase the size of the shearing optics. This would make the compact Shearographic device much larger which is counter-productive since technology enables/directs research and development toward …
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Analyzing perspective views of a wire frame object model
… image: a photograph taken by a camera with fixed focal length, is given, and a three dimensional wire frame object model is also given. Each object in the model is composed of planar arcs. The arc is bounded by connected line segments or conics. The input image is a simulated photographs of some …
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Optimizing heat transfer in a solar parabolic trough collector absorber
… a solar tracking mechanism, a 300-mm focal length, a 6.3-m² aperture area, and uses water as the heat transfer fluid (HTF). The first optimization approach explored the impacts of external fins on solar absorbed tubes. Results revealed that finned tubes significantly outperformed …
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Design and Development of Advanced Adaptive Polymer Lenses
… lenses were constructed for visible, short- wavelength infrared (SWIR), and middle-wavelength infrared (MWIR)applications. The lenses are implemented in a variety of tactical imaging systems to demonstrate their performance. A process was developed that defines the allowable fabrication …
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