Mr. Thomas A. Underwood Profile

Thomas A. Underwood

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Publications (4)

Proceedings Article | 13 December 2020 Poster + Paper

Characteristics and performances of an interferometric Doppler imager installed at the 188 cm telescope of Okayama Observatory

François-Xavier Schmider, Julien Dejonghe, Tristan Guillot, Masahiro Ikoma, Patrick Boumier, Bun'ei Sato, Jason Jackiewicz, Hideyuki Izumiura, Hidekazu Hanayama, Lyu Abe, Ivan Gonçalves, Carole Gouvret, Yan Fantéï-Caujolle, Frédéric Morand, Olivier Preis, Jean-Pierre Rivet, Thierry Appourchaux, Jean-Christophe Leclec'h, Hervé Ballans, François Langlet, Frédéric Baudin, Yuhiko Aoyama, Kiyoe Kawaushi, Takashi Horiuchi, Patrick Gaulme, David Voelz, Thomas Underwood

Proceedings Volume 11447, 114473D (2020) https://doi.org/10.1117/12.2559448

KEYWORDS: Telescopes, Doppler effect, Jupiter, Imaging systems, Observatories, Planets, Interferometry, Atmospheric sensing, Acoustics, Wind measurement

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Proceedings Article | 11 May 2018 Presentation + Paper

Exploring mitigation of image blur due to atmospheric turbulence by utilizing multiple sensors to achieve optical path diversity

Thomas Underwood, Joe Stufflebeam, David Soules, Mark Kircher, Mark Roberts, Joachim Lohn-Jaramillo, Geoff Knox, Jason Shankle

Proceedings Volume 10650, 1065005 (2018) https://doi.org/10.1117/12.2309412

KEYWORDS: Cameras, Atmospheric turbulence, Missiles, Turbulence, Sensors, Atmospheric optics, Multiplexing, Image sensors, Image quality, Software development

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Many atmospheric turbulence deblurring techniques estimate an inverse filter by making assumptions that constrain the mathematical spaces in which an unknown signal and convolving function must reside. Restoration of scene content after imaging through terrestrial imaging paths is an area of active experimentation and development for both real-time feature extraction and post-process data reduction. Static scenes present opportunities for algorithms that exploit the temporal diversity of the atmospheric path since motion of scene content at the image plane over multiple frames may be attributed to a randomly varying blur kernel. This allows for the estimation of inverse filters that can be used to deblur the image. However, when objects in the scene move relative to one another across multiple image frames it complicates an already computationally demanding process. Techniques to compensate for the motion of one or more features can be used, but if the image fidelity is insufficient to detect a moving feature in the first place or the number of features (e.g. fragmentation from an impact or explosion) is very large, motion compensation techniques may break down or become impractical. In this paper we explore using multiple, synchronized optical systems with sufficient spatial separation to provide the optical path turbulence diversity required by many deblurring algorithms. This reduces or eliminates many constraints on object motion when performing reconstructions. We present deblurred imagery examples from an experimental setup that leverages spatially diverse, optical path turbulence and compare the results with the traditional approach of utilizing single path, temporal diversity when performing image reconstructions. Our results demonstrate that: (1) useful deblurring is possible with a single “set” of images simultaneously collected through diverse optical paths, (2) a combination of temporal and spatial diversity of image collection can be a useful “hybrid” approach, and (3) opportunistic weighting of concurrent frames according to image quality can enhance the deblurring results.

Proceedings Article | 5 September 2017 Paper

Adaptation of Dunn Solar Telescope for Jovian Doppler spectro imaging

Thomas Underwood, David Voelz, François-Xavier Schmider, Jason Jackiewicz, Julien Dejonghe, Yves Bresson, Robert Hull, Ivan Goncalves, Patrick Gualme, Frédéric Morand, Olivier Preis

Proceedings Volume 10401, 104010Y (2017) https://doi.org/10.1117/12.2275909

KEYWORDS: Doppler effect, Solar telescopes, Planets, Acoustics, Video processing, Telescopes, Interferometry, Interferometers, Imaging systems, Mach-Zehnder interferometers

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Proceedings Article | 17 September 2013 Paper

Wave optics approach for incoherent imaging simulation through distributed turbulence

Thomas Underwood, David Voelz

Proceedings Volume 8877, 88770G (2013) https://doi.org/10.1117/12.2025396

KEYWORDS: Turbulence, Computer simulations, Atmospheric propagation, Wave propagation, Light wave propagation, Imaging systems, Light, Atmospheric turbulence, Point spread functions, Optical simulations

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