Dissertation/Thesis Abstract

Pushing the limits of imaging using patterned illumination
by Rangarajan, Prasanna, Ph.D., Southern Methodist University, 2014, 218; 3624926
Abstract (Summary)

The image captured by an imaging system is subject to constraints imposed by the wave nature of light and the geometry of image formation. The former limits the resolving power of the imager while the latter results in a loss of size and range information. The body of work presented in this dissertation strives to overcome the aforementioned limits. The suite of techniques and apparatus ideas disclosed in the work afford imagers the unique ability to capture spatial detail lost to optical blur, while also recovering range information.

A recurring theme in the work is the notion of imaging under patterned illumination. The Moiré fringes arising from the heterodyning of the object detail and the patterned illumination, are used to improve the resolving power of the imager. The deformations in the phase of the detected illumination pattern, aid in the recovery of range information.

The work furnishes a comprehensive mathematical model for imaging under patterned illumination that accommodates blur due to the imaging/illumination optics, and the perspective foreshortening observed at macroscopic scales. The model discloses the existence of a family of active stereo arrangements that jointly support super resolution (improvement of resolving power) and scene recovery (recovery of range information).

The work also presents a new description of the theoretical basis for super resolution. The description confirms that an improvement in resolving power results from the computational engineering of the imager impulse response. The above notion is explored further, in developing a strategy for engineering the impulse response of an imager, using patterned illumination. It is also established that optical aberrations are not an impediment to super resolution.

Furthermore, the work advances the state-of-the-art in scene recovery by establishing that a broader class of sinusoidal patterns may be used to recover range information, while circumventing the extensive calibration process employed by current approaches.

The work concludes by examining an extreme example of super resolution using patterned illumination. In particular, a strategy that overcomes the severe anisotropy in the resolving power of a single-lens imager is examined. Spatial frequency analysis of the reconstructed image confirms the effectiveness of lattice illumination in engineering a computational imager with near isotropic resolving power.

Indexing (document details)
Advisor: Papamichalis, Panos E., Christensen, Marc P.
Commitee: Milojkovic, Predrag, Rajan, Dinesh, Zhou, Yunkai
School: Southern Methodist University
Department: Electrical Engineering
School Location: United States -- Texas
Source: DAI-B 75/10(E), Dissertation Abstracts International
Source Type: DISSERTATION
Subjects: Electrical engineering, Optics
Keywords: Computational imaging, Point spread function engineering, Profilometry, Structured illumination, Structured light, Super resolution
Publication Number: 3624926
ISBN: 9781303992056
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