Polarization difference imaging : a means for seeing through scattering media / J. Scott Tyo.

Format:

Book

Manuscript

Microformat

Thesis/Dissertation

Author/Creator:

Tyo, J. Scott.

Contributor:

University of Pennsylvania.

Language:

English

Subjects (All):

Penn dissertations--Electrical engineering.

Electrical engineering--Penn dissertations.

Local Subjects:

Penn dissertations--Electrical engineering.

Electrical engineering--Penn dissertations.

Physical Description:

x, 175 pages : illustrations ; 29 cm

Production:

1997.

Summary:

Reliable optical imaging in scattering media has been a goal of many researchers seeking to find solutions to the problems presented when imaging underwater, in rain and/or fog, or in human tissue. Many elegant techniques have already been discovered that improve the images of scenes obtained in scattering media, most of which require expensive hardware and precise control of the physical features of the system. Inspired by a hypothesis about the retina of the green sunfish (Lepomis cyanellus), polarization difference imaging (PDI) has been employed to aid in the detection and identification of polarizing targets embedded in a scattering medium. This novel technique differs from other imaging methods in its simplicity: precise control of the timing and coherence of illumination is absolutely unnecessary. The current work provides a thorough account of the development of PDI to date. Images are presented of targets that have spatially-varying, polarization-dependent reflectances, and PDI is demonstrated to reveal target features that are undetectable with conventional means, even when the image forming light has a low degree of polarization. Common mode rejection, differential mode amplification, and narrowing of the point spread function are all explored as factors contributing to the increase in detectability observed with PDI.

While use of polarization differencing alone does reveal information about particular scenes, PDI can also serve as the basis for a more complex imaging or vision system. A geometric model for representing a polarization perceptual space is formulated, and parallels between polarization and color vision that have been described previously are investigated and expanded upon. A representational scheme is proposed that maps polarization information into colorimetric parameters so that human observers can readily see the polarization-dependent features of an image that are otherwise not apparent to the human vision system. In addition to serving as the basis for an engineered imaging system, the geometric model described herein may lend insight into the operation of polarization sensitive vision systems that have reportedly been discovered in nature.

Notes:

Thesis (Ph.D. in Electrical Engineering) -- University of Pennsylvania, 1997.

Includes bibliographical references and index.

Local Notes:

University Microfilms order no.: 97-27305.

OCLC:

187470554