Master's Defense - Andrew J Stokes
Nov/24/2009 08:00 Filed in: Events
IMPROVING MID-FREQUENCY CONTRAST IN SPARSE APERTURE OPTICAL IMAGING SYSTEMS BASED UPON THE GOLAY-N FAMILY OF ARRAYS
Name: Stokes, Andrew James
Advisor: Dr. Bradley D. Duncan
November 24, 2009
8:00am CPC 580
All are invited
Name: Stokes, Andrew James
Advisor: Dr. Bradley D. Duncan
November 24, 2009
8:00am CPC 580
All are invited
ABSTRACT
Sparse aperture imaging systems are capable of producing high resolution images while maintaining a small overall light collection area compared to a fully filled aperture yielding the same resolution. This is advantageous for applications where size, volume, weight and/or cost are important. However, sparse aperture systems pay the penalty of reduced contrast at midband spatial frequencies. The focus of this work has been on increasing the midband contrast of sparse aperture imaging systems based on the Golay-N family of arrays. These arrays are of interest due to their compact, non-redundant autocorrelations. The modulation transfer function provides a quantitative measure of both the resolution and contrast of an imaging system and, along with an average relative midband contrast metric, will be used to compare perturbations to the Golay arrays. Numerical calculations have been performed to investigate the behavior of Golay-9 and -12 arrays into which autocorrelation redundancy has been introduced. An increase in midband average relative contrast of over 55% was experimentally verified for the Golay-9 array.
Sparse aperture imaging systems are capable of producing high resolution images while maintaining a small overall light collection area compared to a fully filled aperture yielding the same resolution. This is advantageous for applications where size, volume, weight and/or cost are important. However, sparse aperture systems pay the penalty of reduced contrast at midband spatial frequencies. The focus of this work has been on increasing the midband contrast of sparse aperture imaging systems based on the Golay-N family of arrays. These arrays are of interest due to their compact, non-redundant autocorrelations. The modulation transfer function provides a quantitative measure of both the resolution and contrast of an imaging system and, along with an average relative midband contrast metric, will be used to compare perturbations to the Golay arrays. Numerical calculations have been performed to investigate the behavior of Golay-9 and -12 arrays into which autocorrelation redundancy has been introduced. An increase in midband average relative contrast of over 55% was experimentally verified for the Golay-9 array.