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Multi-parameter illumination techniques for millimeter wave imaging

Monday, 29 March, 2010 - 10:00
Campus: Brussels Humanities, Sciences & Engineering campus
Lixiao Zhang
phd defence

Millimeter wave imaging is a very promising technology for concealed
weapon detection that is becoming a compulsory measure to enhance
aviation security. Millimeter wave imaging has two fundamental
realizations, passive and active. In indoor environments, such as the
airports, active imaging has the advantage of high image contrast over
passive imaging; however it suffers from coherent artifacts of glint and
speckle. In this work, we study material phenomenology, component
technologies, quasi-optics design, and imaging system architectures, which
need to be understood for building an imaging system. We present
experimental imaging systems capable of providing multi-parameter,
frequency, angle and phase, illumination. Through theoretical analyses and
experiments, we investigate the cause of glint and speckle (interference
noise), and show how multi-parameter illumination techniques can reduce
these artifacts. As far as we know, this work is the first to experimentally
prove the angle and phase diversity concepts for speckle reduction in
millimeter wave imaging field. We also find that processing multispectral
millimeter wave images can extract extra scene features and enhance object
appearance, resulting in greatly improved image quality.