title: Comparison of speckle reduction diversity tools for active millimeter-wave imaging.
abstract: Imaging concealed objects with millimeter-wave coherent radiation is accompanied by speckle. Like all interference phenomena, speckle depends on three light parameters of the millimeter-wave laser beam--phase, wavelength, and angle of incidence--and can be reduced by the diversity of these three parameters. Diversity tools to improve images of concealed objects have been compared. We report measurements, simulations, and image reconstruction results over the whole W-band (75-110 GHz) and demonstrate where each tool works the best. Multiphase diversity is successful in reducing speckle contrast: multiangle to improve the image quality, and multispectral to recognize a small object's features. A simple postprocessing eliminates the areas still covered by interference.
authors.affiliation: Lab for Micro- and Photonelectronics, Electronics and Information Processing Department, Vrije Universiteit Brussel, Brussels, Belgium. ijager@etro.vub.ac.be
authors.forename: Irina
authors.initials: I
authors.lastname: Jaeger
authors.forename: Johan
authors.initials: J
authors.lastname: Stiens
authors.forename: Lixao
authors.initials: L
authors.lastname: Zhang
authors.forename: Saiful
authors.initials: S
authors.lastname: Islam
authors.forename: Gaetan
authors.initials: G
authors.lastname: Koers
authors.forename: Roger
authors.initials: R
authors.lastname: Vounckx