Speckle Contrast

In

Figure: Concealed Knife. (a) Image
of a knife under a thin brown robe at 632
GHz. (c) Co-added image of a knife taken
at 16 independent angles. The quantitat-
ive traces below each image show the sig-
nal along the blue line in each image. Th-
ese graphs show that the speckle contrast
noise is reduced by (16)1/2=4 by the ave-
raging over the 16 independent images.

the speckle size is comparable to the angular size of many of the small features in the atrium, and the evaluation of the speckle reduction requires a more formal approach.

Figure: Physics Building Atrium GHz
Image. (a)218.4 GHz image of the atrium
of the Physics Building at Ohio State Univer-
sity with multimode illumination, but without
modulated mode-mixing and (b)with modul-
ated mode mixing. The colored boxes show
areas for which speckle statistics have been
calculated.

Figure: Concealed Knife. (a) Image
of a knife under a thin brown robe at 632
GHz. (c) Co-added image of a knife taken
at 16 independent angles. The quantitat-
ive traces below each image show the sig-
nal along the blue line in each image. Th-
ese graphs show that the speckle contrast
noise is reduced by (16)1/2=4 by the ave-
raging over the 16 independent images.