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Title: Speckle in Active Millimeter-Wave and Terahertz Imaging and Spectroscopy

Abstract

Wideband millimeter-wave imaging techniques and systems have been developed at PNNL for concealed weapon detection and other applications. These techniques evolved from single-frequency millimeter-wave holographic imaging methods to wideband three-dimensional planar and cylindrical techniques and systems. The single-frequency holographic method was derived from optical and ultrasonic holography techniques. Speckle is highly significant in this case, and is caused by constructive and destructive interference from multiple scattering locations or depths within a single resolution cell. The wideband three-dimensional techniques developed at PNNL significantly reduce the speckle effect through the use of high depth resolution obtained from the wide bandwidth of the illumination. For these techniques, speckle can still be significant in some cases and affect image quality. In this paper, we explore the situations in which speckle occurs and it's relationship to lateral and depth resolution. This will be accomplished through numerical simulation and demonstrated in actual imaging results. Speckle may also play a significant role in altering reflection spectra in wideband terahertz spectra. Reflection from rough surfaces will generate speckle, which will result in significant variation in the reflection spectrum as measured over very wide bandwidths. This effect may make if difficult to interpret spectral absorption features from general reflectancemore » data. In this paper, physical optics numerical simulation techniques will be used to model the reflection from arbitrary random surfaces and explore the effect of the surface on the reflection spectra and reconstructed image. Laboratory imaging and numerical modeling results in the millimeter-wave through the terahertz frequency ranges are presented.« less

Authors:
; ;
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
989064
Report Number(s):
PNNL-SA-54201
TRN: US201019%%181
DOE Contract Number:
AC05-76RL01830
Resource Type:
Conference
Resource Relation:
Conference: Passive Millimeter-Wave Imaging Technology X, 6548:Paper No. 654809
Country of Publication:
United States
Language:
English
Subject:
47 OTHER INSTRUMENTATION; HOLOGRAPHY; SPECTROSCOPY; WEAPONS; DETECTION; IMAGES; NOISE; RESOLUTION; COMPUTERIZED SIMULATION; SURFACES; ROUGHNESS; REFLECTION; Millimeter Waves; Cylindrical Imaging; Imaging; Holography; Personnel Surveillance; Screening

Citation Formats

Sheen, David M., McMakin, Douglas L., and Hall, Thomas E.. Speckle in Active Millimeter-Wave and Terahertz Imaging and Spectroscopy. United States: N. p., 2007. Web. doi:10.1117/12.721323.
Sheen, David M., McMakin, Douglas L., & Hall, Thomas E.. Speckle in Active Millimeter-Wave and Terahertz Imaging and Spectroscopy. United States. doi:10.1117/12.721323.
Sheen, David M., McMakin, Douglas L., and Hall, Thomas E.. Sun . "Speckle in Active Millimeter-Wave and Terahertz Imaging and Spectroscopy". United States. doi:10.1117/12.721323.
@article{osti_989064,
title = {Speckle in Active Millimeter-Wave and Terahertz Imaging and Spectroscopy},
author = {Sheen, David M. and McMakin, Douglas L. and Hall, Thomas E.},
abstractNote = {Wideband millimeter-wave imaging techniques and systems have been developed at PNNL for concealed weapon detection and other applications. These techniques evolved from single-frequency millimeter-wave holographic imaging methods to wideband three-dimensional planar and cylindrical techniques and systems. The single-frequency holographic method was derived from optical and ultrasonic holography techniques. Speckle is highly significant in this case, and is caused by constructive and destructive interference from multiple scattering locations or depths within a single resolution cell. The wideband three-dimensional techniques developed at PNNL significantly reduce the speckle effect through the use of high depth resolution obtained from the wide bandwidth of the illumination. For these techniques, speckle can still be significant in some cases and affect image quality. In this paper, we explore the situations in which speckle occurs and it's relationship to lateral and depth resolution. This will be accomplished through numerical simulation and demonstrated in actual imaging results. Speckle may also play a significant role in altering reflection spectra in wideband terahertz spectra. Reflection from rough surfaces will generate speckle, which will result in significant variation in the reflection spectrum as measured over very wide bandwidths. This effect may make if difficult to interpret spectral absorption features from general reflectance data. In this paper, physical optics numerical simulation techniques will be used to model the reflection from arbitrary random surfaces and explore the effect of the surface on the reflection spectra and reconstructed image. Laboratory imaging and numerical modeling results in the millimeter-wave through the terahertz frequency ranges are presented.},
doi = {10.1117/12.721323},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Sun Apr 01 00:00:00 EDT 2007},
month = {Sun Apr 01 00:00:00 EDT 2007}
}

Conference:
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