Wave-Based Subsurface Guide Star

Lehman, S K

关键词: ACOUSTICS;    EARTH ATMOSPHERE;    LASERS;    OPTIMIZATION;    POINT SOURCES;    RADAR;    REFRACTIVE INDEX;    OPTICS;    STARS;    TELESCOPES;    ULTRASONIC WAVES;   

DOI  :  10.2172/1022929
RP-ID  :  LLNL-TR-493312
PID  :  OSTI ID: 1022929
Others  :  TRN: US201118%%850

美国|英语

来源: SciTech Connect

【 摘 要 】

Astronomical or optical guide stars are either natural or artificial point sources located above the Earth's atmosphere. When imaged from ground-based telescopes, they are distorted by atmospheric effects. Knowing the guide star is a point source, the atmospheric distortions may be estimated and, deconvolved or mitigated in subsequent imagery. Extending the guide star concept to wave-based measurement systems to include acoustic, seismo-acoustic, ultrasonic, and radar, a strong artificial scatterer (either acoustic or electromagnetic) may be buried or inserted, or a pre-existing or natural sub-surface point scatterer may be identified, imaged, and used as a guide star to determine properties of the sub-surface volume. That is, a data collection is performed on the guide star and the sub-surface environment reconstructed or imaged using an optimizer assuming the guide star is a point scatterer. The optimization parameters are the transceiver height and bulk sub-surface background refractive index. Once identified, the refractive index may be used in subsequent reconstructions of sub-surface measurements. The wave-base guide star description presented in this document is for a multimonostatic ground penetrating radar (GPR) but is applicable to acoustic, seismo-acoustic, and ultrasonic measurement systems operating in multimonostatic, multistatic, multibistatic, etc., modes.