Dale E. Gary

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Over the past 5 years, there has been a significant interest in employing terahertz (THz) technology, spectroscopy and imaging for security applications. There are three prime motivations for this interest: (a) THz radiation can detect concealed weapons since many non-metallic, non-polar materials are transparent to THz radiation; (b) target compounds such(More)
Rapid voltage-controlled phase modulation of cw terahertz (THz) radiation is demonstrated. By transmitting an infrared beam through a lithium niobate phase modulator the phase of the THz radiation, which is generated by the photomixing of two infrared beams, can be directly modulated through a 2pi phase shift. The 100 kHz modulation rate that is(More)
In this paper, we study solar microflares using the coordinated hard X-ray and microwave observations obtained by the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI ) during its open-shutter operation mode and the Owens Valley Solar Array (OVSA). The events in our study are selected in the energy range of 12–25 keVand are relatively large(More)
The stand-off imaging properties of a terahertz (THz) interferometric array are examined. For this application, the imaged object is in the near-field region limit of the imaging array. In this region, spherical and circular array architectures can compensate for near-field distortions and increase the field of view and depth of focus. Imaging of THz point(More)
A radio frequency interference (RFI) excision algorithm based on spectral domain statistics is proposed and implemented in software. The algorithm requires the use of two memory buffers, S1 and S2, in which the first two powers of M power spectral density (PSD) estimates, obtained via Fast Fourier Transform (FFT), are accumulated and used to form a Spectral(More)
Most methods of imaging in the terahertz ~THz! spectral region utilize either pulsed-laser sources or require the THz generation and detection sources to be phase coherent. The application of interferometric imaging to the THz range is described. Interferometric imaging offers considerable advantages in this regard due to its ability to image with only a(More)
The imaging properties of planar, spherical, and circular interferometric imaging arrays are examined in the near-field region limit. In this region, spherical and circular array architectures can compensate for near-field distortions and increase the field of view and depth of focus. The application of near-field interferometric imaging to the Terahertz(More)
Recently, there has been a significant interest in employing Terahertz (THz) technology, spectroscopy and imaging for standoff detection applications. There are three prime motivations for this interest: (a) THz radiation can detect concealed weapons since many non-metallic, non-polar materials are transparent to THz radiation, (b) target compounds such as(More)
We show that the application of ultrafast techniques, especially terahertz time-domain spectroscopy, allows simultaneous measurements of material thickness and optical constants from transmission measurements, by analyzing not only the phase difference between the main terahertz pulse through the medium but also the subsequent multireflection pulse (an(More)