Freely propagating terahertz pulses are usually measured by sampling techniques such as photoconductive antenna or electro-optical sampling. Although these sampling techniques provide good signal-to-noise ratios and adequate temporal resolution, they cannot be used for measurement on a single-shot basis. The present invention provides a system for measuring a terahertz frequency pulse propagating in a free-space optical path using an optical streak camera and an electro-optical modulator.
This technology couples the physical layer characteristics of wireless networks with key generation algorithms. It is based on the wireless communication phenomenon known as the principle of reciprocity which states that in the absence of interference both transmitter and receiver experience the same signal envelope. Signal envelope information can provide to the two transceivers two correlated random sources that provide sufficient amounts of entropy which can be used to extract a cryptographic key.
Electro-optic crystals and photoconductive dipole antennas have been widely used in terahertz (THz) time-domain spectroscopy and related imaging applications. In the standard apparatus used for THz time-domain spectroscopy a separate transmitter and receiver are used for the emission and detection of the THz signal. Because detection is the reverse process of emission, the transmitter and the receiver can be identical devices.
This invention is directed to a highly accurate and efficient method and algorithm, namely the Dual-Bootstrap Iterative Closest Point algorithm, for performing image registration generally and retinal image registration in particular. Retinal image registration is challenging. The images are projections of a curved surface taken from a wide range of viewpoints using an un-calibrated camera. The non-vascular surface of the retina is homogeneous in healthy retinas, and exhibits a variety of pathologies in unhealthy retinas.