All-optical high speed NOR gate based on two photon absorption in silicon wire waveguides

We demonstrate for the first time an all-optical logic NOR gate in submicron size silicon wire waveguides. High speed operation at equivalent 80Gbps data rate was achieved using pump induced non-degenerate two-photon absorption inside the waveguides. The device requires low pulse energy (few pJ) for logic gate operation. (C) 2005 Optical Society of America

SUAVE: Integrating UAV video using a 3D model

Controlling an unmanned aerial vehicle (UAV) requires the operator to perform continuous surveillance and path planning. The operator's situation awareness degrades as an increasing number of surveillance videos must be viewed and integrated. The Picture-in-Picture display (PiP) provides a solution for integrating multiple UAV camera video by allowing the operator to view the video feed in the context of surrounding terrain. The experimental SUAVE (Simple Unmanned Aerial Vehicle Environment) display extends PiP methods by sampling imagery from the video stream to texture a 3D map of the terrain. The operator can then inspect this imagery using world in miniature (WIM) or fly-through methods. We investigate the properties and advantages of SUAVE in the context of a search mission with 3 UAVs

Studies of Minerals, Organic and Biogenic Materials through Time-Resolved Raman Spectroscopy

A compact remote Raman spectroscopy system was developed at NASA Langley Research center and was previously demonstrated for its ability to identify chemical composition of various rocks and minerals. In this study, the Raman sensor was utilized to perform time-resolved Raman studies of various samples such as minerals and rocks, Azalea leaves and a few fossil samples. The Raman sensor utilizes a pulsed 532 nm Nd:YAG laser as excitation source, a 4-inch telescope to collect the Raman-scattered signal from a sample several meters away, a spectrograph equipped with a holographic grating, and a gated intensified CCD (ICCD) camera system. Time resolved Raman measurements were carried out by varying the gate delay with fixed short gate width of the ICCD camera, allowing measurement of both Raman signals and fluorescence signals. Rocks and mineral samples were characterized including marble, which contain CaCO3. Analysis of the results reveals the short (approx.10-13 s) lifetime of the Raman process, and shows that Raman spectra of some mineral samples contain fluorescence emission due to organic impurities. Also analyzed were a green (pristine) and a yellow (decayed) sample of Gardenia leaves. It was observed that the fluorescence signals from the green and yellow leaf samples showed stronger signals compared to the Raman lines. Moreover, it was also observed that the fluorescence of the green leaf was more intense and had a shorter lifetime than that of the yellow leaf. For the fossil samples, Raman shifted lines could not be observed due the presence of very strong short-lived fluorescence

Design and Build a Compact Raman Sensor for Identification of Chemical Composition

A compact remote Raman sensor system was developed at NASA Langley Research Center. This sensor is an improvement over the previously reported system, which consisted of a 532 nm pulsed laser, a 4-inch telescope, a spectrograph, and an intensified charge-coupled devices (CCD) camera. One of the attractive features of the previous system was its portability, thereby making it suitable for applications such as planetary surface explorations, homeland security and defense applications where a compact portable instrument is important. The new system was made more compact by replacing bulky components with smaller and lighter components. The new compact system uses a smaller spectrograph measuring 9 x 4 x 4 in. and a smaller intensified CCD camera measuring 5 in. long and 2 in. in diameter. The previous system was used to obtain the Raman spectra of several materials that are important to defense and security applications. Furthermore, the new compact Raman sensor system is used to obtain the Raman spectra of a diverse set of materials to demonstrate the sensor system's potential use in the identification of unknown materials

Standoff Ultra-Compact Micro-Raman Sensor for Planetary Surface Explorations

We report the development of an innovative standoff ultracompact micro-Raman instrument that would solve some of the limitations of traditional micro-Raman systems to provide a superior instrument for future NASA missions. This active remote sensor system, based on a 532 nm laser and a miniature spectrometer, is capable of inspection and identification of minerals, organics, and biogenic materials within several centimeters (220 cm) at a high 10 m resolution. The sensor system is based on inelastic (Raman) light scattering and laser-induced fluorescence. We report on micro-Raman spectroscopy development and demonstration of the standoff Raman measurements by acquiring Raman spectra in daylight at a 10 cm target distance with a small line-shaped laser spot size of 17.3 m (width) by 5 mm (height)

Remote Raman Sensor System for Testing of Rocks and Minerals

Recent and future explorations of Mars and lunar surfaces through rovers and landers have spawned great interest in developing an instrument that can perform in-situ analysis of minerals on planetary surfaces. Several research groups have anticipated that for such analysis, Raman spectroscopy is the best suited technique because it can unambiguously provide the composition and structure of a material. A remote pulsed Raman spectroscopy system for analyzing minerals was demonstrated at NASA Langley Research Center in collaboration with the University of Hawaii. This system utilizes a 532 nm pulsed laser as an excitation wavelength, and a telescope with a 4-inch aperture for collecting backscattered radiation. A spectrograph equipped with a super notch filter for attenuating Rayleigh scattering is used to analyze the scattered signal. To form the Raman spectrum, the spectrograph utilizes a holographic transmission grating that simultaneously disperses two spectral tracks on the detector for increased spectral range. The spectrum is recorded on an intensified charge-coupled device (ICCD) camera system, which provides high gain to allow detection of inherently weak Stokes lines. To evaluate the performance of the system, Raman standards such as calcite and naphthalene are analyzed. Several sets of rock and gemstone samples obtained from Ward s Natural Science are tested using the Raman spectroscopy system. In addition, Raman spectra of combustible substances such acetone and isopropanol are also obtained. Results obtained from those samples and combustible substances are presented