Pradyumna Kumar Swain

Silicon-based reconfigurable antennas-concepts, analysis, implementation, and feasibility

We report on an innovative reconfigurable antenna concept with significant practical relevance based on the dynamic definition of metal-like conductive plasma channels in high-resistivity silicon that are activated by the injection of DC current. The plasma channels are precisely formed and addressed using current high-resolution silicon fabrication technology. These dynamically defined plasma-reconfigurable antennas enable frequency hopping, beam shaping, and steering without the complexity of RF feed structures. This concept shows promise for delivering the performance and capabilities of a phased array, but at a reduced cost. However, challenges such as p-i-n biasing circuit complexity and their nonlinearities, as well as antenna efficiency, would still require further investigations.

Large format backside illuminated CCD imager for space surveillance

The key features and performance data of a 2560/spl times/1960-pixel split-frame-transfer imager developed for space surveillance is described. The eight-port, backside illuminated charge coupled device (CCD) features 24 /spl mu/m pixels with buried blooming drains to provide 100% optical fill-factor and >1000/spl times/ overload protection from blooming. The imaging and storage registers are strapped with metal to achieve vertical transfer clock rates >400 KHz for the 61 mm long imaging register gates. The 5 million pixel array operates at 2.7 frames/s. The monolithic focal plane includes a 32/spl times/32-pixel frame-transfer imager, with a single output, which operates at 1000 frames/s. The output ports employ a floating diffusion output circuit with responsivity of 10.5 /spl mu/V/e and noise of 7e RMS at a 1.25 MHz clock rate. The imager is photocomposed employing a combination of 5/spl times/ and 1/spl times/ lithography. The photocomposition approach is described.

Curved CCDs and their application with astronomical telescopes and stereo panoramic cameras

The creation of curved CCD’s and the mosaicing of contoured CCD’s mounted within the curved focal planes of telescopes and stereo panoramic imaging cameras introduces a revolution in optical design that greatly enhances the scientific potential of such instruments. In the alteration of the primary detection surface within the instrument’s optical system from flat to curved, and precisely matching the applied CCD’s shape to the contour of the curved focal plane, a major increase in the amount of transmittable light at various wavelengths through the system is achieved, thereby enabling multi-spectral ultra-sensitive imaging for a variety of experiments simultaneously, including autostereoscopic image acquisition. For earth-based and space-borne optical telescopes, the advent of curved CCD’s as the principle detectors provides a simplification of the telescope’s adjoining optics, reducing the number of optical elements and the occurrence of optical aberrations associated with large corrective optics used to conform to flat detectors. New astronomical experiments may be devised in the presence of curved CCD applications, including 3 dimensional imaging spectroscopy conducted over multiple wavelengths simultaneously, wide field real-time stereoscopic tracking of remote objects within the solar system at high resolution, and deep field mapping of distant objects such as galaxies with much greater precision and over larger sky regions. Stereo panoramic cameras equipped with arrays of curved CCD’s will require less optical glass and no mechanically moving parts to maintain proper stereo convergence over wider perspective viewing fields than their flat CCD counterparts, making the cameras lighter and faster in their ability to scan and record 3 dimensional objects moving within an industrial or terrain environment. Preliminary experiments conducted at the Sarnoff Corporation indicate the feasibility of curved CCD imagers with acceptable electro-optic integrity. Currently, we are in the process of evaluatingthe electro-optic performance of a curved wafer scale CCD imager. Detailed ray trace modeling and experimental electro-optical data performance obtained from the curved imager will be presented at the conference.

Curved CCD detector devices and arrays for multispectral astrophysical applications and terrestrial stereo panoramic cameras

The emergence of curved CCD detectors as individual devices or as contoured mosaics assembled to match the curved focal planes of astronomical telescopes and terrestrial stereo panoramic cameras represents a major optical design advancement that greatly enhances the scientific potential of such instruments. In altering the primary detection surface within the telescope’s optical instrumentation system from flat to curved, and conforming the applied CCD’s shape precisely to the contour of the telescope’s curved focal plane, a major increase in the amount of transmittable light at various wavelengths through the system is achieved. This in turn enables multi-spectral ultra-sensitive imaging with much greater spatial resolution necessary for large and very large telescope applications, including those involving infrared image acquisition and spectroscopy, conducted over very wide fields of view. For earth-based and space-borne optical telescopes, the advent of curved CCD’s as the principle detectors provides a simplification of the telescope’s adjoining optics, reducing the number of optical elements and the occurrence of optical aberrations associated with large corrective optics used to conform to flat detectors. New astronomical experiments may be devised in the presence of curved CCD applications, in conjunction with large format cameras and curved mosaics, including three dimensional imaging spectroscopy conducted over multiple wavelengths simultaneously, wide field real-time stereoscopic tracking of remote objects within the solar system at high resolution, and deep field survey mapping of distant objects such as galaxies with much greater multi-band spatial precision over larger sky regions. Terrestrial stereo panoramic cameras equipped with arrays of curved CCD’s joined with associative wide field optics will require less optical glass and no mechanically moving parts to maintain continuous proper stereo convergence over wider perspective viewing fields than their flat CCD counterparts, lightening the cameras and enabling faster scanning and 3D integration of objects moving within a planetary terrain environment. Preliminary experiments conducted at the Sarnoff Corporation indicate the feasibility of curved CCD imagers with acceptable electro-optic integrity. Currently, we are in the process of evaluating the electro-optic performance of a curved wafer scale CCD imager. Detailed ray trace modeling and experimental electro-optical data performance obtained from the curved imager will be presented at the conference.

Silicon based reconfigurable antennas

Efforts are under way to revolutionize antenna technology and to increase their functionality and capabilities by implementing fast reconfiguration schemes. Sarnoff Corporation (Sarnoff) has developed a novel silicon based concept for true reconfiguration based on the creation of metallic-like conductivity plasma islands that are driven by dc current. These plasma islands can be precisely formed and controlled using todays high resolution silicon technology, and are utilized to dynamically form plasma holograms for holographic antennas, enabling frequency hopping, beam steering and shaping without the complexity of feed structures, thus providing the performance and capabilities of a phased array without their price.

Deep UV sensitive high frame rate backside illuminated CCD camera developments

New applications for ultra-violet imaging are emerging in the fields of drug discovery and industrial inspection. High throughput is critical for these applications where millions of drug combinations are analyzed in secondary screenings or high rate inspection of small feature sizes over large areas is required. Sarnoff demonstrated in1990 a back illuminated, 1024 X 1024, 18 um pixel, split-frame-transfer device running at > 150 frames per second with high sensitivity in the visible spectrum. Sarnoff designed, fabricated and delivered cameras based on these CCDs and is now extending this technology to devices with higher pixel counts and higher frame rates through CCD architectural enhancements. The high sensitivities obtained in the visible spectrum are being pushed into the deep UV to support these new medical and industrial inspection applications. Sarnoff has achieved measured quantum efficiencies > 55% at 193 nm, rising to 65% at 300 nm, and remaining almost constant out to 750 nm. Optimization of the sensitivity is being pursued to tailor the quantum efficiency for particular wavelengths. Characteristics of these high frame rate CCDs and cameras will be described and results will be presented demonstrating high UV sensitivity down to 150 nm.

Ultrahigh-frame CCD imagers

This paper describes the architecture, process technology, and performance of a family of high burst rate CCDs. These imagers employ high speed, low lag photo-detectors with local storage at each photo-detector to achieve image capture at rates greater than 106 frames per second. One imager has a 64 x 64 pixel array with 12 frames of storage. A second imager has a 80 x 160 array with 28 frames of storage, and the third imager has a 64 x 64 pixel array with 300 frames of storage. Application areas include capture of rapid mechanical motion, optical wavefront sensing, fluid cavitation research, combustion studies, plasma research and wind-tunnel-based gas dynamics research.

Performance of an extended dynamic range, time delay integration charge coupled device (XDR TDI CCD) for high-intrascene dynamic range scanning

Many applications, such as industrial inspection and overhead reconnaissance benefit from line scanning architectures where time delay integration (TDI) significantly improves sensitivity. CCDs are particularly well suited to the TDI architecture since charge is transferred virtually noiselessly down the column. Sarnoffs TDI CCDs have demonstrated extremely high speeds where a 7200 x 64, 8 um pixel device with 120 output ports demonstrated a vertical line transfer rate greater than 800 kHz. The most recent addition to Sarnoffs TDI technology is the implementation of extended dynamic range (XDR) in high speed, back illuminated TDI CCDs. The optical, intrascene dynamic range can be adjusted in the design of the imager with measured dynamic ranges exceeding 2,000,000:1 with no degradation in low light performance. The device provides a piecewise linear response to light where multiple slopes and break points can be set during the CCD design. A description of the device architecture and measured results from fabricated XDR TDI CCDs are presented.

Backside-illuminated 6.6-μm pixel video-rate CCDs for scientific imaging applications

A family of backside illuminated CCD imagers with 6.6 micrometers pixels has been developed. The imagers feature full 12 bit (> 4,000:1) dynamic range with measured noise floor of < 10 e RMS at 5 MHz clock rates, and measured full well capacity of > 50,000 e. The modulation transfer function performance is excellent, with measured MTF at Nyquist of 46% for 500 nm illumination. Three device types have been developed. The first device is a 1 K X 1 K full frame device with a single output port, which can be run as a 1 K X 512 frame transfer device. The second device is a 512 X 512 frame transfer device with a single output port. The third device is a 512 X 512 split frame transfer device with four output ports. All feature the high quantum efficiency afforded by backside illumination.