Radio frequency vacuum microelectronics combines the advantages of electron transport in vacuum with gated electron emission structures derived from solid-state microfabrication. The advent of practical gated vacuum e...
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ISBN:
(纸本)0780337867
Radio frequency vacuum microelectronics combines the advantages of electron transport in vacuum with gated electron emission structures derived from solid-state microfabrication. The advent of practical gated vacuum emitters of micron size will have a strong impact on rf source technology. Next-generation rf amplifiers incorporating microfabricated emitters will allow amplifier designs that minimize the need for high-voltage power supplies, complex modulating circuitry, and the heavy magnets common with linear beam tubes. One attractive application for such efficient compact amplifiers is as the vacuum power booster of a microwave power module, a device that combines a solid-state preamplifier with a low-gain vacuum amplifier for efficiency. Program goals are to create a 50 W 10 GHz amplifier with 10 dB gain and efficiency exceeding 50%. We will survey the requirements placed on field emitter arrays for performance in a microwave amplifier as determined by various analyses, describe the present status of the performance of ring cathodes designed for inductive output amplifiers, i.e., the narrow-band, cavity-based klystrode under development at Varian/CPI and the wide-band, helix-based twystrode under development at NRL, and identify the challenges that remain before this new rf source technology is realized. [S0734-211X(98)02702-4].
The paper presents the achievements in research and development of the compact optical CCD based guiding system. The ultimate goal of the project is a modest size, low mass and rugged system to be applied for subarcse...
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ISBN:
(纸本)081942742X
The paper presents the achievements in research and development of the compact optical CCD based guiding system. The ultimate goal of the project is a modest size, low mass and rugged system to be applied for subarcsecond optical Ground-Space guiding and tracking. The system includes the optics, the CCD sensor with the readout and an image-processing algorithm. The optics consists of a diffraction limited objective, four-element lens system with the effective input aperture 90 millimeters. The objective focal length 300 mm is extended by the additional relay optics. The resulting effective focal length is 3000 millimeters, the focal spot size is 65 micrometers Airy disc diameter. The combination of the diffraction limited objective design, focal extender and mechanical construction permitted to keep the overall length bellow 600 millimeters and the total mass bellow 5 kilograms while maintaining high ruggedness at one are-second level. A sensor, the Texas Instrument CCD chip 192x164 pixels, 15 micrometers size is used. The custom designed readout and data processing hardware has been developed. Parallel communication maintains image download time 0.6 second with 12 bits amplitude resolution. The data acquisition and image processing software package running under MS Windows 95 or NT provide all functions for the camera control, data acquisition and image processing for precise target position evaluation. The position is evaluated as the centre of mass of square neighbourhood of the brightest CCD pixel. Indoor test of the ultimate position resolution using different diffraction limited images and sizes are described. The image position resolution +/- 0.03 pixel has been achieved. It corresponds to 0.03 are seconds of angular resolution of the entire guiding sensor.
High brightness, high average power, diode pumped Nd:YAG solidstate lasers (DPSSL) are being developed by TRW as part of the Precision Laser Machining Technology Reinvestment Program. The use of diode pump arrays in ...
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ISBN:
(纸本)081942790X
High brightness, high average power, diode pumped Nd:YAG solidstate lasers (DPSSL) are being developed by TRW as part of the Precision Laser Machining Technology Reinvestment Program. The use of diode pump arrays in place of flashlamps, and zig-zag slab geometry, allow lasers to be scaled to power beyond the current generation of lamp-pumped rod lasers while providing excellent beam quality. The efficiency is 3 - 4 times better using diode arrays in place of flashlamps resulting in less waste heat in the laser medium and reduced optical aberrations. The corresponding beam quality provides more than an order of magnitude increase in the average intensity available at the workpiece, thus enabling new machining capabilities.
The development of superconducting tunnel junction detector arrays has now reached a stage where practical applications in X-ray astrophysics can be considered. The arrays are based on tantalum devices, with operating...
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ISBN:
(纸本)0819429007
The development of superconducting tunnel junction detector arrays has now reached a stage where practical applications in X-ray astrophysics can be considered. The arrays are based on tantalum devices, with operating temperatures of about 0.4 K. The energy resolution of these detectors is limited by Fano and tunnel noise to about 3 eV at 1 keV. The first results from a 6x6, tantalum based array are presented. These medium sized arrays have good energy resolution (2.5 and 6.8 eV at 270 and 1000 eV respectively) and adequate absorption efficiency (of order 80% and 30% at 500 and 1000 eV respectively). The possibility to operate and read out simultaneously more than one channel has been demonstrated. The uniformity of the array elements both in charge output and energy resolution is good, with the overall responsivity across the array varying by less than 5%. The energy resolution at X-ray energies is dominated by spatial non-uniformities in the individual pixel response. Such a performance allows us now to consider the development of a X-ray cryogenic camera based on STJ detectors. Provided the field coverage of these cameras can be extended through the development of larger format detector arrays, they have the potential to form a major basis for astrophysics instrumentation in the next century.
The development of an optical camera based on superconducting tunnel junctions has now reached a stage where practical applications in optical or UV astronomy can be considered. A prototype cryogenic camera (named S-C...
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ISBN:
(纸本)0819428906
The development of an optical camera based on superconducting tunnel junctions has now reached a stage where practical applications in optical or UV astronomy can be considered. A prototype cryogenic camera (named S-Cam) has been developed, based on a high quantum efficiency 6x6 detector array of tantalum Josephson junctions, and operating at a temperature of about 0.4 K. This paper describes the general characteristics of the camera, sensitive in the waveband from 350 to 700 nm and designed to be installed in 1998 at the Nasmyth focus of the William Herschel Telescope in La Palma, Spain. In addition to the performance of the overall system, the preliminary detector unit test results will also be presented. The present S-Cam system performance is discussed in view of future versions of the camera. Provided the field coverage of these cameras can be extended through the development of larger format detector arrays and adequate read-out electronics, they have the potential to provide a significant additional tool for optical and UV astronomy in the next century.
A capacitive fingerprint sensor array with pixel-parallel cellular logic in CMOS is presented. The system acquires a binary fingerprint image and performs several image processing algorithms, including thinning the ri...
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A capacitive fingerprint sensor array with pixel-parallel cellular logic in CMOS is presented. The system acquires a binary fingerprint image and performs several image processing algorithms, including thinning the ridges of the fingerprint structure and extracting its characteristic features. The massive parallelism of the architecture leads to a very low power dissipation. Results of both simulations and measurements on a demonstrator chip are shown. The approach is well suited for person identification applications, especially in small portable systems, such as smart cards.
This article introduces MEMS development in the Institute of Microelectronic at Tsinghua University. Several MEMS devices: smart sensors, micromotors, micropump and microphone are described.
This article introduces MEMS development in the Institute of Microelectronic at Tsinghua University. Several MEMS devices: smart sensors, micromotors, micropump and microphone are described.
development of light emitting diodes (LEDs) and arrays of diodes to be utilized in a modern and highly sensitive spectrophotometer is presented. The In1-xGaxAs1-yPy quaternary alloy semiconductor has been utilized in ...
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development of light emitting diodes (LEDs) and arrays of diodes to be utilized in a modern and highly sensitive spectrophotometer is presented. The In1-xGaxAs1-yPy quaternary alloy semiconductor has been utilized in the design and fabrication of surface emitting infrared LEDs in the spectral range from 1100 to 1650 nm. Custom made chips provide the surface-emitting LEDs with high radiance and superior far-field patterns. The hybrid 31-element array of LEDs was fabricated. A temperature sensor and a photodiode was incorporated on the hybrid circuit to control the temperature and light intensity of the diodes. The instrument prototype has been fabricated and preliminary experimental data have been collected.
A CMOS charge sensitive readout chain for pixel applications, has been designed and fabricated in 0.8 µm technology. The system is capable of simultaneous position sensing and energy measurement. Each pixel circu...
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A CMOS charge sensitive readout chain for pixel applications, has been designed and fabricated in 0.8 µm technology. The system is capable of simultaneous position sensing and energy measurement. Each pixel circuitry incorporates both analog and digital features to perform the dual tasks. The overall gain of the chain is 340 mV/fC. With an ENC of 61 e and a power consumption of 1.8 mW per pixel at 3.3V it is a promising solution for pixel X-ray detectors. The paper describes the system architecture and reports experimental measurements.
The paper describes the development activity of a mobile instrumentation devoted to city air quality monitoring. In particular the methods adopted for collecting and analysing the air samples, the preliminary processi...
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The paper describes the development activity of a mobile instrumentation devoted to city air quality monitoring. In particular the methods adopted for collecting and analysing the air samples, the preliminary processing of the raw data coming from a solidstatesensors array and the developed dynamic on field calibration procedure are discussed and the preliminary results obtained also are reported.
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