Silicon electron multiplication (SEM) camera tube

A low-light-level television camera tube has been realized, which incorporates a silicon electron multiplication (SEM) target. Image electrons liberated from the photocathode bombard the target, causing an electronic amplification of several thousand, as well as electronic charge storage. The SEM tube shows a limiting sensitivity at photocathode illumination on the order of 10^-5lx, and approaches the picture degradation problem due to quantum fluctuation. Further degradation of the picture is observed by addition of an image intensifier tube to the SEM tube, and also in the case of an X-ray image pickup using the SEM camera with phosphor screen. The SEM tube can scarcely be injured by the exposure to a strong light.     

彩色显像管早期失效的机理研究

介绍了几只彩色显像管早期失效的性能特征和对其失效原因的诊断过程。其间，我们先后采用了残气质谱分析、慢性漏气的快速无损检测以及氦质谱检漏等技术手段来寻找失效原因。文中，重点介绍了“慢漏快检”的原理及其检测结果；其后，从理论上分析了这类管子的早期失效机理并对相关问题进行了讨论。最后，总结出的一些对策在付诸实施后，已取得了良好的预防效果。彩色显像管的早期失效并非仅这一种原因，应该针对其性能特征来具体分析，本文只提供解决本类型早期失效管的一种方法，公供参考。     

线型离子阱不同缓冲气体对汞离子的冷却效果研究

缓冲气体冷却是将离子阱中的离子云冷却的最有效和实用的办法,但缓冲气体的种类和数量是汞离子微波频标实验的关键技术。通过在马修方程中引入阻力项的方法,研究了线型离子阱中氦气、氖气、氩气对囚禁的汞离子的冷却效果,得到在氩气中汞离子运动的衰减时间是最短的。还研究了为使钟跃迁（40.5 GHz）的频率移动最小,所需氦气的压强为10-5 Torr,氖气的压强为2.4×10-5 Torr。考虑到缓冲气体对汞离子的冷却效率和对气体压强的敏感性,氖气要比氦气、氩气更适合作缓冲气体。     

CORAD (color radar)

A new system is presented for displaying radar signal parameters in color using techniques based on the modern math application of Venn-Euler diagrams. These diagrams are portrayed on a standard color television picture tube. The observer can monitor several signal parameters simultaneously which are in the form of dynamic kaleidoscopic patterns. The system appears to be most applicable to resolving radar target "signatures."     

Superconducting instrument systems

Some recently developed superconducting instrument systems which are based upon the use of a highly reliable thin-film superconducting quantum interference device (SQUID) are discussed in detail. These SQUID's, which are shown to have a noise temperature of less than 2 × 10^-4K, are capable of measuring: 1) magnetic flux with a sensitivity of 10^-11Gċcm²rms/√Hz; 2) magnetic field with a sensitivity of 10^-11G rms/√Hz; 3) magnetic field gradient with a sensitivity of 10^-11(G/cm) rms/√Hz. We present construction details and performance data on systems capable of making the above measurements.     

Sensitivity measurement of a 10.6-µm parametric upconverter

The sensitivity of a parametric upconverter for the detection of 10.6-µm radiation was measured. 10.6-µm radiation was mixed with the 1.06 µm beam of an Nd :YAG laser in properly oriented single-crystal proustite. The upconverted output at 0.967 µm was then detected by an S-1 photomultiplier tube. NEP of 1.1×10^-9W . s^½was measured.     

Current transient spectroscopy: A high-sensitivity DLTS system

A deep-level transient spectrometer (DLTS) has been built that measures current transients, rather than the usual capacitance transients, in p-n junctions. The system was developed to optimize sensitivity for the study of low-concentration processing-induced defects. An analysis of its performance as a function of timing parameters is presented. A noise analysis of both capacitance and current transient measurement is presented, showing that neither method has an inherent sensitivity advantage, and that both should be capable of detection limits of about 10^-7to 10^-8of the shallow doping concentration. Noise measurements indicate that a detection limit of 10^-7times the doping has been obtained. Spectra of a processed p⁺-n diode with no intentional contamination show several defect levels in the 10^-5ND, or 10¹⁰cm^-3, range. Spectra of gold-doped p⁺-n diodes yield emission data in good agreement with accepted values.     

Water vapor penetration rate into enclosures with known air leak rates

The rate at which water vapor penetrates a faulty seal in a "hermetically sealed" device has been examined both experimentally and theoretically in this study. The experimental data were generated by studying the rate of moisture ingress into two types of packages; a TO-5 can and a ¼ × ¼ in ceramic flatpack. The TO-5 packages were fitted with capillary tubes of varying diameters with known air leak rates and represented the gross leak range (down to 10^-5atm . cm³/s) while the ¼ × ¼ in ceramic flatpacks were used to study the fine leak range (10^-6to 10^-8atm . cm³/s). Both type packages were fitted with miniature moisture sensors (surface conductivity type) and calibrated at known relative humidities prior to sealing. The finished test packages were then exposed to constant high-humidity conditions and monitored for moisture content as a function of time. A theoretical analysis was performed by using conventional leak rate equations to convert air leak rates, at standard test conditions, to water vapor leak rates at partial pressure differentials seen typically at room ambient conditions. These data compared favorably with the experimental results in the range tested and suggests that present hermeticity specifications are too lenient for long-term reliability requirements.     

Professional HDTV digital recorder

Some of the essential technology for record/playback systems in professional HDTV digital recorders is described. The full bandwidths of 1125/60 HDTV signals (30 MHz for luminance and 15 MHz each for the two color difference signals) were recorded. An 8-8 mapping channel code and integrated detection were used. A special phase locked loop (PLL) to cope with picture search functions was developed. At the high data rate of 148.5 Mb/s per channel and the high linear density of 0.345 μm per bit, the recorder operates with a word error rate of less than 10^-4      

Crosstalk degradation caused by optical amplification in amultichannel FSK heterodyne system

The crosstalk degradation caused by an optical amplifier in a four-channel FSK (frequency-shift-keyed) heterodyne communication system is measured. A bit error rate (BER) floor of 3×10^-4 is observed when the channels are spaced by 200 MHz, FSK modulation at 45 Mb/s, and when the optical input signal is large enough such that the gain is compressed by 2 dB relative to its small-signal value. The receiver is substantially improved by reducing the optical power amplifier input. However, the sensitivity increases only to a maximum value beyond which it degrades as the optical power of the demodulated channel becomes small relative to the noise of the optical amplifier. The combined effect of the crosstalk and the amplifier noise yields an optimum sensitivity of 250 photons/b for BER=10^-9. This result is 5 dB poorer than the sensitivity obtained in the absence of an optical amplifier     

用于红外探测器组件检测的超高灵敏度检漏仪

提出了一种采用累积法进行超高灵敏度氦质谱检漏的先进技术,基于该技术及相关材料特殊处理工艺设计并研制出了新型超高灵敏度检漏仪器,检测灵敏度优于8×10-15 atm.cc/s.He,是常规氦质谱检漏仪器灵敏度的1000倍以上,已成功应用于红外焦平面探测器组件等长寿命真空电子元器件产品的研制和生产工艺检测中,也是高能粒子加...     

On Ultra-Fine Leak Detection of Hermetic Wafer Level Packages

Theoretical and practical ranges of leak rates measurable by the helium mass spectrometer are characterized. The effect of noise due to: 1) background helium present in the spectrometer and 2) desorption of helium that attaches itself to the specimen surface during bombing is quantified experimentally. The results guide a framework to extract the true leak rate from the measured leak rate profile. An optical interferometry based hermeticity measurement technique for ultra-fine leaks is proposed. The setup to implement the technique is described and a preliminary experimental result is reported.     

PLL propagation delay-time influence on linewidth requirements ofoptical PSK homodyne detection

Phase-locked loop (PLL) propagation delay-time influence on optical homodyne detection was investigated both theoretically and experimentally. Applying the Pade approximation, which is often used in the control system, to the calculation of the phase-error variance with the nonzero loop delay time, a high-accuracy analytic expression phase-error variance is obtained. The linewidth requirement with the nonnegligible loop delay time for phase-shift-keying (PSK) homodyne detection is obtained as δν=2.04×10^-3/τ where δν (hertz) is beat linewidth and τ (seconds) is the loop delay time. The linewidth requirement with small delay time approaches δν=6.2×10^-4 R_b where R_b (bits-per-second) is the system bit rate. Results were confirmed by a 10-GB/s optical PSK homodyne detection experiment using external cavity laser diodes. Receiver sensitivity degradations due to loop delay time and beat linewidth are in good agreement with theoretical results     

Development of an Error-Correction Method for Data Packet Multiplexed with TV Signals

By using the vertical blanking period of television signals, it is possible to transmit coded data such as teletext, telesoftware, music, etc. However, the quality of data transmission on television transmission channels is very poor and a powerful error-correction code is required to reliably transmit coded data. From the results of simulations using error pattern data collected in field tests and the comparison of various error-correction codes under many conditions, it has been determined that the shortened (272, 190) majority-logic decodable difference-set cyclic code is a suitable code for NTSC TV signals. By using error-correction codes proposed to date for teletext, it has been difficult to obtain a page error rate (PER) of 10^-1in many measurement points. However, PER's of less than 10^-2can be obtained in this system, even when random noise, ghost interference, or waveform distortion are present and bit error rates (BER's) are 10^-2. This paper also gives an empirical equation according to the error data and shows that the error-correction capability increased equivalently up to 11 error-bits in a packet by modifying the decoding algorithm.     

Feasibility study on QPSK optical-heterodyne detection system

The feasibility of a QPSK (quadrature-phase-shift-keying) optical heterodyne detection system for a high-speed and long-span coherent transmission is investigated. The key factors, which are the modulation method and the spectral linewidth requirement for optical light sources, are discussed. Through theoretical analysis and the simulation experiment, it is confirmed that the required beat spectral linewidth for QPSK coherent detection is less than 7.5×10^-5×bit rate. It is also shown that the required spectral linewidth for QPSK differentially coherent detection is less than 2.5×10^-5×bit rate. These results show that the gigabits-per-second range QPSK optical heterodyne detection can be realized with conventional external cavity laser diodes     

氦原子高激发态的精确计算

以Rayleigh-Ritz变分法以及组态相互作用为理论基础,选取Hylleraas基为基元,计算了氦原子高激发态能级结构,精度达到10^-4以上。在低激发态时,计算结果与Drake的计算结果比较接近,在高$L$高激发态时,符合理论预期。此外,选取$L=10$激发态为样本,分析了氦原子在第十个激发态时能量收敛情况。通过分析,随着基组的扩大,能量收敛于一个固定数值,从而证明了计算结果的可靠性。最后,选取$L=10$激发态为样本,分析了氦原子处于高激发态时分波对应的关联度和能量贡献度。经过计算, (0, L) L组态贡献度最大,而其他分波的贡献则很小。因此,组态相互作用法可应用于氦原子的高激发态计算。     

Measurement of mode couplings and extinction ratios inpolarization-maintaining fibers

Polarization mode couplings in the axial direction are evaluated for polarization-maintaining fibers using optical heterodyne detection. To verify the validity of this approach for fibers with various coupling constants, the method is applied to three fibers with modal birefringence values of 3.0×10^-4, 1.1×10^-4 , and 1.5×10^-4, respectively. The coupling constants in the 1.7×10^-4 m^-1 to 6.4×10^-7 m^-1 range are evaluated with a length resolution of 1 m. The extinction ratios are obtained from the coupling constants averaged over the fiber lengths. These values are in good agreement with the values measured directly from power ratios between the orthogonally polarized modes     

Josephson junction millimeter microwave source and homodyne detector

A millimeter and submillimeter microwave source is described in which a point-contact Josephson junction is used as both the emitter and as a homodyne detector of the microwave radiation. The microwave radiation is conveyed from the Josephson junction to the room-temperature environment outside the Dewar of liquid helium by an oversize waveguide. A room-temperature Fabry-Perot resonator refocuses the radiation on the oversize waveguide which returns the radiation to the emitting junction which also serves as a coherent detector with sensitivity 10^-15W/√Hz. The detector is sufficiently sensitive that the emitted power of 10^-12W can be detected with high signal-to-noise ratio. Power required by the junction is of the order 10^-6W from the bias supply. For the experiments reported, the wavelength of the emission could be varied over discrete wavelengths between 1.1 and 2.6 mm by varying the voltage bias across the junction. These wavelengths corresponded to the resonant frequencies of a cavity tightly coupled to the Josephson junction, and the frequencies can be changed by modifying the geometry of the cavity.     

Measurement of a very high displacement sensitivity of the beat frequency in an He-Ne laser

An He-Ne laser with enhanced sensitivity to small displacements is described. The laser is forced to oscillate in two longitudinal modes by an internal mode selector of the Fox-Smith interferometric type. Displacements are induced in one arm of the mode selector and cause a frequency modulation of the beat frequency between the two modes. Experimental data is presented which demonstrate that the frequency modulation varies quadratically with the displacements. This behavior is explained in terms of changes in the dispersive index of refraction of the amplifying medium, induced by the displacements. The laser beat frequency has a displacement sensitivity of4 times 10^{11}Hz/cm and a noise equivalent displacement of 10^-12cm/Hz^1/2. The system was used to measure displacements on the order of 10^-4Å.     

Annealing of linear birefringence in single-mode fiber coils:application to optical fiber current sensors

Annealing procedures that greatly reduce linear birefringence in single-mode fiber coils are described. These procedures have been successfully applied to coils ranging from 5 mm to 10 cm in diameter and up to 200 or more turns. They involve temperature cycles that last 3-4 days and reach maximum temperatures of about 850°C. The residual birefringence and induced loss, are minimized by proper selection of fiber. The primary application of these coils is optical fiber current sensors, where they yield small sensors that are more stable than those achieved by other techniques. A current sensor with a temperature stability of +8.4×10^-5/K over the range from -75 to +145°C has been demonstrated. This is approximately 20% greater than the temperature dependence of the Verdet constant. Packaging degrades the stability, but a packaged sensor coil with a temperature stability of about +1.6+10^-4/K over the range from -20 to +120°C has also been demonstrated