摘要:

The sign change of dielectric anisotropy at the characteristic crossover frequency of a nematic mixture is utilized in twisted nematic liquid crystal displays for turn‐off (decay) time reduction. This can be obtained by either (a) a two‐frequency addressing or (b) a high‐frequency erasing scheme where the high frequency is above the crossover frequency. Data are presented on Eastman Kodak 11900 nematic mixture.

ISSN:0003-6951    

DOI:10.1063/1.1655256

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

Epitaxial growth of a semiconductor film from solid solution by dissolution and transport of an evaporated semiconductor layer through a metal film has been demonstrated. A Ge growth layer of 4800 Å has been obtained by heating the system bulk‐Ge/Al/evaporated‐Ge at 300 °C. Electrical measurements indicate that the layers are heavily dopedptype. A silicon growth of 2000 Å has been obtained by heating the system bulk‐Si/Pd/evaporated‐Si at 600 °C. Channeling measurements show that the Ge and Si layers are well ordered and epitaxial with the underlying substrate.

ISSN:0003-6951    

DOI:10.1063/1.1655265

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

With the homeotropic boundary condition, the field‐induced cholesteric‐to‐nematic texture transition can show a large hysteresis effect such that at the same field strength either the cholesteric or the nematic texture is stable.

ISSN:0003-6951    

DOI:10.1063/1.1655274

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

A surface wave convolver has been fabricated and tested with an interdigital structure which serves both as the output transducer for the convolution signal and as the biasing electrodes for bidirectional surface wave amplification of the two countertraveling input signals. The structure consists of a CdSe film on aY ZLiNbO3substrate with a delay path of 5 &mgr;sec. A convolution efficiency of −16 dB m has been obtained. Time reversal has been performed with the device.

ISSN:0003-6951    

DOI:10.1063/1.1655284

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

It is revealed that a high‐resistivity ZnO film highly oriented with thecaxis perpendicular to a metal substrate surface can be used as a low‐frequency piezoelectric transducer which generates and detects compressional strain or stress perpendicular to thecaxis, i.e., perpendicular to the film thickness through the piezoelectric tensor componente311ord311. For example, tuning‐bar filters and a flat tuning‐fork filter are successfully composed of ZnO films and Elinvar‐alloy substrates whose resonant outputs are obtained even at frequencies lower than 100 kHz, and a piezoelectric microphone is composed of a ZnO film and a Ti membrane substrate.

ISSN:0003-6951    

DOI:10.1063/1.1655257

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

This paper describes a numerical method by which we have computed the change in molecular orientation with time in liquid‐crystal twist cells when the applied field is changed. No small‐angle approximation is made but backflow is neglected for simplicity. The general features of the results are illustrated with computations using typical elastic and viscous constants in doped MBBA, without and with a cholesteric twist term.

ISSN:0003-6951    

DOI:10.1063/1.1655258

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

The effects of dust on 1.06‐&mgr;m laser‐induced air breakdown for 100‐nsec pulses are reported. The thresholds in clean air were measured as a function of spot size and were found to scale as &lgr;−2compared to the 10.6‐&mgr;m results. A single 50‐&mgr;m carbon particle present in the beam lowered the threshold to ≃5×109W/cm2—a factor of approximately 0.02 that of clean air. The fractional reduction in threshold due to dust particles was comparable to that reported for 10.6‐&mgr;m breakdown.

ISSN:0003-6951    

DOI:10.1063/1.1655259

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

Proximity‐imaging techniques are used to observe thermally stimulated field emission (TSFE) from single‐domain and multidomain single crystals of LiNbO3. Experimental results are reported and the mechanism responsible for this emission is discussed.

ISSN:0003-6951    

DOI:10.1063/1.1655260

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

An electrostatic vacuum triode is described in which it is possible to efficiently produce intense ion beams in the energy range around 100 keV for short times (∼50 nsec). In experiments to date, results have shown excellent agreement with predicted behavior. Equivalent proton currents of almost 500 A have been obtained at a peak energy in excess of 100 keV. The triode can easily be adapted to existing electron beam facilities.

ISSN:0003-6951    

DOI:10.1063/1.1655261

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

The comparisons between the electronic computer data and the experimental results of the characteristics of a three‐anode accelerating lens system for field emission scanning electron microscopy (FESEM) are described. Experimentally two characteristics were obtained. One of them is the relation between the accelerating voltages and the control voltages for the fixed working distance. The other is the variation of the current with the accelerating voltages. In comparison with the results of the electronic computer simulation, a close coincidence was found for the former case, but for the latter the experimental results are approximately half as large as those obtained theoretically.

ISSN:0003-6951    

DOI:10.1063/1.1655262

出版商:AIP    

年代:1974

数据来源: AIP