摘要:

We describe a new twisted nematic liquid crystal display effect exhibiting bistable equilibrium states under an applied field. Each state is characterized by a boundary layer configuration whose properties provide for optical differentiation of the states. The basic principles, optics, and switching properties of this device are discussed.

ISSN:0003-6951    

DOI:10.1063/1.92989

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

A recently developed method for precise phase measurement of vhf/uhf signals has been used in frequency measurement system. Results are given from three test cases, two broadband (10 and 20 MHz) and one narrowband (300 kHz). In each case the frequency was measured with a precision which was a small fraction of the bandwidth and in the best case was 0.07% of the bandwidth. The configuration tested produced a reading every six milliseconds but a much higher rate is possible.

ISSN:0003-6951    

DOI:10.1063/1.92990

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

A relationship is derived between photoacoustic signals from localized sources and temperature distributions from extended sources. The result is applied to simple geometries.

ISSN:0003-6951    

DOI:10.1063/1.92991

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

We have developed a new noncontact optoacoustic method for simultaneous measurement of flow velocity and temperature in a flowing fluid to accuracies of 5 cm/s and 0.1 °C, respectively. It is applicable for pure particulate‐free gases and liquids. A pulsed ND‐doped yttrium aluminum garnet (YAG) laser of 40‐mJ energy and 10‐ns duration generates an acoustic pulse whose propagations in directions along and against the flow are monitored by a total of three cw probe beams. We also describe the minimization of errors due to a blast wave (which propagates faster than sound) being generated at the source.

ISSN:0003-6951    

DOI:10.1063/1.92992

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

An exact solution of the two‐dimensional free‐space Poisson equation for a discharge geometry is derived. It allows the calculation of electrode profiles starting from any assumed field distribution in the discharge midplane. Analytic expressions are obtained for a new class of profiles, and their properties are illustrated with the example of an XeCl laser discharge. The new profiles provide excellent field uniformity, and they are much more compact than other analytical profiles such as those of Rogowski and Chang.

ISSN:0003-6951    

DOI:10.1063/1.92993

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

Dislocation breakaway has been observed in CdS during plastic deformation under illumination. The magnitude and frequency of such breakaways are found to be strongly temperature dependent in the range from 0 to 70 °C. This observation suggests a way to distinguish among several theories of photoplasticity.

ISSN:0003-6951    

DOI:10.1063/1.92994

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

Resistivity measurement on carbon black‐polyvinylchloride (PVC) composites combined with Monte Carlo calculations on the percolation threshold of a two‐dimensional system of oriented sticks has suggested that the carbon black aggregates in these compression molded composites are oriented. Although electron microscopy failed to disclose structure in the composite, polarized infrared transmittance measurements do provide direct evidence for the orientation of carbon black aggregates. The degree of orientation from optical polarization correlates with orientation suggested by the resistivity measurements.

ISSN:0003-6951    

DOI:10.1063/1.92995

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

The photoquenching effect of electroluminescence (EL) has been observed for the first time in thin‐film ZnS:TbF3EL devices. The luminescent intensity and the conductive charge are quenched, when the device is exposed to a visible light of energy between 1.75–2.75 eV. The maximum photoquenching rate of 45% is observed at a voltage slightly higher than the EL threshold voltage. The recovering time from the photoquenching is of the order of several seconds. This photoquenching effect is likely to be due to deep hole traps.

ISSN:0003-6951    

DOI:10.1063/1.92996

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

Thermally stimulated currents from positively corona‐charged polypropylene films which were heat treated at various temperatures have been studied in the temperature range 20–165 °C. Three peaks are observed in the TSC spectra. Intensities of these peaks strongly depend on the thermal history of the sample films. A thermal effect of the TSC, which has been introduced during vacuum deposition of metallic electrodes on the sample films, is demonstrated. Observed results suggest that the electrical trap properties in polypropylene depend on the fine structure of the polymer.

ISSN:0003-6951    

DOI:10.1063/1.92997

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

Large optical cavity buried heterostructure window lasers in which only the transparent AlGaAs waveguiding layers, and not the active layer, extend to the laser mirrors have been fabricated. These lasers have threshold currents and differential quantum efficiencies comparable to those of regular large optical cavity buried heterostructure lasers in which the active region extends to the laser mirrors, however the window lasers have been operated under pulsed conditions at three times the power at which otherwise identical lasers without windows degrade by catastrophic mirror damage.

ISSN:0003-6951    

DOI:10.1063/1.92984

出版商:AIP    

年代:1982

数据来源: AIP