摘要:

When a polished surface of a single crystal is examined with a converging acoustic beam the reflected signal has a characteristic response that is dependent upon the elastic properties of the reflecting surface. This property can be used in the acoustic microscope to monitor the thickness of layers deposited on these surfaces and the small‐scale variations of the elastic parameters in these materials.

ISSN:0003-6951    

DOI:10.1063/1.89551

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

We have measured the spatial frequency response of an experimental scanning acoustic microscope (SAM) at 375 MHz, using an acoustic high‐resolution reflection test target consisting of Au bars on a silicon substrate. Although the instrument resolves 1.6‐&mgr;m line detail quite well, in favorable agreement with theoretical predictions, the shape of the spatial frequency response curve differs substantially from expectations.

ISSN:0003-6951    

DOI:10.1063/1.89552

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

Glow formation and glow‐to‐arc transition processes of moderate‐volume atmospheric‐pressure discharge in a CO2laser gas mixture with and without external ultraviolet volume preionization are studied optically by an image‐converter‐intensifier camera. Three typical types of photographs for (i) glow and arc formation with preionization, (ii) glow formation only with preionization, and (iii) glow and arc formation without forming network. Discharge development is compared, and dominant factors to suppress arc formation of relevance to designing CO2TEA lasers are discussed.

ISSN:0003-6951    

DOI:10.1063/1.89553

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

The plasmaZ‐pinch behavior has been observed in a relatively small‐bore diameter tube and low bank voltage discharge system. The instant of the occurrence of the laser line at 4880 A˚ coincides with the plasma pinch time calculated by using a one‐fluid snow‐plow model. A determination of plasma pinch parameters by measuring the intrinsic stimulated emission of the ions is described.

ISSN:0003-6951    

DOI:10.1063/1.89554

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

The apparent complexity of the laser‐plasma coupling in laser fusion target irradiation has stimulated the need for carefully controlled experimental studies of the laser‐plasma interaction at the critical surface. A heliumZpinch has been constructed which produces a high density plasma, independent of the laser, enabling the separation of the laser‐plasma interaction physics from the plasma formation mechanism. Its peak electron density (4×1019cm−3), critical density scale length (70–200 &mgr;), and temperature (∼25 eV) make it suitable for simulating and studying laser‐pellet interaction mechanisms at CO2laser wavelengths. Detailed numerical modelling of these experiments was employed as a check against our diagnostics, as well as providing physical insight in those ranges of experimental parameters where measurements were not made.

ISSN:0003-6951    

DOI:10.1063/1.89555

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

Though LiNbO3and LiTaO3have excellent electro‐optic properties, they are insulators and therefore do not lend themselves for the realization of an efficient photodetector scheme. Using the idea of evanescent coupling we propose and demonstrate a convenient and efficient light detection scheme to be used with a variety of dielectric waveguide devices. The scheme utilizes an etched mesa photodiode fabricated in silicon, evanescently coupled to a waveguide for light detection. The high detection sensitivity (0.3 mA/mW at &lgr;=6328 A˚) and the possibility of incorporating integrated circuits on a common substrate (in Si or GaAs) make the scheme very attractive for hybrid integration of thin‐film optical and electronic devices.

ISSN:0003-6951    

DOI:10.1063/1.89556

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

Hall‐effect, conductivity, and solubility measurements were carried out on Cd‐diffused PbTe and Pb1−xSnxTe single crystals, doped under various Cd vapor partial pressures between 10−4and 10−1Torr. Most of the diffused Cd atoms are found to distribute uniformly as an electrically inactive impurity in the crystal lattice and only a small fraction act as active donors, most probably through metal vacancy sites. Saturation in electron concentration is observed at the high Cd partial pressures which can be related to the excess metal point‐defect concentration of the as‐grown cooled crystals.

ISSN:0003-6951    

DOI:10.1063/1.89557

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

The apparent discrepancy between theory and experiment in low‐velocity electronic stopping of heavy ions is shown to be resolved for several representative cases by taking into account the velocity dependence of both the effective charge of the ions and of the atomic stopping power for fixed ionic charge. A new formula for the electron density dependence of the stopping number is introduced, based on recent work by Vager and Gemmell.

ISSN:0003-6951    

DOI:10.1063/1.89548

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

In order to make a new alloy an electron emitter, several samples of Mo foils implanted with Ca+ions were prepared. The range distributions of Ca in Mo were investigated by the use of Auger electron spectroscopy (AES) combined with Ar ion sputtering. At the same time the correlation between the surface components and the photoelectric work functions of the sample was also investigated during the sputtering. In preliminary experiment the work function of Mo foil was decreased about 1 eV due to the implantation of Ca+ions to the amount of 1×1017ions/cm2.

ISSN:0003-6951    

DOI:10.1063/1.89549

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

The nonlinear optical coefficients of AlN have been determined as ‖d33‖= (23.2±35%)dQ11and ‖d31‖ ≲0.04‖d33‖ for thec‐plate film and for a fundamental beam at 1.064 &mgr;m. The result is discussed with reference to the bond‐charge model.

ISSN:0003-6951    

DOI:10.1063/1.89550

出版商:AIP    

年代:1977

数据来源: AIP