摘要:

A simple interferometric technique which uses a diverging spherical comparison wave for study of laser beams is described. The interference pattern resulting from superposition of the primary beam and a small portion of the expanded comparison wavefront provides information about both the phase and some spatial coherence properties of the primary radiation. Expected interference patterns have been obtained for a spatially coherent beam from a He&sngbnd;Ne gas laser. The phase character and spatial coherence features of the beam from aQ‐switched ruby laser have been investigated.

ISSN:0003-6951    

DOI:10.1063/1.1754820

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

Excited20Ne at 0.1 torr was placed inside the cavity of a single‐frequency, 6328‐Å laser. A pronounced peak appeared in the output power, caused by an inverted Lamb dip effect. Because of the low pressure used, this peak was only 30 ± 5 MHz wide and must be very near the atomic resonant frequency. In contrast, the overall output curve was blue‐shifted 60 ± 10 MHz by the 3 torr nominal pressure in the laser gain tube. This saturated absorption effect can be used as an absolute reference for the frequency stabilization of He&sngbnd;Ne and similar lasers.

ISSN:0003-6951    

DOI:10.1063/1.1754821

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

The effect of adsorbed oxygen on the photoelectron yield of bulk polycrystalline tungsten was studied at photon energies of 7.7, 10.2, 11.8, 16.9, and 21.2 eV. Use of ultrahigh vacua ∼3 × 10−10torr ensured sample cleanliness prior to oxygen exposure. The photoelectron yield decreases with oxygen exposure because of the increase in the electronic work function of the tungsten photocathode. However, athv= 21.2 eV, an increase in photoelectron yield with oxygen exposure also appears and is believed to be due to photoelectron emission from the adsorbed oxygen atoms.

ISSN:0003-6951    

DOI:10.1063/1.1754822

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

It is shown that the h.f. conductancegof a double‐injection Ge diode shows transit time effects and that the limiting noise can be represented by a current generator (4kTg&Dgr;f)1/2in parallel to the device. In contrast, the single‐injection diode seems to be best represented by a current generator (8kTg&Dgr;f)1/2.

ISSN:0003-6951    

DOI:10.1063/1.1754823

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

Signal gain has been measured directly in a LiNbO3near‐infrared parametric amplifier. A maximum gain of 30% was achieved at a signal wavelength of 1.152 &mgr; using 50 kW of pump power at 0.53 &mgr;. Theoretical and experimental gain coefficients are given and compared with the results of recent parametric oscillator experiments by other workers.

ISSN:0003-6951    

DOI:10.1063/1.1754824

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

Results are given of measuring the phase velocity of elastic surface waves in the three principal planes of &agr;‐quartz. The observation of a leaky surface wave is reported.

ISSN:0003-6951    

DOI:10.1063/1.1754825

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

We have observed negative resistance behavior in evaporated silicon films at room temperature and at liquid nitrogen temperatures which we believe is due to double injection. This, to our knowledge, is the first reporting of double injection in silicon thin films, as well as the first reporting of an active device prepared from silicon thin films. Sample lengths in previous work have ranged from one hundred to several thousand microns. The films used in our work are 0.4 to 0.6 &mgr; thick.

ISSN:0003-6951    

DOI:10.1063/1.1754826

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

Photocurrent measurements on single‐crystal semi‐insulating CdS at 4.2°K show that the photocurrent does not undergo multiplication by impact ionization even though the dark current does.

ISSN:0003-6951    

DOI:10.1063/1.1754827

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

An empirical formula has been found connecting the pressure and temperature dependence of the shear strength of crystalline solids. It contains only two adjustable parameters and has been found to be valid for a variety of materials. The formula should prove useful for calculating the shear strength of materials under pressure and/or temperature conditions where direct measurements are inconvenient or impossible.

ISSN:0003-6951    

DOI:10.1063/1.1754828

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

Ferroelectric domains in single‐crystal tetragonal barium titanate have been observed in the scanning electron microscope. Contrast in the image results primarily from the surface topography associated with domains; thus it is possible to observe surface structure associated with 90° domains under high magnification. In the scanning microscope one can observe the disappearance of domain structure above the Curie temperature, as well as domain growth and movement produced by intense electron bombardment. Scanning electron micrographs of as‐grown BaTiO2have revealed surface structure which may correspond to the permanent surface layer which exists on BaTiO3.

ISSN:0003-6951    

DOI:10.1063/1.1754829

出版商:AIP    

年代:1967

数据来源: AIP