摘要:

Two successful methods are reported for achromatizing the white‐light reconstruction of a 2‐beam surface hologram. One method uses prisms for dispersion compensation. The other uses a single‐plane diffraction grating as the correcting element.

ISSN:0003-6951    

DOI:10.1063/1.1754635

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

Helium‐neon CW laser oscillations at 1.1523 &mgr; have been observed in a high‐velocity gas flow system utilizing the rapid mixing of metastable helium atoms with initially unexcited neon.

ISSN:0003-6951    

DOI:10.1063/1.1754636

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

Electron beam excitation of CdS crystals grown in an atmosphere of excess Cd has resulted in laser emission near 4900 A˚ with 350 W of peak output power and 26.5% overall (35% internal) power efficiency at temperatures as high as 110°K. Laser action was observed, although at considerably reduced levels of power and efficiency, at temperatures up to 250°K. The high performance of the lasers appears to be due to increased crystal uniformity and to the introduction or enhancement of highly efficient radiative transitions, both of which result from the Cd‐rich growth conditions.

ISSN:0003-6951    

DOI:10.1063/1.1754637

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

A transition from a moving striation to a helical oscillation was observed in the positive column of a helium discharge at a pressure of 0.4 mm Hg as an applied longitudinal magnetic field was increased. The frequency and amplitude of the moving striation decreased with increasing magnetic field. When the magnetic field reached a critical value of about 1650 G, a helical oscillation appeared and the two waves were observed to coexist. The striation disappeared with a further increase of the field, but the helical oscillation continued to exist.

ISSN:0003-6951    

DOI:10.1063/1.1754638

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

This Letter reports on a novel way of imaging, in amplitude and phase, the cross section of a sound beam. Because of the phase retention, any arbitrary cross section can be brought into focus by optical manipulation without changing the relative position of light beam and sound beam. The process is explained in terms of ray optics and various pertinent features are illustrated. Following a discussion about resolution, the experimental setup is described. Results show photographs of a 22‐MHz sound field behind various objects placed in the sound beam. In conclusion, the application to sound microscopy at higher sound frequencies is pointed out.

ISSN:0003-6951    

DOI:10.1063/1.1754639

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

Infrared laser emission at a number of wavelengths between 9.4 &mgr; and 13.7 &mgr; has been obtained from diodes of Pb1−ySnySe and Pb1−xSnxTe at 12°K and 77°K. Diodes were fabricated from vapor‐grown Pb1−ySnySe and both vapor‐grown and Bridgman‐grown Pb1−xSnxTe. Emission data indicate that, as in Pb1−xSnxTe, the energy gap in Pb1−ySnySe decreases with increasing Sn concentration, becoming zero at 12°K for some value ofywithin the range 0.11 ≤y≤ 0.14.

ISSN:0003-6951    

DOI:10.1063/1.1754640

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

Experimental evidence is presented to show that the domain walls in a thin film of permalloy may be used to influence the transition of a thin indium film as it goes from the superconducting to normal state. The magnetic field of the domain walls in the permalloy film drives the superconducting indium toward a normal state and the superconducting indium film tends to lock the domain walls of the permalloy into a permanent position.

ISSN:0003-6951    

DOI:10.1063/1.1754641

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

When infrared radiation is reflected from the surface of a degenerate semiconductor, a minimum is obtained in the reflection spectrum. This plasma minimum is related to the free carrier concentration, effective mass, and dielectric constant of the semiconductor. In a diffused semiconductor with high surface concentration, the absorption constant is high and consequently the reflected plasma minimum is directly related to the surface concentration of free carriers. By calibrating the plasma minima vs known impurity concentrations, it is possible to determine surface concentration inn‐ andp‐type silicon ranging from 5 × 1018to 5 × 1020cm−3using an infrared spectrometer with a wavelength span of 2.5 to 25 &mgr;.

ISSN:0003-6951    

DOI:10.1063/1.1754642

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

We measured the noise spectrum between 10 kHz and 10 MHz. In the region whereI∝V2, we found a noise suppression factor of 1/2 for the white noise, i.e.,I2= (1/2)4kT(∂V/∂I)−1&Dgr;f.

ISSN:0003-6951    

DOI:10.1063/1.1754643

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

The use of birefringent acoustic media in microwave—shear‐wave polarization transformers is described. Restrictions on the properties of the acoustic medium are discussed as well as the limitations imposed by the use of imperfect bonds between the transformer section and a delay medium. The principles are illustrated by application to a double‐ended variable delay line.

ISSN:0003-6951    

DOI:10.1063/1.1754644

出版商:AIP    

年代:1966

数据来源: AIP