摘要:

The principle of operation of phase‐sensitive amplifiers is discussed. Three examples of the use of the phase‐sensitive amplifier, or ’’lock‐in,’’ are given. The examples have been chosen to be suitable for undergraduate laboratory use. The paper is concluded with the description of an inexpensive ’’student’’ lock‐in amplifier which has an overall voltage gain of 1000.

ISSN:0002-9505    

DOI:10.1119/1.9690

出版商:American Association of Physics Teachers    

年代:1975

数据来源: AIP

摘要:

The concepts of linear optics are applied to the physics of energy coupling into laser‐produced plasmas currently of interest in laser‐initiated fusion research. The effects of polarization and angle of incidence upon reflection and refraction are recalled. Singular behavior occurs in the region of the plasma where the real part of the dielectric constant vanishes, the so‐called ’’critical density’’ region. The effective generation of Langmuir waves at the surfaces of bounded plasmas through the optical resonance of obliquely incident electromagnetic radiation is heuristically discussed. Enhanced electric fields, enhanced ’’collisionless’’ damping, harmonic generation, the presence of energetic electrons, and density profile modifications which result near the critical density from the excitation of these plasma waves are described. While more complex plasma processes may occur, they are not within the scope of this review.

ISSN:0002-9505    

DOI:10.1119/1.9691

出版商:American Association of Physics Teachers    

年代:1975

数据来源: AIP

摘要:

As a horizontally moving light source is approaching and passing over a wall, it is shown that the shadow on the ground at a nearer position to the wall may disappear at an earlier time. In fact, the light rays first illuminate a point on the ground and the neighboring shadow around this point will disappear subsequently in the shape of illuminated ellipses of increasing area. Such an extraordinary phenomenon occurs whenever u/c≳1−hW/hS, where c and u are the speeds of light and the source, and hWand hSare the heights of the wall and the source, respectively.

ISSN:0002-9505    

DOI:10.1119/1.9692

出版商:American Association of Physics Teachers    

年代:1975

数据来源: AIP

摘要:

A device is described that employs two diffraction gratings and three or four simple lenses to produce arbitrary absorption or emission spectra that may be Doppler shifted and spectroscopically examined by students some distance away. In this sense it may be regarded as a sort of artificial star whose spectrum may be compared with known spectral standards and qualitatively or quantitatively analyzed as an undergraduate laboratory exercise or simply shown as a demonstration.

ISSN:0002-9505    

DOI:10.1119/1.9693

出版商:American Association of Physics Teachers    

年代:1975

数据来源: AIP

摘要:

The classical interpretation of the spin echo is reviewed, followed by a simple quantum‐mechanical derivation of the general echo phenomenon for a two‐state system. The photon echo is then examined, and graphs of hydrogenic wave functions for eigenstates and transitional states are shown as examples. As many as possible of the classical notions associated with the spin echo are applied to the case of photon echoes.

ISSN:0002-9505    

DOI:10.1119/1.9694

出版商:American Association of Physics Teachers    

年代:1975

数据来源: AIP

ISSN:0002-9505    

DOI:10.1119/1.9695

出版商:American Association of Physics Teachers    

年代:1975

数据来源: AIP

ISSN:0002-9505    

DOI:10.1119/1.9697

出版商:American Association of Physics Teachers    

年代:1975

数据来源: AIP

ISSN:0002-9505    

DOI:10.1119/1.9698

出版商:American Association of Physics Teachers    

年代:1975

数据来源: AIP

ISSN:0002-9505    

DOI:10.1119/1.9699

出版商:American Association of Physics Teachers    

年代:1975

数据来源: AIP

ISSN:0002-9505    

DOI:10.1119/1.9711

出版商:American Association of Physics Teachers    

年代:1975

数据来源: AIP