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Vol. 19, No. 11 (1963)

1963-06-05
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CONTENT
ON THE IMAGE QUALITY OF PLANE GRATING SPECTROMETER
WANG CHIH-CHIANG, SUI MIN-CHIO
1963, 92 (11): 705-716. doi: 10.7498/aps.19.705
Abstract +
In this paper various factors influencing the image quality of plane grating spectrometer are discussed in detail. By means of vector elgebra a general formula is given for the form of the spectral lines in relation to the form of the entrance slit. A formula describing the angular dispersion of the spectral line resulting from a circular slit is also given. Investigation on the optical performance of the Ebert-Fastie grating spectrometer shows that among various residual optical aberrations, due to unsymmetrical disposition of the incident and diffracting beams with respect to the grating surface, coma is the most serious image defect. This can however be corrected by changing the focal length of one of its reflecting mirrors and placing it at a definite distance from the other mirror. It is also shown that residual aberrations can be well eliminated by placing an aspherical correcting plate near the grating surface. By the latter means there is the potentiality of greatly improving the performance of the instrument; either the volume of the instrument may be greatly reduced where shorter focal length optical systems can be used, or much better light gathering capacity can be achieved without sacrificing its monochrometicity when the spectrometer is used as a monochrometor.
MAGNETIC TORQUE STUDIES OF THE ANISOTROPY OF A GRAIN ORIENTED NICKEL-IRON ALLOY
HO KAI-YUAN, WU PAO-CHING
1963, 92 (11): 717-726. doi: 10.7498/aps.19.717
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The magnetic anisotropy of a 50% Ni-50% Fe alloy, after (1) cold reduction and (2) cold reduction and annealing at various temperatures, has been determined from magnetic torque curves, from which the types of the rolling and recrystallization textures in the specimens have been deduced. In the specimens with perfect cube texture, the magnetic anisotropy constant k1 has been determined; the result is consistent with that of other authors' using single crystal specimens. The k1 value in the cold rolled specimens is, however, larger. The factors which may possibly influence the determined k1 values are considered; the influences due to the degree of ordering and the elastic energy induced by anisotropic magnetostriction are finally discussed.
ON THE INTENSITY OF MUTUALLY-INDUCED X-RAY FLUORESCENCE BETWEEN ELEMENTS
CHEN CHI, LI HUA-LIN, DIN JIA-YEN
1963, 92 (11): 727-734. doi: 10.7498/aps.19.727
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A formula is derived for the intensity of mutually-induced X-ray fluorescence between elements, and is found to be in agreement with experiment.
LOW CONTRAST RESOLVING POWER AND ABERRATION TOLERANCE OF OPTICAL SYSTEMS
WANG CHIH-CHIANG
1963, 92 (11): 741-752. doi: 10.7498/aps.19.741
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The assignment of aberration tolerances for optical systems suffering from wave-front aberrations greater than λ/4 is worth further studying. In this paper it is shown that "low" contrast resolving power of optical systems can be taken as an appropriate criterion for assessing image quality, where the optical transfer function can be evaluated approximately in terms of the sums of Legendre polynomials. Accordingly, the best program of aberration correction and tolerences in the case where certain aberration constants are inevitably present and others are adjustable in optical design can be obtained. The results so obtained as applied to aberrations of small magnitude comparable to λ/4 conform well to the Strehl Deffinitionshelligkeit method.
LOCALIZED MODES OF SPIN WAVES IN THE CUBIC FERROMAGNETICS
LI YIN-YUAN, ZHU YAN-QING
1963, 92 (11): 753-763. doi: 10.7498/aps.19.753
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In this paper, calculation has been carried out for the localized modes of spin waves around a magnetic impurity atom in a ferromagnetic of the simple cubic structure. There are three symmetry types, i.e., the s-type, the p-type and the dr-type mode. The wave functions and the curves of the energy levels against the parameter J′S′/JS of these modes are obtained. Next, the types of localized modes which may possibly exist in ferromagnetics of the bcc or the fcc structure are discussed. It is pointed out that probably the s-type mode is the only one to be expected in actual specimens. With the criterion that the Curie point of the specimen should increase with the concentration of impurity, several alloys are suggested for the experimental observation of the localized modes of spin waves. Finally, a general analysis of the spin quantum number of the spin wave states leads to the conclusion that it is impossible to excite the scattered modes with k0≠0 as well as the localized modes by the electromagnetic radiation.
1963, 92 (11): 764-766. doi: 10.7498/aps.19.764
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1963, 92 (11): 767-770. doi: 10.7498/aps.19.767
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