In this paper a study is made of the annular aperture with primary spherical aberration and defocussing using the Zernike polynomials. Both the intensity distribution in the central plane (p=0) and the axial intensity (q=0) have been evaluated for a large number of cases. A modification of the annular aperture, the annulus aperture, has also been investigated.
Sensitivity and spectroscopic characteristics of a photoconductive detector using InSb single crystals are studied. Noise equivalent power (NEP) of an n type detector, its carrier concentration being 3.6×1012cm-3 at liquid nitrogen temperature, was 7×10-11 watts when exposed to radiation from 500°C blackbody. On the other hand, the NEP of a p type detector, its carrier concentration being 3.5×1013cm-3 at same temperature, was 3×10-11 watts. Spectroscopic sensitivity of a detector with high purity elements is found to have a large and wide peak near the wave length 5μ, for the surface of the detector elements is less sensitive than its bulk. This implies that the life time of surface excitation is shorter than that of volume excitation. Threshold wave length of n type detectors is longer than that of p type detectors, the wave lengths being 6μ and 5.75μ respectively.
Phase lag of light wave by reflection on Ag thin films is measured from the shift of interference fringes. The results agree with those calculated theoretically. Phase lag of thin films thinner than 300 Å differs from that of bulk metal and the calculated maximum phase difference of 0.41 rad. occurs when the film thickness is 40Å.
In a previous paper1), a generalization of the Maggi-Rubinowicz theory was developed. The Kirchhoff diffraction integral was expressed as the combined effect of a boundary diffraction wave (represented by a line integral along the boundary of the aperture) and of waves originating in certain special points inside the aperture (singularities of an associated new vector potential). In this paper a general expression for the vector potential W (r', r) associated with any mono chromatic wave field U(r)e-iωt is deduced. In terms of W, the integrand vector V(r', r) of the Helmholtz-Kirchhoff integral can be expressed in the form V(r', r)=curl' W(r', r). It is shown that W(r', r)_??_×_??_eiκτgradU(r+τ8)dτ+W∞, where s=r'-r, _??_=s/s, k=ω/c and W∞ denotes a certain residual contribution from infinity. This general formula is applied to the case of a spherical wave (created by Maggi and Rubinowicz in a different manner) and the contributions of the singular points of W are examined.
In part I of this investigation††, a general expression was derived for a new vector potential W(r', r) associated with a monochromatic wave field U(r)e-iωt. In the present paper the general time dependent wave field U(r, t) is considered which satisfies the homogeneons wave equation. According to the general form of the Kirchhoff theorem, the wave field at a typical point P(r) can be expressed as an integral taken over a surface surrounding P by means of a formula of the form, U(r, t)=∫∫V(r', r, t). nds It is shown that the integrand vector V may be derived from a time dependent vector potential W(r', r; t) by means of the relation V(r', r; t)=curl' W(r', r; t), where W(r', r;t)=1/4πs_??_×_??_[grad U(r+τ_??_, t')]dτ+W∞t'=t-τ/c (s=r'-r, _??_=s/s), W∞ being a certain residual contribution from infinity. This formula is used to derive expressions for the vector potential of a general plane wave and a general spherical wave.
By the use of theoretical results of study on mounting presented previously by one of authors in which a concave grating is rotated about a suitable point to change the wavelength with fixed direction of the emerging ray, numerical calculations are performed by electronic computer to find usable mountings. It is shown that Eagle mounting gives the minimun radius of rotation. In this case, the entrance and exit slits are required to be displaced upwards and downwards over the Rowland circle plane respectively. Therefore the effect of displaced slits is studied. In a general mounting, conditions of image-forming of a long slit are investigated and it is found that if the slits are made in the form of definite hyperbolic curves, all terms up to the 3rd order in light path function can be made equal to zero except the one of wl2.
Decay and build-up of luminescence of ZnS: Cu, Cl are studied on five samples each of cubic and hexagonal crystal structures activated with copper varying in amount from 0 to 0.1 weight per cent. The measurement of decay and build-up characteristics of the samples is made at 5320, 4950, and 4610 Å in emission spectra with a synchroscope. Emission spectra of phosphorescence during decay are also measured with a rotating cylinder coated with the phosphor and wite a spectrophotometer. With the samples containing copper activator of 0.0001_??_0.01 weight per cent, which show both of blue and green emission bands, the decay and rise time of blue band have the tendency to decrease as the copper content increases, while those of the green band remain unchanged. The phenomena that the two bands decay in parallel, which was suggested by Fok, could not be observed in the present experiment. The emission peak of samples activated with copper of 0.1 weight per cent shifts to longer wavelengths during decay and build-up.
A shearing interferometer by the use of polarized light is devised for the measurement of generalized transfer functions of microscope objective, the object plane of which is illuminated through a condenser. The relative shear between two interfering wave-fronts is obtained by a birefringent system, which is located at the focus of a converging wave-front and is made movable normally to the optic axis. The birefringent system consists of a piano-convex lens and a piano-concave one of calcite cut parallel to the optic axis and cemented together with their axis crossing at right angle. This system can easily be applied to the autocollimation method and is capable of obtaining a sufficient amount of light without reducing the visibility of interference fringes over the whole range of shear. These are the conditions indispensable for measuring the transfer function of microscope objectives which have a small amount of residual aberrations and therefore have a tolerable value of response for all the spatial frequencies corresponding to the entire range of shear. Experiments were carried out on low power microscope objectives with primary spherical aberrations of 0.0, 0.5 and 1.0λ. Experimental results show fairly good agreement with calculated
Persistent internal polarization of ZnS and ZnCdS phosphors is investigated. Polarization P is found to be expressed by an exponential function of illumination intensity I and polarization time t as P=P∞ [1-exp(-βIt)] Polarization P∞, after a long polarization time is determined by the applied voltage alone, and β is a constant depending on the phosphor materials and the cell structures. This leads to a conclusion that such an exponential characteristic is due to the decrease in effective internal field with the formation of polarization and not caused by all the trape being filled up. On the basis of the experimental results, the polarization effect is applied to an electric static photography. On the authors' phosphor sheets, excellent latent images were obtained which were made visible by charged particles applied on them. Illumination intensity of 40lx, polarization time of 5 seconds and applied voltage of 600 volts per 70 microns were used for this attempt.
Methods of determining the location of the optimum center of rotation for constant-deviation dispersing prisms such as represented by the Pellin-Broca's prism, as well as for constant-deviation prism systems arranged according to Wadsworth, are described. By rotating the prism or the prism system around this axis, practically no lateral shifting of the central point of either the entrance or the exit aperture of the system occurs, so that the full aperture of the system can be utilized irrespective of the wavelength of light selected by the system. The optimum center of rotation of the first kind, so may be said, proposed by Forsythe for the Pellin-Borca's prism with 90° deviation angle, and that proposed by Wadsworth for his own mounting, are useful only in a special case when the aperture of the collimator lens or the collector lens is, or both are, definitely smaller than the aperture of the prism. And in almost every case when the apertures of the lenses and the prism have matched dimensions, the optimum center of rotation of the second kind, proposed by the author, affords better utilization of the system. In the case of the “direct-vision” Wadsworth mounting, the center of rotation of the second kind exists, only when the separation d between the plane of the mirror and the base plane of the prism fulfills the following condition _??_ where A is the vertex angle, b the length of the refracting side plane of the prism, and i the angle of incidence of the light adopted to determine the “basic configuration” of the system. The centers of rotation of both the first and the second kind coincide in this case.