Surface topography of YAKE, or stained areas, artificially produced on polished surfaces of optical glasses by dipping the glass samples into alkaline, acid or neutral solutions, is studied with the aid of a phase-contrast microscope and by interferometric techniques. One half of the surface under investigation is protected by covering with a layer of asphalt, and the other half exposed to the etchant. In the case of alkaline corrosion, the glass is uniformly dissolved into the solution, and the height of the exposed surface is diminished at a constant time rate. In F 2, KF 2, KF 6 and SF 3, a peculiar attack by the etchant is found in a zone under the asphalt layer just next to the boundary line between the protected and unprotected areas. A kind of groove due to the. intense corrosion is formed in this boundary zone in the case of F 2, KF 2 or KF 6. AOYAKE layers exhibiting interference colours are formed by acid corrosion in all kinds of glasses examined but LaK 13, which is dissolved into acid solutions. Just after the corrosion, the height of the AOYAKE surface is the same as that of the untreated (protected) surface, but the former is diminished by desiccation in vacuo or by heat treatment. The amount of this diminution in height of the corroded surface is not proportional to the duration of corrosion. The AOYAKE layers of SF 3 and SK 5 are cracked when the corrosion treatment is prolonged, and small fragments come off when dried. If the samples of F 2, KF 2, KF 6 and SF 3 attacked by acid are kept in a humid atmosphere, many microcrystals are seen to appear on the AOYAKE surface. A very soft AOYAKE layer is formed on the surface of LaK 13 by pure water corrosion. Again in this case, a peculiar attack is observed in a zone along the boundary line.
The growth of low refractive index layer (L. I. layer) on the surface of optical glass in alkali or water solution of SiO2 is studied in detail using a polarization spectrometer and by mulitiple beam interferometry. The glass samples used in this experiment are barium borosilicate glass (SK 16) and lead glass (SF 3). Results obtained are as follows: 1) Dissolution of the glasses is prevented by high concentration of SiO2 in alkali solution, and the growth of thick L. I. layer is observed on SK 16 as well as on SF 3. 2) A small quantity of SiO2 in neutral or water solution has considerable effect in producing L. 1. layer on the surface of barium borosilicate glass (SK 16). But, lead glass (SF 3) is hardly affected under the same Condition.
Some experimental results on the reflection characteristics of powdered materials such as powdered glass and phosphors are described. As for glass, absorption coefficients of several glass plates differing in chemical composition are first measured, then the plates are powdered, screened with silk cloths of 110 and 250 mesh. The reflectance of the powder is determined by comparing with that of smoked magnesium oxide measured beforehand. For those samples of powder, the reflectances of which are less than 0.75, the grain size affects the reflectance very little. In the spectral region where the absorption coefficient is greater than 1×103cm-1, the reflectance ranges from 0.05 to 0.1. If the layer of the powder is thick enough for the transmission to be ignored, and at the same time, if the reflectance is from 0.05-0.1 to 0.75, Kubelka's formula is found valid for the determination of absorption coefficient of the powder concerned. It is also proved experimentally that the absorption coefficient can be estimated by assuming the scattering constant to be 210cm-1 regardless of the refractive index of the material and the wavelength of the incident light. The ratio of the intensity of fluorescence emitted by the powder toward the source of incident light to the intensity of excitation can be much greater than the ratio taken on a transparent plate if observed under certain geometrical conditions. By applying the above results to the data obtained on powdered phosphors, the energy efficiency of fluorescence is found the greatest in the spectral region in which the absorption coefficient is from 102cm-1 to 103cm-1.
A hot cathode type hydrogen discharge lamp, operated by condenced discharge of 300 mA-30 watt, emitting a continuous spectrum in the u, v, region, has been developed. The energy distribution and the dependency of light output on the lighting time are measured and the causes of lowering the light output are discussed. The measurement of energy distribution of the lamp is made by taking into account the dispersion and effective transmission of the monochrometer and the spectral sensitivity of the detector (a photomultiplier). The emission intensity of continuous spectrum has its peak at about 2450Å. In the visible region of the spectrum, the emission curve shows a complex structure due to overlapping of various band spectra, while Ha (6563Å) line is markedly distinguishable from the back ground. The ratio of the intensity of Ha line to that of the continuous spectrum increases gradually with lighting time. The employment of fused quartz or the glass for the envelope of germicidal lamp as the material for window of the lamp is attended with some undesirable consequences such that a complex procedure of graded seal is needed or the light output of the lamp is affected by solari-zation effect. A new sort of special glass has been prepared which shows negligibly small solarization effect, good transmitting character in the u, υ, region and thermal expansion characteristics similer to those of hard borosilicate glass. Consequently, the variation of energy distribution of the lamp is remarkably reduced. In such a lamp, the mechanisms other than solarization effect, e. g., the decrease of hydrogen pressure due to clean-up effect and the damage of oxide cathode, may be as well responsible for the lowering of its light output. It has been recognized that the light intensity in the u, v, region is sufficiently great even at the end of 1100 hour lighting under severe conditions, and the lamp of this type is very satisfactory as the light source for spectrophotometry in this region.
Comparison of seven different systems of U. C. S. is made, the systems concerned being MacAdam's (u, v, ), N. B. S (α, β), Richter-Adams projective diagram (M1, M2), the new projective diagram, Adams modified root coordinate, Cube-root coordinate and Adams chromatic value diagram. For micro color differences MacAdam ellipses and for macro color differences Munsell scales are used. The new projective diagram is found appropriate for U. C. S., for it explains satisfactorily both micro and macro color differences and is of 0-1-0 in luminosity coefficients.
A new printing smoothness tester based on Chapman's principle has been constructed to indicate and record automatically the printing smoothness of paper. The electronic circuit used in the tester has been designed to utilize the specific feature of the instrument. For example, by reason of the intensity of incident light being not concerned in the smoothness of the paper, simply a fluorescent lamp is used as the source of intermittent light enabling the use of a. c. amplifier in the whole circuit. On account of the novel design of the circuit, the instruments is superior to any of the existing types of the tester in that the detected signal is not affected by leakage in the detector circuit and its level is very high and also that the operation is stabilized and the construction is materially simplified. Consideration given to the design of the circuit and a brief account on the printing smoothness of gravure paper are described.
Four functions are assumed for the intensity distribution curves of the lines of Kα1 and Kα2 rays. The apparent positions of the curves obtained by superimposing two curves corresponding α1 and α2 are calculated numerically, and the shift of peaks as a function of half-peak breadth are shown in a figure. As the breadths increase the peaks shift with respective rates towards an ultimate position that is the center of gravity of intensity of the doublet lines, however, it is not the case for asymmetrical lines and for lines having an inflexion at the peak.