On the New Method of Manufacturing a large-sized Parabolic Mirror answering the True Nature of It.

Abstract

The search-light mirror has been manufactured strictly respecting the optical efficiency at all events. In other wovdo, in its manufacturing, the curve of the mirror has been geometricaly measured. The mirror manufacturing companies of the world have attached importance to this point. Therefore every company has tried many experiments to produce proper articles as a manufacturing factory for comparatirely long period. It may be said that the ready-made factory cannot produce such an effectual seach-light mirror. In the 1st and 2nd chapters, I made this fact clear. For this reason, even in the time of peace there is need of keeping their manufacturing arts. If the searchlight has no ‘use except for the military purpose, then its continued production will be very uneconomical. In spite of the fact that the manufacturing method belongs to the delicate industry, the manufactured ones have no use except for military purpose. Then I discussed, in the 4th chapter, about the nature of the curve of search-light mirror, for the purpose of explaining whether it is neccessary to set the importance on the only point of elevation of optical efficiency or not, when observed from the point of the nature of the search-light mirror. And, as the result of this discussion, I narrated that such a small progress on the optical efficiency of mirror will affect on the luminous efficiency of search-light, and explainnned that the elevation of optical efficiency in future will has so little effect on the elevation of the luminous efficiency. On the other hand, I refered to the relation between the absorption of light by air and wave-length of light. By this, I ascertained that, if we make the mirror surface that it may have a special curve from the point of wave-length of light, we could easily make the variation on luminosity which could be discerned by the retina, and by this I concluded that the future progress would depend more on metallic mirror rather than on glass mirror. Then I set the hope for future progress in study of the mauufacturing method of search-light mirror on metallic one that can illuminate long wave-length light. And as the study of the method, I hope that, though the optical efficiency is dropped to the degree, which has no effect on luminosity in fact, the method that can produce, whenever it is required, even in a most unprepared condition without requiring every-day discipline as the special delicate industry, is the very important problem to study from the stand point of their national economy at peace as to-day. Secondary T hope that, if the manufacturing method of it belongs to a special delicate industry and if the production of it must be continued in war and peace as continued by all the factory of the world, the method which manufacture the mirror that can be used for other purposes which require more delicacy that military purpose, should be studied. We tried to find the method, which answers the above two hopes, in the methods of all the factory of the world, but in vain. The method showed in the 5th chapted which has been invented by me is the only one to answer the above second hope and the method in the 6th chapter is the one to answer the 1st hope. © 1924, The Illuminating Engineering Institute of Japan. All rights reserved.