DEALING ~TH TEC~CAL PROBLEMffi RELATING TO THE PRODUCTS, PROCESSES AND INVESTIGATIONS OF THE PHILIPS INDUSTRIES

For many years electronics has been engaged in the problems of amplifying very weak currents and voltages. In rece~t years, partly owing to the stimulus of teleuision, a new branch of,electronies, that"'is, the intensification. of light, has ·emerged. The original object of this development was the conversion of long-wave; into short-wave light ("wavelength-transformation") which was investigated in the Philips laboratóries at Eindhoven as long ago as 1934. Now, however, the. emphasis is on luminance intensification. with special reference to the intensification of weak fluorescent images. • The first. article on the X-ray image intensifier to appear in this Review teas published in 1952; since then, laboratory experiments and practical tests have produced much new and interesting information concerning this intensifier, and it is now considered worth while to publish one or two articles describing these developments. The main points considered here are: the minimum size of detail perceptible with the image intensifier; the optical problems involved; photography and cinematography with the image intensifier, The present articles refer mainly to the existing type of image intensifier, Little is said as to the probable future trend of development in image intensification ; this does not imply, however, that the present results are éonsidered the last word in this field. On the contrary, we should emphasise that the subject is still developing and we hope to report further progress in due course.