乍一想,在一个小的阴极射线管上产生显示,然后用透镜系统(如图)把它投射到屏上。或把它用照相的方法照下来,然后通过胶片投射出去,似乎并不困难。但是用电子枪轟击荧光屏来产生一个很亮的光源比起单纯做一个很亮的投影灯要困难得多。用电子轟击光体产生它可能有的最强的亮度,从而在一个12×16呎的屏上产生的显示,其亮度只有电影的1/8。 At first glance, a display is made on a small cathode-ray tube, which is then projected onto the screen using a lens system (pictured). It may not seem hard to photograph it or photograph it and project it out through film. But bombarding the screen with an electron gun to produce a bright light source is more difficult than simply making a very bright projector. Electron impactors generate the strongest brightness that it may have, resulting in a 12 x 16 foot-on-screen display with only 1/8 of the brightness of a movie.