. The Bell System technical journal . or 270° the fieldis dark as we previously explained). Consequently, if we could see alongall directions at once we would see a pattern of concentric dark rings on adark cross as shown in Fig. But we can see along all these directions at once if we employ a properlyplaced lens for a lens can converge all these rays to one point where an eyecan be placed for viewing. Thus an eye at e, Fig. , will see, in the direction e po, the ray that SPECIFYING QUART/. CRYSTAL ORIENTATION 249 started along s po. It will see along e pi the ray that started along
. The Bell System technical journal . or 270° the fieldis dark as we previously explained). Consequently, if we could see alongall directions at once we would see a pattern of concentric dark rings on adark cross as shown in Fig. But we can see along all these directions at once if we employ a properlyplaced lens for a lens can converge all these rays to one point where an eyecan be placed for viewing. Thus an eye at e, Fig. , will see, in the direction e po, the ray that SPECIFYING QUART/. CRYSTAL ORIENTATION 249 started along s po. It will see along e pi the ray that started along 5 point on the lens will have associated with it a different directionin the crystal. Therefore the eye will see a pattern like that of Fig. is the principle of the conoscope. In the conoscope (the name meansconical viewing) the source 5 is replaced by the image of a source, theimage being cast by a lens; see Fig. Thus by the use of two similarlenses we get twice as much working space as one lens would POLARIZER LENSCRYSTAL Fig. —The principle of the conoscope
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Keywords: ., bookcentury1900, bookdecade1920, booksubjecttechnology, bookyear1
