Lines of Equal Intensity about the Point 



of Intersection of Fraunhofers 



Diffraction Bands. 



By 

 H. Nagaoka, Riéakuhakushi. 



The lines of zero intensity in diffraction figures are not sharply 

 defined, but appear as bands. Where two such lines cross one 

 another, the adjacent parts are usually dark, whether the light be 

 monochromatic or not. To obtain good coincidence between experi- 

 ment and calculation it will be advisable to investigate the shape of 

 the dark curves about the intersecting bands. 



When there are two systems of bands in Fraunhofers diffraction 

 phenomena, the intensity of light in the focal plane of the observing 

 telescope is generally expressed by the square of the product of two 

 functions, the evanescence of which gives rise to separate systems of 

 bands. Denote these functions by <f and tf, which may be considered 

 as functions of coordinates x and //, referred to axes fixed in the focal 

 plane. The intensity of light at any point re, //, will be 



I = f(x,y) = f. p- 



The intensity at an adjacent point x+£, y + y will be 



ov 



