avright: interference figures in objectives 307 



TABLE 1 



Table showing 'percentage intensity of transmitted light for different wave lengths 

 X after passing through polarizer, sensitive tint quartz plate {0.03 mm. thick and 

 cut parallel to the principal axis, and including an angle d with the principal 

 plane of the polarizer) and the analyzer whose principal plane includes an angle 

 <p with that of the polarizer. 



Extended comment on this table and figure is unnecessary. 

 From both it is evident that for d = +1°, the intensity of the 

 transmitted Ught is not the same throughout the visible spectrum 

 for a given angle cp between the nicols; thus for ?? = + 1° and 

 (p = 86°, the intensity of illumination is greatest in the middle 

 or green part of the spectrum about 550^^ and the resultant 

 color is of a greenish hue, while for ?? = + 1° and cp = 98°, the 

 intensity of illumination for the central part of the spectrum is 

 at a minimum and the resulting hue is of the nature of a minus 

 green which is magenta. Similar relations obtain for the angle 

 ?? = +2°. For still larger angles ??, the intensity of illumina- 

 tion throughout the spectrum is so great that the slight differ- 

 ences in percentage intensity for different wave lengths are not 

 sufTicient to dominate the hue of the total light transmitted. 

 It is only when the average intensity of illumination throughout 

 the entire spectrum is so slight that it approaches the limit of 

 threshold vision and perception of color differences that the color 

 intensity differences are most marked. 



