NEUTRAL AND AXTI-XEUTRAL QUADRANTS 



159 



to handle at present even when the Vectograph method is applied to 

 making the zonal polarizer. 



The polanret system illustrated by Fig. III. 14 has been successfully 

 incorporated into microscope objectives with relatively long focal 

 length and low numerical aperture. Only moderate difficulties are en- 

 countered in objectives of 25-mm focal length, N.A. 0.17, and of IG-mm 

 focal length, N.A. 0.25. Considerable development work will be re- 

 quired in adapting the method to oil immersion objectives. A practical 

 solution may very well utilize the multipupil principle (Osterberg, 

 1948a) and, in particular, the multipupil system described by Frangon 

 (1950). (See also Section 8.) 



M^^A 



Fig. III. 15. The neutral and anti-neutral quadrants. A denotes the transmission 

 direction of the analyzer. Ei and E2 denote the positive direction of vibration of 

 the undeviated and deviated waves respectively as these emerge from the micoid 

 disk. The neutral quadrant is I or III. The anti-neutral quadrant is II or IV. 



9.3. Neutral and anti-neutral quadrants in polanret systems 



Polanret sj'-stems possess an important and advantageous peculiarity 

 in that the phase difference between the undeviated and deviated waves 

 undergoes a sudden jump of }/2 wavelength as the transmission direction 

 of the analyzer is rotated out of the neutral quadrant. This phenomenon 

 will be explained for the case in which the conjugate and complementary 

 areas are polarized at right angles. 



In Fig. III. 15 let Ei and E2 be the positive directions of the electric 

 vectors as they emerge from the conjugate and complementary areas, 

 respectively. If the transmission direction .4 of the analyzer lies 

 between Ei and E2 as in Fig. III. 15.4, the projections OM and ON of Ei 

 and E2 upon A point along the A direction. In other words, the direc- 

 tions of the electric vectors which result from the interaction of Ei and 

 £'2 with the analyzer are alike. If the transmission direction A of the 



