Recombined ray 

 ( Destructive 

 Interference) 



Diffraction 

 plate 



Objective 



Condenser 



Annular 

 Diaphragm 



Phase retarding 

 material 



Microscope stage 



Figure 11-13. Diagram Showing the Principle of Phase Microscopy. 



deviated and undeviated light will emerge from the diffraction plate in 

 phase and recombine to give increased brightness (constructive inter- 

 ference) of the object (Figure 11-14 (b)). 



Phase-contrast microscopy can be used to measure the refractive index 

 and solid concentration of cell structures by utilizing the method of 

 immersion rejractometry. This method involves the immersion of cells 



SURVEY OF CYTOLOGICAL TECHNIQUES / 231 



