REFLECTED-LIGHT MICROSCOPY 



]41 



No light passes into the objective. A surface unevenness in the object 

 diffracts light which enters ihe objective. The unevenness is bright on 

 a dark ground. Measuring the surface slopes is facilitated by using 



T.'t 



; 1 



\J 



Fig. 4.19. Reichert's device (Epilum). 



a pin-point source whose image is occluded by an opaque screen 

 (Fig. 4.21), The pin-point source is imaged at F' in the focus of the 



L 



F-4* 



Fig. 4.20. Leitz's ultropak. 



microscope objective O^. The rays, emerging therefrom, form a beam 

 of parallel rays which, after being reflected on the surface P. image 

 the source F' at F[. In Fig. 4.21, the opaque screen D is shifted to 



