M.Lci^o:l5 



reference focus 

 object focus Z — = 



Figure 3. 



bottom lens 

 of objective 



double 

 refraction 



element 



reference focus 



object plane 



— double 

 refraction 

 element 



upper lens 

 of condenser 



object focu«J 



Diagrams of positions of focus of the reference and object beauts 



of light in interference optics. 



A. Double focus system. B. Shearing focus system 



object 



A, 



B. 



'igure U. Diar^rams of tvro kinds of reflection ODjoctive optics. Eyepieces 

 not shovm in illustrations, 



A. Conbination of reflection and refraction optical components. 

 E, Keflection obj^ctivn, no refracting lenses used. 



