2 7 6 



HIGH POWER MICRO-PROJECTION 



[CH. IX 



Bl. R The block carrying the radiant on the optical bench. 



Bl C The block carrying the condenser on the optical bench. 



Bl M The block carrying the microscope on the optical bench. 



Base Board The board bearing the track made of rods and serving as an 

 optical bench. 



Projection Table The table supporting the apparatus and holding it at the 

 proper height for use. 



The above method refers especially to high powers objectives 

 of 2 to 8 mm. equivalent focus. For powers lower than those just 

 mentioned one can get better results by the use of a main condenser 

 with a second element of 200 to 150 mm. focus and no substage 

 condenser, or by adopting the method given below or in 403 . 



Substage 

 p [_ Condenser 



FIG. 153. DIAGRAMS TO SHOW METHODS OF PARALLELIZING THE CONE 

 OF LIGHT FROM THE MAIN CONDENSER. 



A Method of parallelizing the converging cone of light from the main 

 condenser by means of a concave lens within the focus (/). 



B Method of parallelizing the diverging cone of light from the main con- 

 denser by means of a convex lens beyond the focus (/). 



Arc Supply The right-angled carbons of the arc lamp. 



L, L 2 The first and second elements of the triple, main condenser. 



Water Cell This is to remove the radiant heat. 



Axis The principal axis on which all the parts are centered. 



/ The principal focus of the second element of the main condenser. 



P. L. Parallelizing lens. Concave in A, Convex in B. 



Substage Condenser This is the first or lowest element of the substage con- 

 denser of the achromatic form (fig. i5oA). See also fig. 150 B. for the Abbe 

 form of substage condenser. 



