i 
    
  
fl 
U 
6.0 
  
  
  
  
  
  
, 
| 
  
  
  
  
-26- 
  
  
  
  
  
  
  
  
  
    
FIGURE 10. Contour maps of original version 
of DBA reseau platen under various circum- 
stances. 
a. after original manufacture, March 1974 
(rms unflatness = 1.5 um) 
b. after initial use on Vermont Project, 
June 1974 (rms unflatness = 2.2 um) 
c. after Atlanta Project, June 1975 
(rms unflatness = 5.3 um) 
d. same as c but with application of film- 
flattening vacuum (rms unflatness = 
10.2 um) 
e. change in flatness with application of 
vacuum (difference between d and c). 
  
  
  
p 
=;