fal 
  
4 
4} 
hi i 
  
abs. 1 
E in 
  
T€ 
á a 
  
  
  
  
  
  
  
  
  
i LE 
  
  
      
    
  
    
  
/ummnated 
= - — eJ oslng man, 
Fig. 18 
óx and dy from equations (6a) and (6b) represent the projection errors with respect in 
the cross. As the measurement is done with the illuminated floating mark, which has à 
fixed position, we have to consider 
the final projection errors 0x, and ôyp obtained wie 
measuring with the illuminated floating mark. We get from fig. 18 
0Xp = OX + 02 ctg (50— 5) 
/ 
ÖXp = €; tate f+ ctg (50 — 
ctg (50— ; ) 
+ € sin 50 — 
cos a 
+ € tes + cig (50 
+a, cos 50 — 5) sf + ——— 
óyp — 0 
z) 
/ — sin (50— 5) tg — cos 50| 
à ctg (50 — 5 
— cos 50 — : — — — sin 50 
cosa 
  
sin (50—) 
  
To get an idea about the magnitude of these errors we will compute a table of fk 
factors e, for a = ß = --30£, providing maximum values. 
  
  
  
  
  
  
TABLE 1 
| ox | X, | dy | óz 
e, | +0.38 | +185 | +0.15 | +05 
e; | --0.58 | 70401 — | +0.33 
€ | — 0.11 | +115 | m 
e | +039 | — 2.12 | — | +0.06 
  
  
As an example it may be assumed e, = e, = e, — e, = +0,01 mm. The final prot 
ion errors are then xp = —0,2 u; 
    
oyp = 0. 
  
; Gimbal axis 
The situati 
gxiliary syste 
uations (1). 
The total ] 
times enlarged 
hundles of ray 
Note: Err 
çà Weele [1] 
mean square 
Conclusion: 
Due to the 
«ble to separat 
tom the ones i 
i the cross. Wi 
(he) (this 0Z ap 
more, an error 
A 
| 
| 
  
  
Fig. 19