each other, the floating mark, as we already said, rigorously follows said mo- 
vements. 
We have executed stability tests, along these lines and we have been able to 
note that feeding current to the instrument an entire day cutting off the current 
in the evening and repeating the calibration the morning after, the measure ori- 
gin has remained unchanged within the normal reading tolerance limit. 
By taking advantage of the fact that we have completely projected anew the 
optical system, we have also notably improved both the observation field, increas- 
ing it, for magnification 8, to 23 mm, as well as the entry and exit pupil, thereby, 
increasing the theoretical resolving power of all the system. 
  
Fig. 6 - General view of the TA3/A « Nistri » Stereocomparator 
Apart from the modifications and improvements described, the possibility to 
substitute the measuring and recording electromechanic system with the electronic 
optical system based on the interferential fringes (moire) principle has been studied. 
Even if this solution is more expensive, main advantages are obtained: 
1) the independence of the measure from the lead screw accuracy to which are 
exclusively entrusted the translation tasks, both slow and fast; 
2) the possibility of obtaining faster displacements, as well as recording on flight; 
3) the possibility to obtain coordinate values up to three units of the third 
decimal (micron) in contrast with the electro-mechanic measuring system that 
only allows to reach the even micron values. 
PRINTED IN ITALY 
OTTICO MECCANICA ITALIANA S.p.A. 
Via della Vasca Navale, 81 - Roma 
60.168 X 20 
Die 
Die Funktic 
wird auf th 
k-Werten di 
in den Relaf 
The Accura 
states the r« 
has in the p 
the horizont 
in equn. (5), 
p is direct 
reflected fr« 
in a nomog 
[M is deri 
AD = P, 
Précision de 
énonce une 
cet objet « 
chacune de 
(illustr. 1). 
2. Ils expr 
proportio! 
respeetivem 
représenté « 
de sorte qv 
AD PD, 
l'oeil humai 
1. Vorbeme: 
gehende 7 
handlung!. 
Eine einget 
ist bislang 
gesichts fri 
nauigkeitsa 
Meßtechnik 
erlangt hät 
Nachdem i 
Bildkontras 
techniseh d 
angebracht 
damit einh 
ist. Hiervo 
troffen, da 
Luftlicht 1 
häufigsten . 
2. Bezeichn 
definiert, di 
D, (vgl. 
Mel 
{Um 
1 Die Origir 
leihweise üb