The wedge angle of the prism "A1" was measured with the autocollimator (AC).
The range of the AC is 40 arcmin. This means that the mirror tilt of 40arcmin can be measured with this AC.
This is just barely enough to detect the front side reflection and the back side reflection.
The measured wedge angle of the A1 prism was 0.478 deg.
Ideally a null measurement should be done with a rotation stage.