Align the laser so that the beam hits the middle of one of the faces of the prism as shown
Tightening the small c-clamp 1/4 turn allows light to take the straight path. Do not overtighten.
The photocell is connected to the demo meter and the voltage with the beam being deflected can be compared to the voltage when the beam goes straight through the middle.
You can look through the prism at the yellow “post-it” note as you tighten and loosen the clamp. You alternately see and not see the “post-it” as the ‘window’ opens and closes.
