After adjusting the laser angle, PI got much improved. But, the test 2 phase shows a lower PI than test 1 in most of cases, the reason for that is still unclear. The following is the result of 9 measurements without drifting.

train1 PI: 0.50

train2: 0.42

test1: 0.39

train3:0.61

train4: 0.63

test2: 0.06 ???