Yesterday we repeated the measurements of last week on the dependency of the DIFFp TY error signal on the SDB1 alignment, after Michal realigned the OMC last weekend (#43516 ).

IN this condition the asymmetry is not present anymore. IN the nominal position the error signal is very symmetric (see Figure 1) and when misaligning the bench on the "wrong side" it is still very symmetric (see Figure 2). Notice that last week, on the same misaligned position, the ratio between both halves of the parabola was 0.04 and now is 0.7, so the improvement has been significant.

So now the problem can be considered as solve, but it is interesting to know that we the DIFFp TY error signal is very sensitive to OMC misalignments.