I measured the visibility between LO and BAB with improved reflection mode matching and new beam spot. The measurement method is same as the previous measurement.

To know the BAB power during the measurement, BAB pick off power was also measured in CCFC port. Fig 1 shows the BAB power before AMC and the BAB pick off power. From this measurement, we can know the calibration factor from the BAB pick off power to the BAB power before AMC (bottom plot in Fig 1). The calibration factor is 0.25. The LO power was 1.21V. The offset of visibility was 8.5mV and the offset of pick off was 3.8mV. 

The measured visibility and BAB pick off are shown in Fig 2. The 10Hz modulation was applied to IR phase shifter. To calculate the visibility, I divided this data into 500 segments with 0.02s step (Fig 3) and calculated the visibility in each segment (Fig 4). From the histogram, the visibility is 0.98(1) which corresponds to optical loss of 4(2)%. We could recover the good reflection alignment!