The entry was quite confusing owing to many misleading wordings.
- The PS2 should be calibrated "as is". (i.e. should be calibrated with the frame)
- The previous calibrations with the highly reflective surface were 0.32V/mm and 0.26V/mm, respectively.
This time you have 0.10V/mm (with an undescribed surface). The ratio is not 32 but 3.2.
- The DC output of PS2 on the shaking setup was 2.5V. The DC output seen in the plot is 3.5V-ish.
This suggests the possibiliteies:
1) The surface has slightly higher reflectivity than the frame
2) The estimation of the distance between the frame and the PS2 during the TF measurement was not accurate.
- The word "DC coupling level" is misleading. I guess you mean the DC value of the vbration isolation transfer function
of the suspension.
I have re-calibrated the photosensor I used to measure the displacements of the TT frame (what I call "Photosensor 2").
As before, the linear region is about 15.2mm to 25.4mm. It is characterized by the slope -0.0996 V/mm (-0.1 V/mm). Recall that photosensor 1 (used to measure mirror displacements) has a calibration slope of -3.2V/mm. The ratio of the two slopes (3.2/0.1 = 32). We should thus expect the DC coupling level to be 32? This is not what we have for the DC coupling levels in our data (2.5 for flexibly-supported, fully-assembled TT (with EDC, with bar), 4.2 for EDC without bar, 3.2 for rigid EDC without bar, 3.2 for no EDC, with bar, 3.2 for no EDC without bar) . I think I may need to do my calibration plot for the photosensor at the frame?