I decoupled ETMX MN photosensors more precisely.
Sensor decopling with the following method seems fine.

Detail:

Relation between measured signal vector D') and decoupled motion vector (D) can be written as follows with coupling matrix A.

So, if we can measure the coupling matrix A, we can calculate the decoupling matrix A^-1.

To measure coupling matrix, I used following resonances for the decoupling of ETMX MN photosensors.

I injected white noise around the above resonant frequency and measured the gain /phase from the excited DoF to the other DoFs at the resonant frequency (for example, TF from K1:VIS-ETMX_MN_DAMP_L_IN1_DQ to K1:VIS-ETMX_MN_DAMP_T_IN1_DQ).
Data are stored at /users/VISsvn/TypeApayload/ETMX/TF/Measurement/2024/0603/, and followings are the example of the measurement results when L resonance was excited.

Since only L has a resonance at 2.48 Hz, peaks at 2.48 Hz on the other DoF signals should be coupling.
So, coupling matrixelement can be obtained from the measurement as follows:

Here, absolute value of each element is same as the gain value and sign is same as the sign of cos({phase of coupling}) (eg. element L2T is -0.184646 in this case).
Note that, since L and T motions really make P and R motions, respectively, measured L2P and T2R couplings might not be sensor couplings, so I set zeros for those two elements.
Then, I can obtain the decoupling matrix from the inverse of coupling matrix A.

Figure 1 shows the obtained decoupling matrix, which implemented ETMX_MN_SENSALIGN matrix.
Figure 2-7 show the TFs from each DoF excitation after decoupling.
Decopling of sensors seems fine.

Note:

This time, measured T2V, P2T, P2V coupling is small enough, so I ignored them for calculating decoupling matrix (I set zeros at T2V, P2T, and P2V elements in coupling matrix).
L2T and T2L coupling becomes large after decopling matrix was implemented but it seems to be due to actuator coupling, so I will proceed actuator decopling and check what will happen after that.