To investigate the birefringent behavior of the PRMI (9324 9325), the cavity scan measurement of the PRMI has been performed tonight using the same method as reported in 9246 9276.
The results show that:
1. The main peak of S pol and that of P pol are slightly shifted from each other. The amount was ~1/200 *FSR = 5 nm in average. The direction of the shift seemed to be random.
2. The second-highest peak of P pol exists between the second- and third-highest peak of S-pol. I don't know how to interpret this result.

I put the dtt files of the results in /users/Commissioning/DRMI/PRC_Scan/20190623.
The measurements were done four times in total. PRM was pushed in + L in two of them, in -L in the other two.
Here I put an example of the results.