| TMS (PIT, YAW, V) | ITMX | ETM | |
| PD1 | (102.5, -209.5, 2.37)0dB gain | (54, -79, 5.85) | |
| PD4 | (171, -271, 2.38)0dB gain | (88, -45,5.77) | |
| alinged | (136.75, -240.25) | (71, -62) |
After alinging TMS and the ITM using the bafle PDs, I was unable to find light on the ITM baffle PDs using the old ETM referece (alog 9126).
I found some fringing at: ITM 75 -59 ETM 384, -77 TMS 136.8, -240.3. The ETM was moving too much to make a reasonable alingment. Hugh, Jeff and Jim helped to get both the ETM and ITM to level one isolation, so things are moving less now.
By misalinging the ITM I measure 12830 counts on refl B. If I misaling the ETM by 40urad, I can clearly see two return beams, a brighter one from the ETM and a less bright one from the ITM. Misaligning the ETM by 80urad, the etm return beam is no longer on the refl B PD. I adjusted the ITM alignment to maximize the power on the refl B PD, at PIT 75 YAW -59 there are 2850 counts on refl B. Blocking the refl B PD completely we have 52 counts. I also misalinged the itm to see the signal disappear, so I do believe this beam was really from the ITM.
The ratio of the ITM return to the ETM return beam is (1-Retm)^2*Ritm/Retm. Assuming that the ITM reflectivity is 99%, this gives Retm=63%. This reflectivity will only get lower is the ITM reflectivity is lower than 99%. With Retm=63%, our measurement of the return beam power from monday night (alog 9171)means that the TMS effiicency (one way) is 78%, matching better with Keita's prediction (alog 3077) of 82%. In the first version of this alog I made a mistake, and wrote that the reflectivity was 53%.
I measure 12uW of 532 arriving on ISCT1 with the ITM misalinged (single shot beam, about 34mW input from ISCEX) ), there is 1.6uW on the DC PD monitoring the X trans. The DC PD does not seem to be working, it is cabled (R4 ISC1:2) but changing the gain on the medm screen does not change the monitor output for this channel. I also alinged the single shot beam onto the Comm BBPD, there are 3.5mW there with the ITM misalinged. The slow controls readout of this PD is also not working, but I can see that the PD is working in H1ALS-C_COMM_A_LF. I added a -62 counts offset (the dark offset) now get around 40 counts with 3.5 uW on the PDs.