Naoki, Camille, Julian, Rahul
Summary: We measured beam profiles in HAM7 and HAM6 using the SQZ beam, after the PSAMs offloading work from 75677 75709 and the alignment work from 75732. We noticed that there is a lot of astigmatism on the beam in HAM6, but not in the HAM7 location that we were able to reach with the profiler.
Details:
In HAM6 we measured at three locations marked by the letters a,b,c in the sketch that Julian will attach. The red lines in the sketch show the irises.
Location 6A is 1.75 inches from the iris, Location 6B is 2 inches from the iris (closer to OM1). At location 6C we measured the beam in reflection off OM1, 23.25 inches after OM1. (The fast shutter is further in the -Y direction in chamber than what is shown in the CAD drawing). We also would like to measure at position 6D, once the second iris is removed.
We also measured beam profiles on the -X side of the HAM7 table, location 7A is 6.25" in the +X direction (closer to ZM5) from the iris, 7B is 8.25" from the iris in the + X direction, and location 7C is 12" from the iris in the +X direction. We weren't able to move the profiler further into the chamber without blocking the beam heading towards FC1.
We measured 13.5% widths, with A1 as the vertical axis and A2 as horizontal.
| location | ZM4 PSAMs strain gauge [V] (PZT request [V]) | ZM5 PSAMs [V] | A1 Width [um] (standard deviation) | A2 Width [um] (standard deviation) |
| 6B | 0.82 (0) | -4.14 (0) | 1392 (8.7) | 1573 (9.9) |
| 6B | 4.38 (100) | -4.14 (0) | 1406 (7.3) | 1584 (6.3) |
| 7B | 4.39 (100) | -4.14 (0) | 2001 (6.4) | 2017 (6.1) |
| 7B | 1.0 (0) | -4.14 (0) | 1928 (5.6) | 1924 (5.9) |
| 7B | 0.98 (0) | -0.52 (100) | 2200 (8.2) | 2212 (9.4) |
| 7B | 4.31 (100) | -0.52 (100) | 2276 (9.5) | 2303 (9.3) |
| 7B | 8.49 (200) * | -0.52 (100) | 2363 (11.0) | 2412 (13.8) |
| 7B | 8.53 (200) | 3.57 (200)* | 2611 (9.0) | 2691 (7.2) |
| 7B | 5.74 (100) * | 3.59 (200) | 2539 (13.7) | 2603 (18.1) |
| 7A | 5.72 (100) * | 0.64 (100) | 2387 (13.5) | 2446 (13.1) |
| 7C | 5.715 (100)* | 0.63 (100) | 2374 (11.0) | 2415 (9.5) |
| 6A | 5.7 (100) * | 0.625 (100) | 2074 (9.9) | 1611 (7.4) |
| 6C | 5.7 (100) | 0.612 (100) | 1670 (10.2) | 1618 (7.0) |
* strain guage still drifting
Stll left to do:
- Measure distance from HAM6 first iris to OM1.
- Measure distance from HAM7 iris (on -X side of table) to ZM5.
- take a better photo of the beam position on ZM5.
- try to put beam profile in location of iris near OM1 (location 6D).
Useful distances from Don:
Don Griffith sent us some useful distances in HAM7 which are useful for interpreting these measurements, based on the CAD model that he updated in in March 2022 based on the as built photos of HAM7 (D1900365-v1).
- B:M4 (last optic on VIP) to ZM4 = 1086.36mm
- ZM4 to ZM5 = 1681.23mm
- ZM5 to Beam Diverter + 1183.54mm
- ZM5 to Edge of Table = 1822.70mm
- ZM5 to ZM6 = 4680.61mm
Attached are new and final sketches (these should be used for future analyses) of the beam profiler positions with distances.
Note: we measured a distance in HAM7 from the edge of the table to ZM5 of 1841.5mm, whereas Don Griffith CAD model shows a distance of 1822.7mm.
Attached is the sketch of HAM6 and pictures of the beam profiler position.
Sheila, Naoki
We measured several distances as follows.
From first iris to OM1 in HAM6: 53.75''
From ZM5 to second iris in HAM7: 68.5''
From edge of table to second iris in HAM7: 4''
Then we removed the irises in HAM6 and measured the beam profile at the position of second iris, which is 13.5'' from OM1.
A1: 1285 (6.7)
A2: 1426 (9.2)
We also measured the seed power at several locations. The seed coming out of HAM7 is 1.05 mW and the seed in HAM6 is 0.71 mW, which makes sense since the SRM reflectivity is 68%. The seed reflected by OPO without dither lock in SQZT7 is 30.5 mW.
We tried to take a photo of the beam and the ruler in ZM5, but it was difficult to read the ruler by camera or our eyes so we roughly measured the beam position in the baffle of ZM5. The hole diameter of the baffle in ZM5 is ~3 cm and the beam is ~1 cm below the top of the hole so the beam in ZM5 is higher than the center of the hole of the baffle.
The beam profile measurement in 75770 was done at 6D in this figure. The ZM4 and ZM5 PSAMs strain gauge [V] (PZT request [V]) are as follows.
ZM4: 5.68 (100)
ZM5: 0.52 (100)