Betsy, Camilla, Keita, Jason This morning, we took a closer look at eh small PSL-ALS beam path hitting the 1 and only mirror in HAM1 before heading to IOT1. It looked a bit clipped/elongated and was coming out of the light pipe toward the -Y side and veering off course onto the table (when compared to the new layout map). Given work on the path on the PSL table (for SPI), Jason and Keita went in to the PSL and revisited how the beam launches at the periscope. They could see scatter somewhere in the light pipe so it was probably clipping in there. Using the top ALS periscope mirror, Jason was able to yaw the beam back to the designed position of the mirror in HAM1 (Keita on the phone with Jason in the box, relaying to Betsy who moved the mirror and beam dump on HAM1). Now the beam looks nicely round, more centered in the entry viewport window, and runs along the table per the map we are aligning to D1000313-v19. We pointed the steering mirror so the beam leaves the table to also match the map. Next up is the X-arm peek and tweaking of alignments to get onto the IOT1 periscope mirrors.
First attachment shows the beam right after the viewport, shot by Betsy's cellphone. The beam looked much worse to my eyes on the viewer card.
Anyway, Jason and I found that
3rd attachment shows ALS-L2 where the beam was offset by about half of the open aperture radius of the lens mount (the lens itself is 1").
We used ALS-M2 and ALS-M3 to recenter the beam on two reference irises. 4th attachment shows ALS-L2 after this adjustment where the beam is more centered. Not perfect but much better.
On the 5th picture the beam shows no sign of clipping but the beam is close to the -Y edge of the baffle hole for the viewport.
Next Jason moved the top periscope mirror to steer the beam to where it's supposed to be in HAM1. The beam looked more centered on the baffle (6th picture).
7th picture: The location of the steering mirror for this beam on HAM1, which was set according to the HAM1 layout drawing.
8th and 9th show the PSL-ALS beam right after it is reflected by the steering mirror, and right before it leaves HAM1. We might have to fine-adjust this.
As Keita notes, before yawing the top periscope mirror he and I checked the 2 ALS alignment irises that sit under the periscope between mirrors IO_ALS_M3 and IO_ALS_M4 (the bottom ALS periscope mirror). The beam was off on both alignment irises to the -Y side, suggesting a beam shift had occured sometime between the end of the PSL laser upgrade in Jan 2022 and now (the last time I recall looking at this alignment was at the end of the laser upgrade); using an IR viewer Keita looked at the beam on IO_ALS_L2 (the 2nd ALS mode matching lens) and the beam was off-center on the lens as well. The beam looked decently well aligned (not perfect) along the IO_ALS_M1 to IO_ALS_M2 path, but beyond that it was well off. It's unclear what casued this shift. There was the recent SPI pickoff install last month that potentially could have bumped IO_ALS_M2, since they were working in that area, but I don't think that alone would be enough to cause the shift we saw. The beam needed to be walked in the +Y direction using both IO_ALS_M2 and IO_ALS_M3 to re-center on the alignment irises, but bumping only a single mirror would more than likely have caused an angular shift in the beam and be easily corrected using only the mirror that was bumped. This defintely was not the case, as we needed both IO_ALS_M2 and IO_ALS_M3 to walk the beam back to the irises. So as of right now I cannot say what caused this misalignment, it's entirely possible the ALS beam has been misaligned for a while.
As noted above, we used IO_ALS_M2 and IO_ALS_M3 to re-center the ALS beam on the alignment irises, and at this point the beam was no longer clipping when traversing the ALS light pipe. Back on the HAM1 table, the mirror that directs the ALS beam onto ISCT1 was still too far in the -Y direction for comfort (getting a little to close to the future home of the JAC and its associated optics). I then went into the enclosure and yawed IO_ALS_M5 (the top ALS periscope mirror) until the mirror in HAM1 was in its as-designed location. I've attached a picture I took of how the ALS beam now looks when entering the ALS light pipe; it's now a little closer to the +Y edge of the light pipe. Before adjustment the outside edge of the beam was very roughly 1" or so away from the light pipe edge (did not get a picture of this), now it's very roughly 1/2" or so away from the edge.