Katie Morzinski – Page 3 – Extreme Wavefront Control Lab

MAPS May 2024A Night 5: Conjugate planes

Our science cameras image the star in the focal plane, and our wavefront sensors image the star in the pupil plane. A conjugate plane is where your alignment needs to be in order to get those images in focus. After tonight we are wondering whether our VisWFS pupils are conjugate to the telescope pupil.

Summed VisWFS pupils. Why aren’t the edges sharp? Why are the edges raggedy? [Image description: photo of a camera display, black background, white photons in four imperfect images of the telescope pupil, which is round with a hole in the center like a doughnut.]

Tonight we started with Do-Crime on the IR WFS and MIRAC photometry, then moved on to CACAO on the VisWFS when Jared and Olivier called in on Zoom. We first closed the loop on the 50-modes response matrix from yesterday, and it still worked to the extent that it tightened up the PSF!

We next wanted to explore why the higher-order modes had been unstable and why our pupils still looked raggedy and soft on the edges. Because we had trouble calibrating the edge actuators of the ASM in the lab, we have always blamed the edge weirdness on the imperfect ASM calibration. However, tonight we decided to try a Hadamard matrix diagnostic, which pokes each actuator individually (but efficiently) and measures the result on the WFS. The result was that some parts of the mirror were having no effect whatsoever on the wavefront. One of those regions was where the shell is contaminated, but there were other regions too. Even after Amali put some disabled actuators back in the loop, the result was the same.

Olivier started wondering aloud whether our pyramid image was actually conjugate to the telescope pupil. If it’s out of focus of the pupil plane, then the response would no longer be linear, and you would also get mixing of phase and amplitude of the electric field. This could explain why the pupil images don’t look sharp or round.

We did a test where we translated the star about an arcsecond away from the tip of the pyramid, and saw the pupil image shift by around 4 pixels. The shape of the central obscuration changed too.

Left: Four pupil images on the VisWFS evenly illuminated when the star is centered on the tip of the pyramid. Right: After we nod about an arcsecond to put most of the light in the upper right pupil image, the image has shifted a few pixels. If the pyramid was conjugate to the pupil of the telescope, then they shouldn’t have moved.

So we switched to the IR WFS to see if we could see a similar shift. The IR pupils look sharper than the Vis, and they didn’t shift much if at all.

Left: Four pupil images on the IR WFS evenly illuminated when the star is centered on the tip of the pyramid. Right: After we nod about an arcsecond to put most of the light in the upper right pupil image, the image didn’t seem to shift much. So the IR WFS seems to be in better focus to the telescope pupil.

This was about as far as we got with CACAO before it was time to switch back to Do-Crimes. Tomorrow night we will use the IR WFS and compare CACAO and Do-Crimes corrections.

The song of the night is “Gimme more” by Britney Spears (2007)

The best 15 minutes of the day were flying a kite with Amali, Manny, and Bianca. It’s a homemade kite made by Amali, and the gusts across the peak and around the dome are not very laminar, so it was hard to get a sustained flight, but we did get it to dance and dive in the wind. And we also had fun trying but failing to see the green flash again.

That leads us to the bonus song of the night: “Let’s go fly a kite” from Mary Poppins

MAPS May 2024A Night 4: CACAO 50

We made a lot of AO progress tonight! We switched over to the VisWFS and CACAO, and started with measuring latency (mlat). Jared and Olivier joined us on Zoom and helped debug some settings that were causing us to think our hardware latency was noisy and to suspect timing issues or simlinking the slopes instead of the pupils, but now we think it was actually just a normalization. Here is a nice mlat we got:

Screen grab of the AO control computer while taking hardware latency (mlat) measurements. Top left is the pyramid pupils, small plot to its right are the slopes, medium plot to its right is the DM display, terminals in upper right corner are CACAO, ASM GUI is in lower left, gain GUI is in lower right, and the gnu plot at center bottom is the mlat result: The purple curve is from earlier in the night before restarting CACAO and getting rid of our settings, and the green curve is the new mlat result after debugging the noise/timing/simlinks/settings.

After the mlat’s, we closed the loop on the first 3 modes with our best response matrix from March. It worked!! But we couldn’t do higher-order modes — probably because the pupil and alignments had changed. So we moved on to take a new response matrix, but closing on the first 3 modes using the March matrix. We also tested tip/tilt offloading to the mount. And after some investigation of why some of the modes looked noisy or didn’t have much power in them via plotting self response matrices (selfRM), we continued and took a 50-modes calibration. We closed the loop with it and (even though we had to put tiny gains on modes 37-50), it was actually correcting and improved the PSF!

It was cloudy this afternoon and there were a few patchy clouds at sunset, but pretty soon it cleared up and we had a nice night with seeing around 1-1.3”. Earlier in the day Jarron opened the warmed-up BLINC and removed the baffle that was vignetting his pupil, so tonight we all had good pupils for the first time and we were able to get some nice looking PSFs!

When Jared and Olivier went to bed it was time to end our time with CACAO for tonight, and switch to Jacob and Suresh’s project with DO-CRIME and the IR WFS. We finally ended at dawn, a very full and useful night!

The best 15 minutes of the day were trying to watch the green flash at sunset with Amali, Lauren, and Bianca. (We didn’t see it though, but we used the trick Gill taught us.)

The song of the night is “Toxic” by Britney Spears (2004)

MAPS May 2024A Night 3: Alignment Crimes

Cell phone photo (!) by Suresh of the Milky Way over the MMTO last night. [Image description: a star-filled sky, and a cloudy-looking galaxy band, over a telescope dome on top of a pine-forested mountain.]

The nice thing about observing at the MMT rather than Magellan (even though they don’t haul food, meal prep, cook, nor clean dishes for us here) is that when you have an urgent need for one of your engineers to come up, it’s only a 2-hour drive (rather than a 2-day flight/drive) from Tucson! Tonight Grant kindly came up and got us aligned.

Why did we need to do alignment again? Well between the telescope and the AO bench we have so many degrees of freedom, and the telescope staff that we work with have different ideas about what to do, and our team has different ideas about what to do, that we had gotten very misaligned and had to start all over again. As I mentioned yesterday, Tim and Ben got us aligned to the chief ray of the telescope. Tonight Grant, Oli (remotely), Bianca, Manny, et al then went back to our first upstream optic: the dichroic — and starting there did a beautiful iterative alignment (even having to move the MOUNT of periscope 1 because it had run out of range) and got us filled pupils! (Especially after Amali also encouraged some of the edge actuators to do a better job holding up their edges.)

Yes we are still a bit unclear as to why the dichroic was so far off (since we hadn’t touched it and we THOUGHT we were on the chief ray in January when we installed/aligned it), and why periscope 1 had wandered so far. But I think it’s just a complex system with many parts controlled by different teams and we have different staff (both from MMTO and MAPS) at different times so we never quite know if we are doing things the same way every time, no matter how hard we try, especially since the system is still so new and we are constanly making adjustments and working out kinks anyway.

So we will continue to learn more about the situation, but thanks to Grant for coming up and Oli for being on the phone and to everyone for filling our pupils once again!

Grant looking at pyramid pupils on a laptop at the Cass of MMT in the dark. [Image description: Grant is peering at the pupil image, and about to reach in and adjust another optic and watch the change.]

After this we went on-sky and Andrew got the IR CTL pupil tracking working! And then Jacob and Suresh took Do-Crimes interaction matrices and closed the loop with a 20-modes loop! We were debugging this at dawn when some patchy clouds suddenly showed up (after a beautiful clear night with 0.8-1” seeing) and so it was time to call it a night (It’s a night!).

Amali’s completed Tunisian crochet project! [Image description: A scarf is draped across 2 chairs. The scarf has a geometric pattern that morphs into the word “MAPS” and has colors of dark blue, reddish-orange, and whitish-cream.]

The best 15 minutes of the day were one of my trips up to see the alignment in the dome.

Song of the night: “I’m a Slave 4 U” by Britney Spears (2001)

MAPS May 2024A Night 2: MIRAC

Conditions were great tonight — clear, not too windy, and seeing around 0.8” (definitely usable).

Also I updated yesterday’s post with some pictures and a song of the day.

Tonight was the second MIRAC night and the instrument had finished cooling and was nice and cold, so Jarron got to taking data! Unfortunately he had a vignetted pupil again (but differently from last time) but he still got a lot of good throughput and sensitivity measurements.

Meanwhile on the AO side we worked on trying to align our vignetted pupil with the periscope, and also tested the IR camera lens, and took data to calibrate the IR camera lens loop.

Here’s our vignetted AO pupil. [Image description: Two monitors with instrument displays and GUIs. Top left camera display shows the ZWO image. A crescent pupil can be seen. It should look like the telescope pupil.]

This one is a little better. The pupil image looks mostly like the telescope pupil! [Image description: Same monitors, GUIs, and image displays. The top left display shows a mostly-filled pupil image. To the right of it is a bright blob which is the star in the focal plane. Peeking in on the right is a third monitor where you can just see the pyramid pupils — 4 pupil images instead of just 1.]

Also we spent some time with MMTO staff (Ben and Tim) in the first half working on getting the hexapod offsets to point to the rotational center of the telescope. This involved rotating the instrument rotator, measuring the arc on MIRAC, and shifting the hexapod to point there.

By the way, I forgot to mention that we also found ASM contamination yesterday. It was a hard blockage about 160 microns tall. After the contamination removal procedure by Manny, Amali, and Dan, it got down to 60-80 microns, which was workable.

ASM display, after Amali flipped it so that it matches the coordinates when you’re up on the scissor lift facing the ASM. Contamination is at 5:00. [Image description: 3 circles (the ASM at different measurements) with 336 little circles (the actuators) of different colors to represent the actuator currents, heights, and temperatures. A slight raised color table in an almost pie-shaped wedge at 5:00 is the contamination.]

Manny, Dan, and Amali removing contamination in the ASM yesterday.

The best 15 minutes of the day were when, after I woke up early (around 7am), I was reading and grew sleepy again, and realized I was about to get my second sleep! Very important for successfully shifting to a night schedule!

Song of the night: “Oops I Did It Again” by Britney Spears (2000)

MAPS May 2024A Day 1-Night 1: Installation and Alignment

The first two nights of this run are for MIRAC (PI: Leisenring), while the last 4 are for AO (PI: Morzinski). Therefore I decided this was my chance to come up in the morning to see the installation of MAPS. See, usually I try and sleep in on the morning before a MAPS run, to help me switch to a night schedule. But instead today I got up in the morning as usual, headed up to MMT, and was able to observe the installation of the Top Box and ASM with a full MMTO crew as well as Dan and Ruby from MAPS. This is important to me because we’ve talked a lot about the installation procedure and whether it can be made more repeatable, but I hadn’t actually seen the full procedure yet. Now I have a much better picture of the process and thoughts about repeatability.

Installing the Top Box to the Cass port of the MMT.

So here’s what I saw. When the Top Box is installed there are 4 feet on the lift that can be independently adjusted. However, the actual measurement of how parallel the Top Box plate is to the Cass plate is through hand-held measuring tapes. There are 2 pins that help guide the Top Box up. And in the end the plates were flush. But I was wondering whether there could be any skew on one side or another.

Installing the Top Box: Measuring the gap on all sides to make sure it’s going on straight.

The ASM installation is complex. The ASM is mounted to the hexapod. This is done while the former is hanging from the crane and the latter is supported on a bouncy stand — so could these be misaligned? But then the screws are gronked on until the plates are flush, except for a gap covering about 20deg on one side where the ASM plate is warped, of about 4 thou. Then the hexapod is mounted to the hub. It’s behind a flange, but the 2 pins keep it aligned, one of them is diamond shaped to control angle, and then the screws are gronked on until tight so we assume it is flush too.

Measuring the gap over about a 20-degree wedge due to a slightly twisted ASM mounting plate. It appears to be repeatable, plus all the bolts are flush and the rest of the mounting plates are flush with no gap all the way around.

Craning the ASM+Hexapod structure up to mount it to the Hub.

Also Dan and Ruby connected the rack and all our other cables:

Connecting the cables in the elecronics rack on the third floor.

Then tonight was supposed to be a MIRAC night but they had a chiller problem and weren’t cold enough, so instead we decided to try AO.

Except instead it still took over half the night to complete set-up and alignment. So we continue to explore how to improve these procedures.

Even though this is the MAPS run not the MagAO-X run, I’ll stick with the MagAO-X blog rules for this run. Therefore, the best 15 minutes of the day were seeing the ASM mount to the Hexapod and then the whole assembly mount to the Hub. I have to admit I’ve never quite pictured it correctly when we talk about in our off-mountain meetings, so this helped me visualize what’s happening very well!

Song of the Day/Night: “…Baby One More Time” by Britney Spears (1998)