MagAO-X 2020A Stay At Home Day 29: AO for Exoplanets

In the days of MagAO-Classic, I would write daily blog posts 3-5 times per week. By the time we got to Day 29 in the run I would be so exhausted I was grateful for anyone to write blog posts. Now the tables have turned and here I am, belatedly showing up on the blog after a month ~~on the mountain~~ at home!

This Andean cat has been snuggling with me all day. — Photo from today on Day 29 of the Classical MagAO run. Here I am at the Clay telescope at LCO on a brilliantly sunny day, supervising the ASM being driven up on the Isuzu truck. (Or maybe being driven down.) I have lured one of the local fuzzy fauna for some snuggles. Looks like I found an Andean Cat. Yes, all is fine here at MagAO-Classic. [Image Description: A woman in glasses holds a cute cat, both lit up by interior light. The background shows a sunlit Chilean mountain scene. Magic of Zoom backgrounds.]

OK so what have I actually been working on? Well, the above picture is actually relevant.

Adaptive Optics (AO) for Exoplanets can be done in various different ways. One difference is the type of Deformable Mirror (DM) you use to control the wavefront. You can use an Adaptive Secondary Mirror (ASM) for better sensitivity to planets that are brighter in infrared (heat) wavelengths. Or you can use a Micro-Electro-Mechanical Systems (MEMS) for better sensitivity to planets that are reflecting the light of their stars (like our Moon reflects our Sun).

MagAO-Classic uses an ASM, and while it has been successful with both infrared planets with Clio and visible-light planets with VisAO, its sensitivity was limited in the visible. Therefore MagAO-eXtreme uses a MEMS, for more precise wavefront control that allows for better sensitivity to reflected-light planets.

I have worked with both MEMS and ASM DMs. In ancient times (pre-Classical) I characterized many iterations of MEMS DMs for the Gemini Planet Imager (GPI), including holding the positions and monitoring what they do over time:

Most of them were really good! This is important especially for MEMS DMs since they don't have capacitive sensors like on an ASM, so it's good that the actuators behave so stably and repeatably! — Stability plot of the displacement (measured with a 100-pm-accuracy interferometer) of all the actuators on MEMS device number W10#X in the Laboratory for Adaptive Optics at UCSC. Perfect actuators would be a flat horizontal line in this plot. [Image description: A line plot of actuator displacement in nanometers phase (aka. nm wavefront, rather than nm surface) vs time step since beginning the experiment. Each actuator has its own line, although only a few are called out in color. Most of the actuators were around 0 displacement. A few actuators started out too low. Over several minutes, a few actuators drifted to lower positions, which they are not supposed to do.]

MagAO-X has a similar but more modern MEMS, and my expertise has come in handy. Now in the post-classical world I’m PI of the “MAPS” instrument (MMT AO exoPlanet characterization System). MAPS is using an ASM that we are building ourselves at Arizona. We are in the lab-testing phase and Amali Vaz (click to read her award-winning blog posts) is running similar tests of actuator stability on the MAPS ASM:

Since ASMs have capacitive sensors, we can do these tests electrically without an interferometer, unlike for the MEMS above. — Stability plot of the counts measured at the capacitive sensors vs time. The initial jump is a command by the AO operator. A perfect actuator in this plot would be exactly horizontal after that point. [Image description: A line plot of actuator position measurememnt from the capacitive sensor (capsens) vs. time in seconds. Amali has added a small offset to each actuator to shift them vertically on the plot so that they can be distinguished. Most of the actuators are fairly flat, but a few drift slightly lower over time. This is preliminary work and was done with almost no gap and with the thicker test shell, so this is not concerning at this point. Just interesting to start to do these kinds of tests, and to compare to the MEMS.]

The MAPS ASM project was initially led by the original MagAO-C/Clio PI, Phil Hinz. He has moved to a new job to lead the Laboratory for Adaptive Optics (where the above MEMS work was done) and I am now PI of both MAPS and Clio. So this project has been a way back into DM and actuator characterization. Let’s look at some more pictures.

Mounting a perfectly fine shell was just as nerve-wracking as dismounting a glycol-glued on shell. — At the start of stay-at-home, we were still able to go into the lab with a whole group of people. Here are 4 people mounting the thin shell on the reference body of the MAPS ASM. From left to right: Grant West, Oli Durney, Manny Montoya, Emily Mailhot. Oli and Manny are eyeballing the gap, and checking whether the clocking is correct. Grant is keeping an eye on the scale, to detect when the magnets start to lift the shell. Emily is controlling the actuator coil currents, and keeping an eye on the shell. [Image description: In a clean room, 4 people are wearing lab coats, gloves, hair nets, and face masks. An optomechanical structure in the center is the MAPS ASM, looking down as if the telescope is parked at zenith and the primary mirror is below. The thin shell of glass rests on a cart with a scale on a lift, and is being slowly raised until contact with the reference body. The reference body is a clear-ish thick glass circle. Above it is the cold plate, similar thickness and copper-colored but aluminum. The actuators are clamped to the cold plate and their cables are black and run up above the cold plate. The electronics consist of 6 daughterboards and 1 motherboard and are at the top of the unit. The four people are focused intently on the work they are doing to mount the thin shell onto the reference body. Once mounted, the thin shell + reference body + cold plate + actuators + actuator cables + electronics = ASM.]

Amali is THE expert in ASM operation. — Now that we have come under more strict stay-at-home orders, we are operating the ASM remotely. Here is a Zoom grab from today when Amali was filling Phil in on what she had been measuring and learning. [Image description: A screen grab of a Zoom meeting where the main focus is the web gui being run on Manny’s computer. The web gui has two ASM maps, the one on the left shows the position as measured by the capsens, while the one on the right shows the coil currents as commanded by the AO operator.]

The song of the day is a Classic (that can be pushed to the eXtreme) that I first learned in high school band, Malagueña. I present a study of some of my favorite versions. First the Drum & Bugle Core version, representing ancient history:

Then the classical guitar version, a Classic:

Finally, a special treat, Fuego Malagueña by Esteban featuring Teresa Joy, is the eXtreme version: