Naturally Guiding Wavefronts So Phenomenally

Back in Tucson the XWCL team has been very busy hosting some exciting visitors! Teams from the Giant Magellan Telescope Organization and the Arcetri Astrophysical Observatory made their way down south to integrate a natural guide star wavefront sensor prototype (NGWS-P) with HCAT and MagAO-X. To put it simply:

“The Giant Magellan Telescope (GMT) Adaptive Optics (AO) systems feature a single conjugate natural guide star based AO system using the 7 deformable secondaries and a post focal wavefront sensor named NGWS (Natural Guide star Wavefront Sensor). The NGWS has two different channels: one featuring a high spatial sampling pyramid sensor dedicated to the fast frame rate correction of atmospheric turbulence and a second dedicated to the correct phasing of the 7 segments of the GMT telescope.”

Plantet, et al., SPIE Montréal 2022

Essentially, they want to use our GMT simulator (HCAT), and functioning ExAO system (MagAO-X) to validate their prototype wavefront sensing channel (PyWFS) and prototype phasing channel (HDFS).

NGWS-P table and control system set up in MagAO-X lab

I want to impress on everyone reading this blog what a complicated setup this actually is. We are simulating the GMT on the HCAT testbed, feeding the GMT pupil into MagAO-X through a hole in a wall, and feeding the NGWS-P testbed through the MagAO-X eyepiece. That is not easy to do…but we did it!

Lab layout

The team started by using the HCAT lab as a staging area where the teams could integrate the two channels onto the NGWS-P bench. Laird and I were busy inventing new novel optomechanical mounting strategies (AKA zip tying a camera to a ladder) so we could view the focal plane the NGWS-P will be receiving.

Once the dress rehearsal was over, we rolled the NGWS-P into the MagAO-X lab and the team went quickly into alignment.

As the life-long learners we are, when plugging in the NGWS-P cryocooler we unfortunately tripped a circuit breaker and MagAO-X went dark. Duh, duh, duh…Luckily we called our most recent alum Dr. Joseph Long to the rescue!

Don’t worry, it’s all fine. We learned the lesson: if you ever want to force-quit MagAO-X, simply plug in a cryocooler on the same circuit.

The software gurus started to make some quick progress once the whole system was finally in place. Alfio (Arcetri) and William (GMT) were poking away at the MagAO-X DMs using their own wavefront sensor.

Ultimately they were able to close the loop using the NGWS-P modulated PyWFS and the MagAO-X Woofer DM with 30 modes! This was a fantastic first run and there is much more exciting work to be done in our subsequent two runs coming this fall. Looking at you parallel DM.

Sharing this musical experience that the GMT, Arcetri, and Arizona teams got to enjoy at Hotel Congress last Friday evening.

AO4ELT7 Days -1 to 1: Three is Company, Five is a Party!

Bonjour! In the early hours of Saturday, I joined the team in Paris! Fun fact: if you land in Charles de Gaulle Terminal 2E and you want to be picked up by an Uber, do NOT go to the door labeled “Rideshare Pickup.” That would be far too easy. Uber is relegated to “Express Pickup Door 7A”.

Anyways, we shortly boarded our train to Avignon and got a lovely ride through the French countryside.

Paris Gare de Lyon

Apparently in the words of some Roman cardinals, Avignon is one of the most revolting and polluted cities ever seen. Except not really at all…it’s maybe the prettiest. A gorgeous walled-in city surrounding a castle, Avignon is lush and vibrant.

Thanks to the recommendation of Sebastiaan, the team took a fun tour of the Pont Saint-Bénézet, a medieval bridge across the Rhône. Okay it doesn’t exactly go across…it kind of stops in the middle…there was a lot of drama in the Middle Ages.

The one where XWCL goes to the former Roman Empire

Sunday night was the conference registration and welcome reception where we finally joined Laird after his excursion through Portugal. Five is a party! A party with wine and cheese!

Practicing my talk for anyone who will listen

Day 1 of AO4ELT7

The conference hall is in the medieval conclave of the Palais des papes d’Avignon. It’s very unique, and we likely need to elect the next AO pope, but there is definitely not air conditioning.

Order in the court

The conference kicked off with interesting overview talks about the AO systems of each of the ELTs: GMT, TMT, and of course ELT itself. I presented my first conference talk of my grad school career on our up-and-coming extreme AO instrument, GMagAO-X. GMagAO-X is such an exciting project to be on, as a highly likely first light ELT ExAO instrument working in the VISIBLE.

Not a bad way to spend your golden birthday

And as you do at conferences, you network (with your roommates).

Thanks for a lovely day team 🙂

Congratulations Dr. Alex Hedglen!

On Friday, April 14th Alexander Hedglen went from learner to master. Passing his PhD defense, he will go on to work for Northrop Grumman Corp in Rolling Meadows, IL. Alex has been the top optomechanical student for XWCL for the past six years! His projects range from designing telescope simulators to 3″ triplets to crazy mounting schemes for deformable mirrors.

Alex in action: fabricating a part in Chile
Alex in front of open MagAO-X in Las Campanas cleanroom before First Light (2019)

Alex and I started working for Laird back in 2017. I will greatly miss his mentorship and guidance. We have spent long hours in the lab aligning optics, gluing optics, and phasing the GMT segments on HCAT. He has taught me so much about optomechanical engineering and how to make some darn good presentation figures.

Alex and I in “break” room at Las Campanas

We wish Alex, Kateri, Ezra, Clover, and Callie the best of luck on their journey!

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Alex and me working on phasing the High Contrast Adaptive-optics Testbed (HCAT)

Song of the Day

MagAO-X Takes Montréal: Day 2

It’s only day 2 of the SPIE Astronomical Telescopes & Instrumentation Conference and already lots of interesting talks, lunch & learns, and posters are underway.

Dr. Richard Dekany gave an interesting talk on SIGHT, the Palomar 5m telescope LGS AO system, and highlighted the support of our very own Sebastiaan Haffert and Meghan O’Brien on the Optical Differentiation wavefront sensor.

The Equity, Diversity, and Inclusion (EDI) Lunch & Learn brought up interesting points about international differences in approaches to EDI. There are more similar events and networking events throughout the week in room 514!

We supported fellow optical sciences grad student, Kevin Derby, from the UArizona Space Astrophysics Lab during his fantastic talk on pinwheel segmented primary apertures.

Kevin Derby presenting his talk

Since this lab just loves when things are “in-phase”, several of us attended a talk on the phasing of the James Webb Space Telescope by Scott Acton. He had some thoughtful words on his next steps as a scientist, “And that’s how you align the telescope. Now I need another job.”

Scott Acton presenting his talk

On theme with space telescopes, we are finishing the night with UASAL graduate student, Jaren Ashcraft, presenting his poster on the Space Coronagraph Optical Bench – SCoOB.

Jaren presenting his poster

Sorry, I’m not a connoisseur of French music.

“La vie en rose” – Louis Armstrong

Pyramid Schemes & Piston Dreams

For about a year, Laird, Alex H., and I have been putting together the protoype-High Contrast Adaptive Optics Testbed (P-HCAT). P-HCAT sent half of the simulated GMT pupil to the “Holey Mirror” which, as the name suggests, is a mirror with a hole in it.

Holey Mirror

The holey mirror is able to simulate a piston differential with a piezo-controlled mirror sticking through the hole. This light was sent into MagAO-X and the PyWFS was used to sense piston. The next phase of the project was adding post-doc Sebastiaan Haffert’s Holographic Dispersed Fringe Sensor into MagAO-X. This 1″ optic is able to interfere each segment of the GMT pupil with another then disperse them so we can back out the piston differentials. We got some very interesting results we plan on sharing in some upcoming papers!

P-HCAT aligned, not sending light into MagAO-X through the hole in the wall, but rather to a Basler science camera via a fold mirror

The next step is to convert P-HCAT into simply HCAT. This new and improved version will have a concept known as the “parallel DM.” This involves sending the entire GMT pupil onto a reflective 6-sided pyramid, a hexpyramid, which will send the light to 6 separate deformable mirrors. The central segment will pass through a hole in the center of the pyramid.


Manufacturing a hexpyramid with a central hole is no small feat. We are super excited to finally have our hexpyramid in the lab and ready to play with. This week we put it in front of an interferometer to check surface quality. To mount an optic this complex you need to be creative to say the least. See our makeshift mount below. We are happy to note the pyramid is very photogenic – it doesn’t have a bad side!

Hexpyramid mounted in front of interferometer

Piston Control is a fantastic mode of risk reduction for the Giant Magellan Telescope and we are so happy we get to be a part of this effort!