Kyle Van Gorkom – Page 2 – Extreme Wavefront Control Lab

MagAO-X 2019B Unpacking Day 5: Airy Disks

Today we got our first proper airy disk at LCO!

This morning, Laird and Alex rotated the K-mirror to a more optimal position and re-aligned the rest of the optical train. I switched out a board in an ALPAO driver to one that lets us power the NCPC (non-common-path-corrector) DM remotely, which saves us many hypothetical trips to and from the Nasmyth platform. Jared did…well, a lot of everything.

Alignment specialists, aligning.
The innards of an ALPAO driver

One tool that has proven useful in the alignment process is an “F”- and “X”-shaped pattern on the 2K deformable mirror (previously featured here), which we can view in high resolution on our LOWFS (low-order wavefront sensing) camera.

After Alex and Laird were happy with the alignment, I drove out (most of?) the remaining system aberrations with the “eye doctor” script, which attempts to find the combination of Zernike modes on the deformable mirrors that maximizes our Strehl.

Alignment F-Test on the 2-Kilo DM, as imaged on the pupil viewer
Instrument PSFs on the pyramid tip (left) and science camera #1 (right), post alignment and eye doctor. We have airy disks!

Reinforcements in the form of Joseph Long arrived this afternoon, although fumigation delayed his luggage in Santiago and left him (temporarily, we hope) dispossessed of his worldly goods (and a few supplies for MagAO-X). The MagAO-C team joined us after dinner for a tour of MagAO-X.

The united MagAO-C and MagAO-X teams walk up to the halfway house after dinner.
The tour.

After the tour completed and the crowds dispersed, Alex and Laird reinstalled the panels, shielding the instrument from prying eyes (and unwanted particles—of both the massive and massless variety). Jared installed the blower (the large white tube entering the instrument table from the left) to supply the optics with a soothing breeze.

After spying a guanaco in the far distance earlier in the week, I finally encountered two up close yesterday. They were surprisingly…pungent.

A guanaco who may be Gary. Yes, I recorded vertically.

As always, we stopped to watch the sunset.

Another beautiful LCO sunset, another disappointing lack of green flashes

For the song of the day, I present “Stairway to the Stars” by the Queen of Jazz herself, Ella Fitzgerald.

MagAO-X 2019B Unpacking Day 2: MagAO-X Does Bongs

Unpacking Day 2 marks the 3rd day of MagAO-X unpacking activities, which only makes sense if you’re a computer scientist or you just try not to think about it too much.

Alex and Laird began the day by removing the teflon bars that had been installed in front of particularly expensive optics for protection during shipping.

Laird and Alex hard at work in the clean room

Meanwhile, Jared pressure-tested the electronics rack coolant system while I set up the AO Operator Computer.

The PI at work
Mega Desk II: Not Quite Mega Yet (But It Will Be Once We Get That Missing Monitor Bracket)

We filled the instrument coolant lines with glycol and hooked the table to air, giving MagAO-X its first breath and drink at LCO.

The instrument table’s first breath of mountain air

Fresh glycol adds a much-needed splash of color to the instrument.

After passing its pressure test, the electronics rack coolant system joined in on the activities. Things got a little out of hand when Jared fashioned a makeshift bong and started passing out mixed drinks (glycol and distilled water — not recommended for human consumption).

Jared and Alex fill the liquid-liquid exchanger with the titular bong
The glycol forest in the underbelly of the electronics rack

And, most importantly, the goats made another appearance.

Alex visited with goats during an afternoon stroll.

I present the MagAO-X song of the day: “Always Something There to Remind Me” by Naked Eyes (related to the most recent MagAO-C song by its year of release—a tenuous but legal connection) .

We’ve closed the loop* on MagAO-X!

* with two DMs! But not at the same time…yet.

Late last week, after painstakingly recabling and aligning the BMC 2K following its relocation to the MagAO-X instrument, we closed the loop at 3.6kHz with 2040 actuators. See Jared’s video below:

MagAO-X Closed Loop 3.6 kHz

What exactly are we looking at in this video?

On the far left is the image from our pyramid wavefront sensor. It’s tricky to interpret, but the four pupil images are a bit (but not exactly) like a 2-axis knife-edge test, with the key difference that aberrant rays are refracted into the different pupil images rather than simply blocked or passed. Through the magic of linear algebra (and lots of calibration), each frame from the wavefront sensor is converted into a map of voltages to apply to the DM to cancel this wavefront error.

The DM commands can be found along the bottom row of windows in the video. It’s split across multiple channels, but the important one is the image on the far right: each pixel is a command we’re sending to an individual actuator on the DM. With the loop open, we’re just creating simulated atmospheric turbulence. With the loop closed, it’s the same simulated turbulence plus the correction computed from the wavefront sensor.

And, finally, on the upper right is the “science” PSF, doing its thing. (That last image on the desktop—the pixelated one in the top middle—is the command sent to the ALPAO DM, but it’s not doing anything here other than holding a flat shape.)

Olivier gestures at a computer monitor while Jared looks on — Jared and Olivier debate the finer points of *cacao.*

Before we could close the loop, the 2K had to be aligned, which isn’t a trivial task when you’ve just dropped it into the middle of a rather complicated optical system and expect the beam to be centered on the DM to better than one actuator (which have a pitch of 400 microns). Enter Laird and Alex, experts on all things alignment. To aid in their efforts, we placed a pattern on the DM that could be seen both on the wavefront sensor and by eye in the beam reflected by the DM.

Laird and (the mostly obscured) Alex wrangle DM cables while aligning.
The DM alignment pattern seen in the reflected beam.
The alignment PSF: more fun than an airy disk?

This isn’t the first time we’ve closed the loop on MagAO-X. A month ago, we closed the loop on the low-order ALPAO DM-97 (the woofer). We have video evidence of that too:

MagAO-X woofer, closed loop at 2 kHz

And finally, to procrastinate studying for finals a few moments more, here’s my half-micron (peak to valley) entry into the ongoing MagAO-X logo contest, imprinted on the 2K and measured on our Zygo interferometer: