Alignment

These procedures assume that you have completed the System Startup and Daily Startup. In other words, CACAO is configured, you have a PSF on camtip, and you are modulating.

System Pupil Alignment

This procedure will align the pupils on dmtweeter, dmncpc, and camwfs. Things to remember:

ttmpupil is used to align the system pupil on dmtweeter. We use the actuators on dmtweeter as the reference (the F-Test).

ttmpupil moves the image of M1 in every pupil-plane inside MagAO-X, including dmwoofer, dmtweeter, on the modulator, camwfs, fwpupil (and the very nearby dmncpc), fwlyot, and as reimaged on camsci1.

We use ttmperi to align the pupil in the coronagraph using dmncpc actuators as a reference (the J-test).

However, ttmperi moves the pupil image for all of the lower bench. Thus it is important to remember that you are also moving the pupil on camwfs with ttmperi during the J-Test, which can affect loop stability.

The camera lens, which consists of stagecamlensx and stagecamlensy, moves the pupils on camwfs. The primary purpose of this is to register the dmtweeter actuators with the camwfs pixels.

However, on-sky we use the position of the camwfs pupils to control ttmpupil to keep the system pupil aligned as the K-mirror rotates. This only works under the assumption that the actuators are aligned to the pixels first.

In the lab moving ttmpupil to fix camwfs pupil positions mis-registers the actuators w.r.t. the camwfs pixels. So the Pupil Tracking Loop must NOT be used in lab mode.

Decide on your beam splitter

All of the alignment uses cameras downstream of the stagebs science/WFS beamsplitter, and changing beamsplitter causes shifts in both the pupil and focal plane. Thus a change of beamsplitter will invalidate your alignment and require you to repeat these steps.

Decide whether you’re using H-alpha / IR or 65-35 first, and configure stagebs.

Pupil Alignment

This is the main pupil alignment procedure which should be followed after starting up, or after switching beam splitters. The individual F-Test, J-Test, and camwfs alignments are performed when needed as part of this, and are described below.

hit t in the camtip rtimv display to show the target cross

use the keypad on Pupil Alignment GUI to move woofer so the PSF is on the cross

check that camwfs EM gain is 1, then open shutter

Continue using move woofer to get roughly even illumination of the pupils. This can include adjusting focus.

put fwfpm in flat

If using camflowfs:

put camflowfs in default ROI, and press t to show the target cross on its display.

Open the camflowfs shutter. If you do not see a PSF on camflowfs:

If you have already completed the alignment successfully, but are now switching beamsplitters: use the drop-down box to select the new beamsplitter.

Warning

Do not use the drop-down unless you are sure that you need to. This is a relative move equivalent to hitting the arrow keys many times. It is not an absolute move to a setpoint. Do not use this to troubleshoot!

camsci1 has a wider FOV. Make sure fwscind is not in pupil, move fwfpm to open, then use camsci1 to find the spot.

If you can see it on camsci, use pico sci-x to move the spot to roughly centered on camsci1, then return to camflowfs.

If you do not see the spot on either camflowfs or camsci1 then something is wrong. Check all filter wheel and stage positions, ensure shutters are responding and open.

On Pupil Alignment Gui use the pico sci-x buttons to move the PSF left and right to center on the target

See above warning regarding using the drop-down selection for changing beamsplitters.

Use the arrow buttons to move, changing the scale for finer control

The PSF should be centered on the target in the camflowfs display

If not using camflowfs (i.e. using camsci1 to align):

Set camsci1 to the full ROI

Take a dark and then open the camsci1 shutter

Ensure fwscind is not in pupil, move fwfpm to open, then find the spot in the camsci1 image

If you cannot see a PSF, something is wrong upstream. Check upstream filters and stage positions, shutters, etc.

On Pupil Alignment Gui use the pico sci-x buttons to approximately center the PSF on camsci1

Next set woofer offloading to 2 modes

Close the loop on tip/tilt only

low gain is fine. Multiplication Coefficient should be 1.0

If using camflowfs:

Now select move ttm on lower left of Pupil Guide Gui

With the loop closed:

move up and down with the arrows to center on the target on camflowfs in y.

also clean up any remaining x alignment with pico sci-x.

Keeping the loop closed, you can now start Auto Alignment of the ttmpupil and cameralensx/cameralensy devices

Monitor the camwfs pupil position to ensure it does not run away

Monitor “Pupil Tracking Loop” and “Actuator Alignment Loop” deltas.

Once the loops have converged (“Pupil Tracking Loop” and “Actuator Alignment Loop” deltas less than 0.05 in the lab) stop the Auto Alignment loop.

In the lab the Pupil Tracking Loop should turn off when you stop the Auto Alignment loop.

On sky the Pupil Tracking Loop should remain on when you stop the Auto Alignment loop.

Adjust flux on camwfs using flipwfsf and fwtelsim, and set camwfs EM gain.

you may need to reset protection

take a camwfs dark

now close the loop, up to ~200 modes

bring up t/t, then focus, then higher order modes block by block

Once 10 modes are closed, increase Woofer Offloading to 10 modes

Now repeat the Auto Alignment steps above with the loop closed

Once the Auto Alignment has converged again, stop it.

Now perform the J-test (below). Once the J-test is complete, you need to re-align the camwfs pupils using the camera lens by hand. Do not run Auto Alignment at this step.

You should now be able to close all modes.

Once all modes are closed, you may need to adjust camera lens position with the directional buttons on the Alignment GUI. Do not use Auto Alignment for this.

Tweeter Pupil Alignment (F-Test)

This does not need to be done if you have performed the Auto Alignment, however it is usually good to check it to make sure the automatic loop has converged properly.

Note

If you modify the F-Test by actuating ttmpupil, you will need to re-do both the J-Test and the camwfs pupil alignments.

To manually align the pupil on the tweeter, we perform the F-Test (which is now actually an R).

fwpupil to open (in Coronagraph Alignment GUI)
fwfpm to open
fwlyot to open
fwscind to pupil (in camsci1Ctrl)
fwsci1 to z
configure camsci1 so that you can see the pupil without saturating.
Move stagesci1 to preset fpm.
If necessary, use the “Loop Zero” buttons to remove any leftover AO corrections.

Now put the test pattern on the tweeter with Pupil Alignment GUI for dmtweeter. Press the set test under Tweeter

Next, use the “TTM Pupil” section to align the pupil on the tweeter using the arrow keypad. The following figure demonstrates what a good alignment looks like.

When done, use the Tweeter zero test button on the Alignment GUI.

Decide on your beam splitter

The J-test and later alignment takes place downstream of the stagebs science/WFS beamsplitter, so a change of beamsplitter will invalidate your alignment and require you to repeat those steps.

Decide whether you’re using H-alpha / IR or 65-35 first, and configure stagebs.

NCPC Pupil Alignment (J-Test)

To align the pupil on dmncpc, we perform the J-Test.

Note

ttmperi moves the pupil on the lower bench, including on camwfs. This means performing the J-Test in closed-loop can cause instability. You will need to manually adjust pupil position on camwfs with the camera lens.

Note

The F-Test (above) also changes the J-Test. The J-Test should only be performed after the F-Test (or Auto Alignment) is complete.

The system should be configured for the F-test above. Next,

Move stagesci1 to preset jtest-telsim.
Put the test pattern on the dmncpc` with the “Set Test” button next to “NCPC” on the Pupil Alignment GUI.
Press the set test under NCPC

Next, use the arrow buttons below TTM Peri to align the pupil on the NCPC DM. The following figure demonstrates what a good alignment looks like.

Clear the J-test with the “zero test” button on the Pupil Alignment GUI
Return stagesci1 to the fpm position

Post-J-test Pyramid Pupil Alignment

If you have performed the Auto Alignment this only needs to be done after performing the J-test.

Check the offsets under Pupil Tracking Loop in the Pupil Alignment GUI
Using the directional buttons under the “Camera Lens” section to move the pupil images on camwfs until the x and y displacements are less than 0.05 pixels in the lab (0.1 pixels on-sky).

Warning

The “pupil tracking loop” is not used in lab mode, only on-sky.

Focal Plane and Coronagraph Alignment

Bump-Mask Alignment

From the camsci1 gui, set

fwscind to pupil

stagesci1 to jtest-telsim

With the camsci1 shutter open, take a new dark. This will serve as the reference for alignment.

In the coronagraph alignment GUI: set fwpupil to bump-mask.

The camsci1 viewer will show the difference image, making it easier to align with the (now obscured) spider arms of the pupil.

Use the “Pupil Plane” directional buttons on the coronagraph alignment GUI to align the mask to the pupil.

Once the bump mask is aligned, change fwscind back to whatever you had before switching to pupil imaging mode.

Remember to close the shutter on camsci1 and take a new dark.

Focus Diversity Phase Retrieval (FDPR)

To further improve PSF quality, run focus diversity phase retrieval (FDPR) on camsci1 to derive a new non-common-path correction DM shape.

There are multiple ways to configure the algorithm (see Focus Diversity Phase Retrieval (and correction)), but we most commonly use the CH4-875 filter in camsci1 to compute a correction applied to dmncpc.

Configure fwsci1 with the narrow-band methane filter CH4-875

Place stagesci1 at preset fpm

Define a ROI centered on the core of the PSF of size 369x369

Adjust exposure times as needed to have plenty (25000–30000) of counts in the peak of the PSF

Close the shutter and take new darks. (Then open the shutter.)

Open a terminal on ICC

export OPENBLAS_NUM_THREADS=1 to avoid bogging down ICC with the process (TODO: make this automatic)

Run the FDPR process with: fdpr2_close_loop fdpr2_dmncpc_camsci1_CH4

Save the flat with dm_save_flat ncpc -d fdpr

On dmncpc zero all channels, then select the new flat in the drop down and apply it.