Category Archives: Hardware

MagAO Commissioning Day 9 – Nighttime Edition: Incorporating Clio

Today was a busy day, and we began splitting MagAO’ers into day and night crew.  See Derek’s awesome post for the bulk of the day’s tasks: aligning the CRO and ASM.

The next major happening was mounting Clio to the NAS.  Even though we didn’t play the theme from Top Gun as we did it (sorry Phil!), it was an exciting moment.  This is the first time our infrared camera officially met our optical camera and our AO system!  They are together at the telescope at last!

Clio, VisAO, W-unit, Nas, ASM, Clay: So happy together!

Here’s how it happened:

Removing Clio from the support cart with the crane — under PI Phil's watchful care

Attaching Clio to the NAS ring — under Phil's watchful care

Clio at the Nas, flanked by Phil and Katie

Left: Phil and Clio instrument. Right: Clio electronics rack and Phil.

Phil, Katie, and Laird then aligned Clio’s cold pupil stops to the ASM.

Heave-ho: Shimming Clio to align the cold stops

How's it look, Phil?

LCO crew were busy as always, making everything work smoothly for the run.  Here, Mauricio brings up LN2 to fill Clio’s dewar, and Pato optimizes the PID loop that rotates the Nas while the telescope tracks and slews:

Mauricio brings up LN2 to the Nas platform to fill the Clio dewar

Pato feels for vibrations as he optimizes the PID loop tracking and slewing the Nas rotater

 

Quotes:
Alfio: “What is this mirror cover?”
Laird: “Oh you’re so cute Alfio.”

Phil:  “I don’t lean on Clio.”

Phil:  “Used to be, we only had 1 actuator.”

Povilas: “Can 14 mm be considered a shim? That’s more like a structural member.”

Simone has a key to Galileo's house.

Katie: “Hey Jared, how’s it going with the CRO?”
Jared: “I dunno. It’s all in Italian.”

Jared: “The number of Illuminati asking me questions is daunting.” (That would be Simone Esposito himself, as well as suspected members Laird, Phil, and Armando — see our paper for more info.)

 

Armandino

Jared: “I’m pretty sure I would throw myself off the catwalk if Armando thought it would help.

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Turno

Manny and Richard are on their way home. Clio2 survived shipping, and is ready for MagAO to send it some flat wavefronts.

The electronics rack for Clio2 fits, and doesn't vibrate (too much).

The last thing the guys did was train the LCO staff on how to keep Clio cold.

Manny Montoya briefing the LCO crew on Clio2 operations.

Some hands on training. The blue gloves keep your fingertips attached to your fingers - LN2 is cold!

The next MagAO detachment leaves Tucson today. We’re on our way.

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Clio2 Gets The Freeze

After shipping, unpacking, and verifying that everything still works, the last step was for Manny and Richard to cool Clio2 down. Then they took some pictures.

Manny celebrates after taking a good, low-noise, pupil image. He and Richard just successfully cooled Clio2 down to operating temperature and confirmed that the detector works.

Since it works in the IR, basically detecting the heat of planets and brown dwarfs, Clio2 is kept very cold. This is because a blackbody at room-temperature emits most of its energy at a wavelength of about 10 μm, according to Wien’s law. A lot of flux from the tail of the distribution is also emitted at near-IR wavelengths of 1–5 μm. Therefore, for IR astronomy, it is important to keep the telescope and the instrument cold, to avoid this excess thermal flux, which shows up as noise in our images (you’ll hear us call it “sky” or “background”).

To make this work, Clio is contained in a dewar, which is a kind of vacuum flask (a.k.a. Thermos) — an insulated canister that keeps cryogenic material at very cold temperatures. Clio2 has a nested-dewar design with an outer and an inner vessel. The cryogen we use is liquid nitrogen, which has a boiling point of 77 K stp. We also lower the pressure in the inner dewar, using a vacuum pump, in order to solidify the nitrogen (55 K). A blackbody of 77 K emits most of its radiation at ~38 μm, and a blackbody of 55 K emits most of its radiation at ~53 μm. These wavelengths are well beyond what we care about when hunting planets.

In case you ever find yourself in charge at LCO, the cooldown steps and instructions for refilling cryogens are also posted in the Clio user manual.

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It Begins: Clio Unpacking

The invasion of LCO has begun. A scouting party consisting of Manny Montoya and Richard Sosa arrived this weekend and began unpacking the Clio2 infrared camera. Here is their report:

Day 1: “Clio was unpacked yesterday morning and we confirmed that nothing was damaged in shipping. Clio was put on the vacuum pump and we confirmed that we had not lost vacuum. The electronics rack and other stuff was unpacked and accounted for. The electronics rack cabling was tied down a little more securely since this was not possible before it left Tucson, and we also confirmed that nothing had broken during shipping. One thing that did get a little tweaked was the monitor and keyboard support to rack were bent. We straightened them out and put nuts behind it to make it more secure. The rack was then plugged into Clio and the computer, temp. controller, motor control were all tested, checking both the physical conection and through the runclio command on the gui. We then plugged into the network, it was not working so Emilio helped us with the vlan connection.”

Manny checking out Clio2 in the cleanroom.

Day2: “This morning we took the ring up to the telescope and confirmed that it fit on the MagAO NAS. We also checked the flower box to window measurements, we still have to check these with Clio to confirm there are no collision points, but the ring did fit. After the ring was confirmed to fit, we took it back down and put Clio2 and its cart together. This afternoon we are moving everthing into the clean room to prepare for cooling of Clio2 tommorow.”

Richard checks that the Clio2 mounting ring fits. It's nice when we drill the holes in the right place the first time.

Proof that this is actually happening at LCO. Clay and Baade behind Manny as he escorts the ring back down to the clean room.

Clio2 and the mounting ring being mated.

Clio2 all ready to go. Just needs a cooldown.

Stay tuned for more MagAO action.

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Clio has arrived

Clio has arrived!  The shipment containing the boxes for the instrument, ring, and rack was delivered to the cleanroom unpacking area at LCO earlier today:

Clio arrives

Clio arrives - thanks to Marc Leroy for the photo

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Tracking Clio

Our IR science camera, Clio, has arrived in Chile and is in transit to LCO.  Here’s a pic from last month in Arizona: 

Clio and friends

Clio flanked by Manny Montoya (left) and Mitch Nash (right), in the lab at Steward last month.

Stay tuned – more updates about Clio coming soon.

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WFS Readnoise

While the NAS was mounted on the telescope we took a quick set of readnoise measurements with the CCD39. Here are the results. The only major caveat is that the telescope was not tracking, so we didn’t test whether the drives have any impact. Otherwise, this is the most realistic set of RON measurements we have taken to date. We are very happy with the results, especially the 156kHz 3.8 electrons. This number essentially sets the limit to how faint our guide star can be, so keeping it low is important.

Pixel Rate (kHz) Frame Rate (fps) RON (e-)
156 80 3.8
400 197 5.8
900 893 8.4
2500 1053 10.2

Note: these are determined using the actual gains from Scimeasure, rather than assuming 0.5. This can cause as much as an 8% difference.

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Interlude: Installing new cold stops and a J-band filter into Clio2

Meanwhile, back in Tucson… We interrupt the NAS Fitcheck program to bring you this update on the Clio2 infrared camera.

After the Pre-Ship Review for Clio2 in Amsterdam in July, we have been completing preparations to receive diffraction-limited near-IR to thermal-IR photons from MagAO. Yesterday and today we installed the new J-band filter, and the cold pupil stops sized for Magellan. This was done in a CAAO lab at Steward Observatory in Tucson, where Clio2 is undergoing its final testing before shipment.

Cold pupil stops: Clio2 used to be “Clio” and was installed on the MMT telescope in Arizona. The MMT, like Magellan, is a 6.5-m telescope, but the Magellan secondary is 0.85m while the MMT secondary is 0.7m. Therefore, because the pupil is different, we needed two new cold stops for Clio2 on Magellan. A cold stop is a cryogenically-cooled metal mask located at an image of the telescope pupil, and its purpose is to block stray light (heat sources in the dome cause a lot of background thermal light) from contaminating the infrared image. Here is a picture of the pupil wheel with the new cold stops:

Clockwise from Phil's hand: 3-hole non-redundant aperture mask (NRM); 6-hole non-redundant aperture mask (NRM); Wide-camera cold stop (home); M-band apodized-phase plate (APP); L'-band apodized-phase plate (APP); Narrow-camera cold stop.

We also added a new J-band filter, taking out the old 3-5um Janostech filter from filter-wheel 1:

Clockwise from the red arrow: J (new), Blocked (for darks), Open (home), MKO M', Barr M, Direct vision prism, 3.1um, Barr L'.

We updated the Clio2 user manual at http://zero.as.arizona.edu/groups/clio2usermanual/ so that we can repeat this in Chile if need be.  Note the tools required: Most of the wrenches were found in a standard set of Allen keys, except for the 0.035” driver which is a special size.

Tools required for changing Clio2 filters: Phillips/flat head, 0.035, 5/64, 3/32, 7/64, and 9/64 inch Allen keys.

It took about 3 hours to take it apart and insert the new filter and pupil stops, including finding new spacers, etc.  It took about 1 hour to put it all back together.

 

T.J. Rodigas (foreground) and Andy Skemer (background) helped take Clio2 apart.

The box labeled 3 and 4 contains filter wheels 1 and 2. The box labeled 2 contains the cold pupil stops. We disconnected the wires and unscrewed the bellows (those keep the shafts straight at cryo temperatures) to access the filter and pupil wheels.

The same view as the previous image, with the filter and pupil wheels removed.

Two by two, hands of blue

Opening the pupil box to put in the new cold stops, and also Phil put in a new home switch. (Otherwise we could have just inserted the new cold stops through the port and not had to open it all the way.)

Oli Durney putting Clio2 back together

 

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CCD Cooling Build

Jason finished assembling our new CCD (and shutter) cooling system in the mirror lab yesterday. After several tries, and finally replacing the threaded cap that wouldn’t hold pressure, the system passed a pressure and operational test. It’s on its way to Pasadena, and from there to Chile.

Here Jason is installing the drain valve on the tank outlet.

These are our CCD cold plates, and the famous shutter, with coolant flowing through them.

Just after pressurizing the system.

And after about 10 minutes, with the pump running.

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Filter Update

I have updated our VisAO filter curves to now include the effects of 3 reflections from Aluminum mirrors (important because Al has a feature at 0.8 microns), the Clio dichroic, the AR coated surfaces of the VisAO Optics, and the protected silver gimbal mirror in the VisAO camera. Most of these are small losses, but 3 Al reflections are fairly costly at only ~90% reflectance each. I have also convolved the resultant curves with the HST/STIS Vega spectrum to give the approximate photon flux in each filter from a 0 magnitude star. The only major thing not included in these calculations is the reflectance of the beam splitter, since it will vary depending on AO system setup.

The VisAO Camera filter curves

The VisAO Camera filter curves.

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Our Mirror is a Mirror

On March 10, 2011 the MagAO secondary shell had its frontside successfully aluminized at the University of Arizona, Steward Observatory coating facility in Tucson by Richard Sosa and Gary Rosenbaum. This also took a lot of hard work by Jason Lewis and Victor Gasho.

Magellan ASM side view

The side of our freshly aluminized 850 mm diameter adaptive secondary for MagAO. This shell is just 1.5mm thick with 585 magnets glued on the back.

The Magellan ASM

The newly coated front of the secondary.

Victor and the ASM

Project Manager Victor Gasho reflected in the secondary

Laird and the ASM

A relieved Principal Investigator Laird Close reflected in the secondary.

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White light PSF

After completing our work with the laser, we switched to a white light source to test the camera’s performance in broad band filters. This is our PSF in the Sloan Digitial Sky Survey (SDSS) i’ filter (a nice set of filter curves is here), which passes light from roughly 0.684 to 0.840 microns. A theoretical Airy pattern is shown for comparison, and Laird calculates our Strehl ratio as 94% – meaning that our optics are very good.

i' PSF

The Magellan VisAO i' PSF

This image is taken without the ADC in the beam. In the laboratory, without the dispersion of an atmosphere to act against it, the residual chromatism of the ADC would slightly degrade the image quality of a broadband source (see Kopon 2008). This “zenith spike” effect was predicted and does not manifest itself on-sky.

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It’s Alive!

After a very intense couple of weeks, we have built up the nearly complete VisAO camera in the Magellan AO Lab at Steward Observatory. The images below show the hardware mounted on the board. Missing is the wavefront sensor (WFS) hardware, which is waiting for us in Florence, Italy.

Top down view of VisAO

The VisAO camera in the Magellan AO lab.

VisAO camera from the right side

A side view of the VisAO camera

The numbers label specific components:
1: The input lens, in a temporary holder (the permanent one is awaiting us in Italy too).
2: The ADC mount, containing an early prototype of the custom 2-triplet ADC designed by Derek Kopon.
3: The beamsplitter wheel, a.k.a. filter wheel 1. This allows us to select how much and what wavelength of light is sent to the WFS and to our science camera.
4: The Wollaston prism on its lift. This splits the beam in 2 to enable our simultaneous differential imaging (SDI) mode.
5: Our tip-tilt gimbal mirror. This is a temporary solution, which we hope to replace with a high speed tip-tilt mirror.
6: Filter wheel 2. This wheel contains our main photometric filters, currently: SDSS r’, i’, z’, and a filter which passes wavelengths longer than 950nm.
7: Baffle tube. We plan to add a pickoff occulting spot here, to feed a tip-tilt and Strehl sensing camera which will mount on the platform over the tube. These are planned future improvements.
8: Filter wheel 3: This wheel will contain our SDI filters (2 filters in one cell) and in the future our occulting spots (to block the bright central star light).
9: The shutter. You can see our vibration isolation system (the rubber grommets). These are the only place that the shutter mount contacts the rest of the camera.
10: The CCD47. The liquid cooling attachment, another temporary device, keeps our dark current low.

Everything is now under software control in our lab, and it has even started to feel more like a telescope control room when we are taking data. The image below was taken last week.

VisAO 1 micron PSF

The VisAO point spread function (PSF) at 1 micron.

We took this image at 1064 nm (the main IR line of a double YAG laser) through the input lens, the ADC, using the 50/50 beam splitter, and the SDSS z’ filter. The Wollaston was down, and we first focused the system using our motorized focus stage. This is a log stretch, in which I count 15 Airy rings. The cross (one bright line and one dark line) are very small detector artifacts that are only visible due to the log scale.

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The filter wheels in action

Here is a demo of our filter wheel assembly (designed by Kevin Brutlag and assembled by Jason Lewis) spinning under the control of the AO Supervisor software.

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