Thursday, September 12, 2013

A Tank-load Of Optics

The remaining optics were installed in the tank today.  First the bridge that holds the fore-optics.

Then the ever-intriguing dichroic - seen here demonstrating how it it transmits light redward of 555 nm & reflects light blueward of that.

Datums were placed all over the optical bench when everything was fully aligned in Durham so we have a huge head-start on getting the optics into their correct positions.

Next up was the Volume Phase Holographic Grating (VPHG) for the red channel.

The VPHGs are used as cross-dispersers to separate the overlapping spectral orders produced by the échelle grating.

Red arm VPHG in position, along with the red fold mirror to the right, seen edge-on.

All of the optics for the red arm were then in place.

After that it was time to mount the two doublets (known as L4 & L5) to complete the fore-optics.

The VPHGs are Ridiculously photogenic!

Off to the other end of the tank to sort out the blue channel...

The optical bench was getting pretty crowded by this stage so the fold mirror had to go in before the VPHG on this side.

Along the way, David - who's been busy getting everything wired up - popped in to attach the housing for the exposure meter.

In this shot you see the fore-optics being messily reflected in the red pupil mirror which still had its protective plastic cover on.

Despite its cover, the collimator mirror had accumulated a fair amount of dust during its life so we blew it clean with dry nitrogen - much better!

Meanwhile, out in the loading bay Luke slaved away on the floor panels.  Trimming off all the edges to make them fit better & then using a heat-gun to slightly melt the sides.  The latter helps to limit the amount of styrofoam shrapnel that gets produced any time you have to handle the panels.  But, apparently, it's also a good way to incrementally toast ones hands to something resembling a sun-burnt crisp!

Over in the electronics room Eddy & David continued to work on the software & other infrastructural issues.

Getting back to setting up the blue channel...  Here's the blue pupil mirror about to be placed on its linear stage.

From this angle we see the blue pupil mirror sandwiched between the turquoise & yellow dichroic & the (still covered) collimator mirror on the right.

Just another shameless gawk at all the beautiful bits of glass...

While Jürgen checks the alignment of the blue channel with respect to the red one - & it looks Good!

With that - it was time to head down the hill & join Tech Ops for a lunch-time braai at the Rec Centre :)

Plenty of chops & wors for the conventional carnivores, & loads of hake for the not-too-rigorous vegetarians in the group.

No better way to celebrate the best day of spring up here so far...

So good was the plan in fact that it lured the likes of Darragh, Ockert, Janus & Brent up from Cape Town!

Eben even gave up his day off to come & join in the festivities...

In an unprecedented turn of events - the food was actually ready At lunch-time!

Big Thank You to Adelaide, Willa, Chris, Vic & everyone else that made the whole thing happen :)

The engineers were quite perplexed as to how so many empty bottles could've appeared before them.  It seems Luke may have had something to do with it?

Even better than the weather & the braai was the cameo appearance by Eben's home-made cannon!


Clearly Team HRS thoroughly underestimated the punch packed by said cannon - it's A Lot louder than one would expect :)

After wrapping up lunch & cannon fire, everyone went back up to SALT to take a look at the Fibre Instrument Feed (FIF) & its auto-guider which Ockert & Janus brought up with them this afternoon.  It really looks great & we can't wait to get it installed in the payload so that we can chase real starlight down the fibres & see what HRS can deliver!

Here's the auto-guider with its fold mirror & various lenses.

Show & tell time!  SAAO/SALT shows Durham the FIF & guider...

Then Durham shows SAAO/SALT what they've been up to!

Later it was off to the hotel for some more cultural immersion therapy for the Durham lads. 

Oom Eben very kindly taught us all a thing or two about the virtues of super-human finger strength.

Fortunately no foreigners were harmed in the process :)

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