Monday, September 9, 2013

The Fibres Are Healthy!

We spent most of the morning waiting for the contractors to get finished before we could do our final clean-up in the HRS enclosure & get on with other things.

Luke, sporting a new red handlebar moustache, worked on producing the earth straps to connect the two outer sections of the tank to the middle bit.

& then one to link the central section of the tank to a ground cable in the electronics room next door.

At one point I walked into the spectrometer room just in time to catch David "ironing" the huge foil bag.  Cheap therapy to deal with an otherwise frustrating day!

Once neatly flattened, the big shiny heap could be folded up & put away.

The most daunting activity of the day was opening up the fibres & checking that they're all ok.

The super-protective packaging for the ends that will attach to the Fibre Instrument Feed (FIF) looked somewhat suspicious, but at least it didn't smell of explosives or have any fuse-like appendages.

Removing the two white protective tubes exposed the 16 fibre ends - neatly covered with little plastic caps over the ends of the brass ferrules.  Here two of the caps had been removed in order to illuminate the fibre ends.

Shortly before the instrument was packed up & shipped here, tiny cover plates with anti-reflection coatings were bonded to the ends of the fibres to protect them & improve their performance.  Not hard to imagine what a fiddly job that must've been!

A white LED flashlight was used to shine light down each mode's star/sky pair.  Very happily, they all lit up as they're supposed to so no damage was done in transit - whew!  The pic below shows light emerging from the Medium Resolution mode fibres & illuminating a white card.  The High Resolution & High Stability fibre pairs looked the same.  We were also pleasantly surprised to find that the double scrambler optics for the HS mode were still sufficiently well aligned to produce spots on the screen!

The Low Resolution mode outputs appear on small 45° mirrors attached to the slit-mask & shutter assembly.  Seeing spots light up on those mirrors confirmed that the LR fibres are in good health as well :)  The slit-mask & shutter assembly is one of the most complex parts of the instrument, containing lenses, mirrors, an electro-formed slit-mask for mode selection, a calibration fibre, mechanical stages, at least one spring & loads of small screws...

Here you can see the mode selection mask with the MR slits at the top, HR at the bottom & HS in the middle with a small 45° mirror for the simultaneous ThAr calibration option to the right of the HS slits.  The little mirrors for the LR fibres are just about visible below the slit-mask.

At one point the childish ones among us decided it was a good idea to decorate our face masks.  Luke went with a very fine handlebar moustache while I opted for the hippo-with-inappropriately-spaced-nostrils look.

Thanks to Ant for the photos & to Jürgen for providing a set of ears.

Tomrorow we plan to connect up the camera dewars so we promise to be more serious...

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