Thursday, April 28, 2016

Getting the LFC set up

The LFC's horrifically complicated looking optical bench was set up on its pneumatic isolators, atop a thoroughly unpretentious old office desk that was dragged into the HRS electronics room for the occasion.
Getting things back together again after the trip
Some careful cleaning of the optics was in order, to remove dust that had accumulated during the packing, shipping & unpacking processes.  A delicate task, expertly executed.
Cleaning dusty mirrors with alcohol & patience
The array of electronics associated with the comb, much of it custom-built, is a formidable sight as well...  Fortunately it's not usually necessary to directly access the HRS computers (visible in the background), instead we run the spectrograph from the SALT control room, or via a remote desktop connection.
Getting acquainted with the hardware
It's a good kind of chaos - really!
The HRS electronics room after its LFC make-over
& the comb's optical bench is truly a work of art!  The guys usually operate on a much larger optical table in their lab.  But for the sake of making the comb transportable, everything had to be crammed onto a breadboard that would fit on a standard pallet.  As a result, some of the beams require fairly creative steering to negotiate the tight confines of the perspex enclosure, while still having to check in at all the appropriate stations along the way...
Herding laser beams around!
Astronomers are forever scrounging for whatever light they can accumulate, so it's been bizarrely entertaining for us to operate in such a photon rich environment.  For example: to inject the comb light into the little bench-top spectrometer, & avoid saturation, one simply has to deflect part of the beam into the instrument with a piece of paper!  
Swatting light into a spectrometer
Part of the fun is trying to trace the various laser beams as they criss-cross the optical bench, bouncing off of & passing through a multitude of mirrors, beam-splitters, polarisers, lenses & irises, before entering different fibres & detectors (including fast photodiodes & even a mini spectrometer).
Even better than LEGO & Meccano
Tomorrow we'll get more into how the comb works & what all the many bits do...

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