Friday, August 14, 2009

Paddling around between M2 & M5

Having vanquished the virus that was doing the rounds, the team dived back into the M5 alignment process!

The mirror we'd been using on the back of M2 (to get the alignment telescope set up in tip & tilt) wasn't flat enough so we now have a high quality mirror for the job. Since we need to be able to slide it in between M2 & M5 & move it in & out of position over the hole in M2, the mirror was set within a flat paddle.

The mirror protrudes 0.5 mm below the paddle so that the alignment telescope could be set with the mirror resting perfectly level on the back of M2. But the paddle needs to hold the mirror above the hole in M2 & still keep it parallel to the back of M2 so jacking screws with incredibly fine pitch threads (250 microns per turn!) were used to lift the paddle & get the mirror perpendicular to the alignment telescope's optical axis again.

A temporary mount for the alignment telescope was arranged on the aluminium ring of the NRS simulator so that it could peer down just inside the birdcage to see the mirror resting flat on the back of M2.

Once the jacked up mirror had been levelled again, it was time to haul out the nail varnish (Charlie: Ruby Red #018 - thanks Sam!) & lock the 3 screws in position.

Although Our Captain appeared to quite enjoy painting the screws, he's clearly more at home back behind a telescope...

True to astronomical form though, the human at the eyepiece was soon replaced with a small CCD camera, allowing the determination of centroids & offsets to be done more accurately by Francois' software.

A familiar scene from a new perspective - the god's eye view!

While all the fuss gets made about the IQ side of things, don't forget about Peter & the gang still doing battle with that scary looking spectrograph next door!

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