Tuesday, November 5, 2013

HRS Detector Surgery

The lack of recent updates on the SALT High Resolution Spectrograph (HRS) reflects the fact that our Blogger-in-Chief, Lisa, has been on a well-earned vacation, rather than any inactivity by the HRS team!

HRS Blue: Round 3

The recurring issues with the instability of the HRS blue CCD mount have been tackled (hopefully once and for all) with some radical surgery. David and Paul flew out from Durham to take on the delicate job. The first step was to erect a nifty portable clean tent (kindly loaned by Spaceteq) in the mirror coating chamber so the work could take place in Sutherland. 

 The HRS blue detector being modified inside the clean room tent at SALT. From left, Dave Carter (SAAO), Pieter Swanevelder (SAAO), Paul Clark (Durham CfAI) and Willie Koorts (SAAO).

With Dave (Carter), Willie and Pieter from SAAO looking on, Paul dismantled the dewar leaving just the CCD in there. With the problematic adjustment mechanism fully extracted some nice new kinematic seats were installed along with some G10 insulating washers (to keep the detector side of the adjustment plate from being cooled unnecessarily) and a new cold finger with flexible copper braids. This also meant some quick mods to one or two internal components were necessary which were completed in double quick time courtesy of SALT tech ops - thanks again guys! That same afternoon the CCD was re-mounted and aligned using a travelling digital microscope.  

 Inspecting the business end of the blue detector. From left, Pieter, Dave & Paul

Paul using the nifty digital travelling microscope used to check the positioning and tip/tilt of the CCD.

Paul and Willie working on the blue detector.

Not quite everything went to plan though - the following morning the CCD wasn't quite cold enough so the dewar had to be taken back off again to add some more copper braids to the cold finger. However, a quick & dirty focus run was done to verify that the CCD had come through the process unscathed. 

Post-fix test image of the blue CCD showing good focus

It would have been foolish not to repeat the fix on the red, so David and Paul set about repeating the installation of the kinematic seats on the red (the solid cold finger had previously been installed when the red dewar was overhauled in Durham).

All this was completed by Wed 30 Oct in time for Paul to enjoy a meal & some drinks in town before flying back to Durham. We're not sure how much he actually enjoyed the drinks though, this one a chili flavoured Witblitz that would have made excellent rocket fuel!  

1 comment:

  1. Glad to have you back. Astronomy is so much more fun when somebody writes cool blog posts about it ;)