In August, Phase IVa of the cryostat fabrication (the fore-optics mounts and image rotator assembly) was awarded to Earth, Air and Space (EAS). The remainder of the mechanical fabrication (slit-viewer, dichroic turret, prism and grating mounts, and instrument mounting box) are scheduled for fabrication in the machine shop here at the IfA. Also during August, Optics For Research delivered the AR coated lenses and windows, and Thin Film Labs delivered the dichroic beam-splitters for SpeX and NSFCAM.
Building upon experience gained with the prototype controller fabrication of slightly modified array controllers for SpeX was started during the Third Quarter. To enable higher speed read out for the newly funded high-speed spectroscopy mode a second DSP board was added to the VME64 control computer together with a second optical fiber channel, one for each DSP board, linking the cryostat mounted electronics to the computer. These modifications increased the (full array) speed from 3Hz to 10Hz.
PAIDAI members met at the Raytheon Infrared Center of Excellence (RIRCoE - formerly SBRC) in Santa Barbara on July 17 to review progress. The cold tests of the first four arrays at RIRCoE were reviewed and the order of testing at NOAO, following PED removal, was decided. By the end of September these arrays had been characterized by Al Fowler at NOAO. All four are four quadrant devices and the best, SCA47672, is one of the best Aladdin 2 arrays yet produced. SCA47672 is cosmetically good with a median dark current of about 0.2 electrons/sec and a readnoise of 40 electrons RMS. The next four arrays should be fully characterized by November. The final six 1024x1024 InSb parts will be hybridized onto Aladdin 3 readouts and the 10 week process is expected to begin in November. The first six 512x512 are currently in hybridization and should be out of the foundry and ready for testing by the end of the year. SpeX will use a 512x512 array in its slit-viewer/imager.
Photos for this quarter:
|Cryostat-mounted electronics rackmount containing clock/bias, ADC, pre-amp and fiber channel boards|
|Big Dog computer runs the spectrogaph array. The rackmount contains a single-board SPARC computer, two DSP boards, and two fiber boards with fiber optic links to the cryostat-mounted electronics|
|Guide Dog computer runs the slit-viewer/imager array. The rackmount shown contains a a single-board SPARC computer, one DSP board, one fiber board, and a GPS board|
|Cold structure on fork lift truck.|
|Cold structure being moved into vacuum jacket|
|Cold structure bolted into vacuum jacket|
|Cryostat with cover removed on the lift/tilt table|
|Flexure testingof the cryostat on the lift/tilt table|
|Closed-cycle cooler and thermal connection to actively cooled radiation shield|
|Cryostat and cold structure showing LN2 can bolted to spectrograph box, cold mounting structure and support trusses. The active shield and vacuum jacket covers are removed.|
|Active shield. A view of the cryostat showing the actively cooled radiation shield which surrounds the LN2 cooled cold structure|
|First cooldown showing LN2 can fill and closed-cycle cooler plumbing|