First Quarter 1998

In January, a space model of SpeX was put on the telescope to check for interference with the telescope yoke as the telescope was moved around the sky. No problems were expected with the instrument in its observing position (on the telescope optical axis), but it was necessary to establish which of the four stowed positions on the IRTF's Multiple Instrument Mount (MIM) is most suitable. The only suitable stowed position was found to be the East MIM location, and this is also best for telescope balance and day crew access to the instrument.

Following further testing of the prototype array controller using a bare multiplexer, an Aladdin 2 array from the Subaru/IRCS was successfully used to take images in the lab test dewar for the first time on February 23. The initial results from these tests were presented by Onaka et al. at the Kona SPIE conference in March, together with separate papers on the array controller (Onaka et al.) and the SpeX project (Rayner et al.). Fabrication of the two array controllers for SpeX will now begin. (SpeX will use two arrays.)

Inspection of the lenses at Optics for Research showed that some of the thicknesses were out of specification. This required changes to the optical design to accommodate the slight change in focus at the slit and at the two detectors. A LiF lens was also damaged during final polishing and is being re-made. AR coating of the lenses will be delayed until this work is completed. Delivery is expected next quarter.

In March, Phase III of the cryostat fabrication (the spectrograph - light-tight spectrograph box, optical mounts, grating turret, slit wheel and focus stage) was awarded to Hughes Tools, Inc. Fabrication of Phase II at Hughes Tools is proceeding slower than hoped. Final drafting of the drawings for Phase IV of the cryostat fabrication (mechanical components of the fore-optics and slit-viewer) is continuing.

By the end of March six PAIDAI arrays were out of the foundry (hybridize, epoxy wick, thin and wire bond) and ready for cold testing at SBRC. Cold testing at SBRC has been delayed by dewar problems. PAIDAI has produced a large number of science grade InSb die and additional funds are being sought to make more arrays.

Photos for this quarter:

Space model of SpeX on the IRTF.
J.Rayner, helping the day crew, moves the telescope which the SpeX Model.
Aladdin 2 bare multiplexer image from prototype array controller.