Third Quarter 1997

The contract for fabrication of the slit mirrors was awarded to Max Levy Autograph, Inc. To ensure the sharpest possible slit edge for low scatter, and good reflection performance for slit viewing, coatings are applied to calcium fluoride substrates using lithography. Phase II of the cryostat fabrication was awarded to Hughes Tools, Inc. Phase II includes all the components required for the first cryogenic tests (support truss, liquid nitrogen can, cold shields etc.). Final drafting of the cryo-mechanics for Phase III (the spectrograph box) and Phase IV (the fore-optics and slit-viewer) is proceeding very well but slower than predicted.

Fabrication of the vacuum jacket (Phase I) is taking Hughes Tools longer than expected. Part of the delay is due to an e-beam welding problem at the sub-contractors. This has since been fixed. Delivery is now scheduled for October. Fabrication of optical components at OFR (lenses and windows) and SSG (off-axis parabola) is also proceeding slower than hoped due to late delivery of material substrates. A 0.8-5.5~micron anti-reflection coating on a full-size ZnS witness sample was cryogenically cycled in our filter test dewar several times without incident. This Thin Film Labs coating will be applied to our ZnS lenses.

Lab testing of the array controller commenced in September. First read out of the 1024x1024 bare multiplexer, assembled in the lab test dewar, is expected in October.

Of the 12 InSb wafers so far processed for the PAIDAI Project at SBRC (from which SpeX will get its arrays), four have yielded "science grade" wafers. (Better than reported last quarter.) Twelve more wafers are still in processing. Most parts successfully hybridized at SBRC are found to suffer from one or two photon emitting defects (PEDs), which make the hybrids unuseable. Although the origin of the PEDs is not yet understood, SBRC are now confident that PEDs can be removed by a combination of laser beam ablation and chemical etch of the glowing pixel. This process removes the electrical short from InSb pixel to detector ground by removing InSb in a 3x3 pixel area centered on a PED. PAIDAI is scheduled to hybridize its first two parts in November.

A proposal requesting $97k in funding was submitted to NSF for adding a high-speed low-resolution spectroscopy mode to SpeX. This mode is primarily intended for spectrally resolved occultation observations, and high sensitivity wide-band observations of small solar system bodies, cool stars and brown dwarfs. The major hardware components required to implement the new mode comprise a prism, an additional DSP board, and an UltraSPARC computer.