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SBRC 256 x 256 InSb Preliminary Evaluation Results (1Sep92)
(from ETS, NOAO Newsletter No. 31, 1 September 1992)

The IR program has been evaluating the SBRC InSb array to determine its
suitability for use in the Cryogenic Optical Bench and other future IR
instruments. The preliminary tests indicate that this array is very
good, and we have proceeded to procure one for use at Kitt Peak in
COB.

The dark currents we measured on our array were in the 2 electrons/sec
range using median statistics to reduce the effect of very hot pixels
on the calculation. There was somewhat of a bright edge around the
array similar to the 58 x 62 InSb array, but we have not tried baking to
see if that reduces or eliminates this effect. At these very low dark
current levels it could be due to LED effects in the shift registers
and current sources as the high QE of InSb makes it more sensitive to
these effects.

The noise we measured was substantially less than quoted by SBRC, but
we are using the reset-read-read procedure developed here for reading
out IR arrays. I have not yet used our low-noise read technique on this
array, but it has been reported to me that it does work. Using the
reset-read-read we have gotten 25-30 electrons read noise, and the
University of Rochester group has gotten as low as 12 electrons using
the low-noise read technique.

We are continuing our evaluation and optimization, but the preliminary
results were encouraging enough to procure a science grade device for
the Cryogenic Optical Bench. Evaluation of that array at the telescope
in COB will be proceeding next semester.

Al Fowler

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