The Imaging device of the High Resolution Channel is a single 1024 × 1024 pixel CCD optimized for the near UV. This CCD, manufactured by Scientific Imaging Technologies (SITe), is based on the STIS 1024 × 1024 21 micron CCD (figure), a three phases back-illuminated device, but it differs in the backside processing. The near UV optimization was processed at the Steward Observatory by Mike Lesser using the Steward CAT-B process. The 1024 rows are divided into two groups of 512 rows. There is an output amplifier at each corner of the device, at each end of the two output registers. Thus the array can be divided into quadrants 512×512 to maximize data transfer. The serial register has one pixel for each column in the image area, plus 16 extra pixels at each end for a total of 1056 pixels. Any or all the four amplifiers may be selected for the readout. The normal operating mode will be the readout through a single ampifier, which jas been selected for the lowest read noise, yielding an overall read time of 30 secsonds.
The HRC utilizes the BALL STIS CCD controller which features a 16 bit ADC. The CCD is mounted in a vacuum enclosure which is a STIS mechanical and thermal design. The single fused-silica dewar window is oriented normal to the chief ray to minimize lateral color . The CCD plane is tilted to match the best image surface. The angle between the window and the CCD is 30.8 degree. (see figure)