NASA / JPL-Caltech / UA / courtesy of Timothy Reed
The HiRISE focal plane
The HiRISE camera has 14 detectors, lined up on a large focal plane. Ten of the detectors see red wavelengths and form a staggered line that allow HiRISE to capture grayscale images 20,000 pixels across. At the middle of the focal plane are two more pairs of detectors that see blue-green and infrared light, allowing the HiRISE team to show the center 20% of any image swath in color.
At this point in the HiRISE assembly the detector elements are bare but are correctly aligned, set to the same height, and measured so that the locations of the pixels is known to an accuracy of a few microns. Later a metal cover was installed that had spectral filters, sharp-edged rectangular apertures, and stray light baffling.