JimO: the question is, what OTHER space instruments were built equally flawed?

NASA to clear up comet hunter's blurry vision
Software will sharpen images from Boulder-built craft bound for collision

http://rockymountainnews.com/drmn/state/article/0,1299,DRMN_21_3844441,00.html

By Jim Erickson, Rocky Mountain News
June 10, 2005

NASA officials said Thursday they have found a fix for the blurry vision <snip>

Shortly after Deep Impact was launched Jan. 12, engineers found a focusing problem in the spacecraft's main camera-telescope, the High Resolution Instrument.

The problem has been traced to a mirror used when the HRI was tested at Ball, the space agency said. While flat at room temperatures, the mirror unexpectedly developed a slight curvature during testing at ultra-cold temperatures. Ball engineers didn't detect the curvature at the time.

"It was a mirror used in the test setup, not part of the instrument itself," said Harold Reitsema, director of program development at Ball. "Because of the curvature in the test mirror, we set the focus (on the HRI) slightly incorrectly."