Wide Field and Planetary Camera 2 Instrument Handbook for Cycle 14
5.3 Wavefront Quality
The conclusion of the extensive optical testing in Thermal Vacuum was that the cameras are well corrected to within the specifications. The dominant problem was a small difference in focus between the four cameras (Krist and Burrows 1995). The actuated fold mirrors and pick-off mirror mechanism performed flawlessly in correcting residual coma aberrations in the image, and enabled the on-orbit alignment procedures. Using out-of-focus images, a very accurate alignment of the cameras was accomplished. A side product was that the aberrations in each camera were measured (Krist and Burrows, Applied Optics, 1995). The results are given in Table 5.2. These values were used in generating the simulated PSFs given in Model PSFs. The WF3 wavefront error is higher than that of the other chips because it is the most out-of-focus relative to the PC (which is assumed to be in focus). It is the equivalent of about 10 microns of breathing out-of-focus.
Aberration PC1 WF2 WF3 WF4
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