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Stephen Kent, 07/19/2012 03:01 PM


IQ-R2

Optical prescription, fabrication errors, alignment errors, flexure, and CCD non-planarity contribute no more than ?? waves RMS (or ? FHWM) to images taken at best-focus position [DECam TO-2 (see Table 2 for budget), TO-4] To be tested over full HA/Dec range of Survey.

The idea is to test as many line-item contributions to the PSF budget as possible. In practice we can probably do the following:
  • Focal plane height varies by <= 30 microns peak-peak.
  • Primary mirror figure / Corrector design / static alignment / flexure contribute <= ??? waves RMS.

Prerequisites

  • Same as for IQ-R1

Procedure

  • Use the same science CCD images as for IQ-R1.
  • Reanalyze images but incorporate higher-order Zernike terms in the fit.
  • Subtract out field patterns in coma, astigmatism that could be attributed to misalignment or primary mirror astigmatism. (Alternatively, extract all azimuthally-symmetric Zernike patterns)
  • Compute wave-front error from all remaining Zernikes.

Verdict

Azimuthally WFE is <= ???? microns

Consequences

If we fail this test, see if we at least pass IQ-R4. Assign excess WFE to contingency portion of PSF budget.