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IQ-R2 » History » Version 2

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

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h1. IQ-R2
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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.
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The idea is to test as many line-item contributions to the PSF budget as possible.  In practice we can probably do the following:
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* Focal plane height varies by <= 30 microns peak-peak.
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* Primary mirror figure / Corrector design / static alignment / flexure contribute <= ??? waves RMS.
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h2. Prerequisites
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* Same as for IQ-R1
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h3. Procedure
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* Use the same science CCD images as for IQ-R1.
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* Reanalyze images but incorporate higher-order Zernike terms in the fit.
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* Subtract out field patterns in coma, astigmatism that could be attributed to misalignment or primary mirror astigmatism.  (Alternatively, extract all azimuthally-symmetric Zernike patterns)
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* Compute wave-front error from all remaining Zernikes.
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h3. Verdict
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Azimuthally WFE is <= ???? microns
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h3. Consequences
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If we fail this test, see if we at least pass IQ-R4.  Assign excess WFE to contingency portion of PSF budget.