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ORCHID System Engineering J. Kent Wallace 14 Oct 2010
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The Plan 1.Summarize status from last meeting. 2.Review status of system priorities. 3.Review plans for next few weeks.
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System Priorities as of 14 Oct: STATUS 1.Quantify performance of coronagraph tip/tilt system. DONE 2.Understand system throughput DONE 3.Model impact of ADC on contrast STARTED 4.Examine sensitivity of Coronagraph to low-order aberrations STARTED 5.Quantify the current optical alignment and create alignment plan. STARTED 1.Each sub-system individually 2.Sub-system co-alignment – Corongraph/CAL: DONE 6.Model phase-induced amplitude errors in the pupil STARTED 7.Quantify impact of anti-aliasing filter on CAL NOT DONE
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Throughput Created photometry spreadsheet that quantifies stellar photons and system throughput based upon surface-by-surface reflectivity. Processed some on sky data as measured by the CAL system. Conclusion: Up to CAL, there is reasonable agreement between expected and measured photon fluxes.
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Stellar Flux
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AO System Throughput
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CAL Science Throughput
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Total Frame DN vs Frame No. Average H-band Flux = 5 * 609,300 DN per sample * 6.3 e- per DN / (0.6 e- per photon) Average H-band Flux = 3.2 10^7 photons/sec Average DN = 609,300 per 5 Hz Sample
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Theoretical CAL Flux Theoretical CAL Flux = Stellar Flux * AO Throughput * CAL Throughput Theoretical CAL Flux = 1.39 10^9 photons per sec* 0.785* 0.059 Theoretical CAL Flux = 6.44 10^7 photons per sec Experimental Average H-band Flux = 3.2 10^7 photons/sec Experimental = 0.5 Theoretical
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Tip/Tilt Telecon Action Items ACTION ITEMS: Ben is to provide raw data on the quad cells reasonably soon. DONE P3K to verify that its software supports P1640 Coronagraph PZT tip/tilt offloads to the P3K tip/tilt system. This capability will be needed by P1640 on sky. DONE Ben to provide software upgrades to allow recording of quad cell tip/tilt data. DONE Rick, Kent, Gautam and Mike to document co-alignment of the FPM/Quad Cell/Pinhole DONE Kent and Gautam to clarify, operationally, who is the person to determine that the system is ready to observe. DONE
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Initial Starting Point
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Step 3: Center Quad Cell on Star Step 3 Details Signal: Error Signal on Quad Cell Actuator: Quad Cell Position Algorithm: Zero out Quad Cell x and y tilt Responsibility: AMNH
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Next Steps: Status Integrate sub-system error budgets STATUS: NOT DONE Come to consensus on a common performance metric (contrast curve definition) STATUS: STARTED Initiate detailed system performance modeling STATUS: STARTED Dimtri is building up the simulation, so we gathering information to include in this Coordinate a plan of attack for regularly addressing highest priority tasks.
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Plan of Attack ItemTimePeopleTasksGoal Review/Combine Error Budgets Wed Oct 6 PAST DUE Rich, Mike, Kent, … Spreadsheets for P3K and CAL. Preliminary combined performance estimate Throughput/ Emissivity Thurs Oct 7Ben, Kent, Mike, GV, … Measure P1640 bench optics, analyse CAL Data Validate Budget, Identify optics of concern ADC Performance Analysis Thurs Oct 7 PAST DUE Ben, Dimitri, Kent, Mike, Rich, Model impact of ADC on system. Measure ADC Throughput Quantify impact of ADC on Contrast
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