ORCHID System Engineering

J. Kent Wallace14 Oct 2010

The Plan

1. Summarize status from last meeting.2. Review status of system priorities.3. Review plans for next few weeks.

System Priorities as of 14 Oct: STATUS

1. Quantify performance of coronagraph tip/tilt system. DONE2. Understand system throughput DONE3. Model impact of ADC on contrast STARTED4. Examine sensitivity of Coronagraph to low-order aberrations

STARTED5. Quantify the current optical alignment and create alignment

plan. STARTED1. Each sub-system individually2. Sub-system co-alignment – Corongraph/CAL: DONE

6. Model phase-induced amplitude errors in the pupil STARTED7. Quantify impact of anti-aliasing filter on CAL NOT DONE

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.

Stellar Flux

AO System Throughput

CAL Science Throughput

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

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

Tip/Tilt Telecon Action ItemsACTION 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

Initial Starting Point

Step 3: Center Quad Cell on StarStep 3 Details

• Signal: Error Signal on Quad Cell

• Actuator: Quad Cell Position

• Algorithm: Zero out Quad Cell x and y tilt

• Responsibility: AMNH

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.

Plan of AttackItem Time People Tasks Goal

Review/Combine Error Budgets

Wed Oct 6PAST DUE

Rich, Mike, Kent, …

Spreadsheets for P3K and CAL.

Preliminary combined performance estimate

Throughput/Emissivity

Thurs Oct 7 Ben, Kent, Mike, GV, …

Measure P1640 bench optics, analyse CAL Data

Validate Budget, Identify optics of concern

ADC Performance Analysis

Thurs Oct 7PAST DUE

Ben, Dimitri, Kent, Mike, Rich,

Model impact of ADC on system. Measure ADC Throughput

Quantify impact of ADC on Contrast