Performance Results

1. Performance Results Jesper Schou HMI Instrument Scientist Stanford University

2. Overview • Overall assessment • Key results by subject • Conclusion

3. Overall Assessment/Executive Summary Good to go!

4. Image Quality • Field of view/vignetting • Does not meet spec due to Lyot vignetting • Best estimate is 1990”+/-10” versus 2000” CPS and 2012” IPD requirement • However, it is larger than the solar image at maximum (1944”) and thus acceptable • Image scale • About 0.505”/pixel – Well within spec • Camera co-alignment • Excellent. 7 pixels at center and +/-3 to edge versus 20 requirement • Some thermal effects • Focus • Best focus around position 9 (of 1-16) • Camera difference is insignificant at 0.1-0.2 steps • Field curvature: < 0.3 steps center to edge • Focus gradient: Variations exceed measurement accuracy, but are acceptable • Thermal dependence: Significant, as expected • Have thermal control • Used to correct for window degradation

5. Image Quality - Focus Combined instrument and stimulus telescope HMI only

6. Image Quality – Focus Changes with Window Temperature To 25C To 30C To 20C

7. Image Quality • Absolute roll • Data still to be reduced. • Final calibration on orbit, as planned • Similar to calibrations done for MDI • Distortion • Larger than desired, but repeatable, so not a problem • No significant thermal effects • MTF • Looks very good after installation of repolished window. Recent Strehl ratio is 0.84! • Measurement to correct for stimulus telescope still to be done. • Optical ghost images • Nothing significant • Scattered light • Somewhat larger than desired (no spec in IPD) • 10-20% will be scattered light in dark sunspots • This can be mostly calibrated out and does not affect primary science objectives • Contamination • Some contamination as well as other defects seen. Nothing problematic.

8. Image Quality 1X 16X

9. Distortion

10. Contamination – The Movie

11. Contamination - Stills Lyot elements E4/E5 Lyot element E2 Blocker Telecentric lens CCD Stimulus telescope

12. Image Motions • Waveplates • Some motions seen for polarization selectors - mostly taken out by ISS • Residual likely due to polarization of input light • Significant wavelength selector motions (up to 0.4 pixels vs. 0.1 requirement) • Not taken out by ISS • Wavelength selector shifts can’t be explained by geometric effects • Motion in y only and inconsistent amplitude - presumably due to test setup problem • If instrumental in origin we are confident that we can calibrate them out • No distortions seen for any waveplates • Focus blocks • Large motions seen due to incorrect spec - All taken out by ISS. Uses fraction of range. • Thermally induced • Duty cycles implemented by cycling heaters on/off on integer seconds • Slower than thermal timescale • Exceeds spec for uncorrected motions for some duty cycle durations • If needed, using finer granularity in flight software is estimated to be a simple modification • Simple deadband control method plus external driving causes large temperature swings • Various options being considered • Grounds based correction, operational constraints or flight software change

13. Filter Transmission • Wavelength and spatial dependence – tunable elements • Excellent phase (wavelength) variations and contrasts • Center wavelength of untuned part is off by 0.022A versus 0.1A requirement • FWHM is 76.5mA versus 76mA+/-10mA • Tuning range (FSR of tunable Lyot element) is 693mA within req. of 680mA+/-10% • Angular dependence • Nothing bad seen • Thermal effects • Good temperature compensation • Front window fringes move with temperature - Not a significant problem

14. Filter Transmission • Drift • Michelsons drift slowly in wavelength. Also seen with MDI. Not a problem • Turn-on transients • Small Doppler velocity perturbations after instrument has been idle • Deferred to on-orbit. • As planned • Seen and characterized with MDI • May imply operational constraints. • Throughput • Better than conservative CDR estimate. • Noise much less than 25m/s requirement within the +/-6km/s dynamic range • Also good in the presence of 3kG field dynamic range (25m/s does not apply)

15. Filter Transmission

16. Filter Transmission – Resulting Errors

17. Filter Transmission – Resulting Errors With Field

18. Polarization • Overall polarization • Measurements consistent within spec (1% systematic errors in Q,U,V) • Roll angle not measured for earlier runs – must estimate • See plot of average demodulated by one run • Focus dependence • Insignificant • Wavelength dependence • Insignificant • Temperature – box • Significant effect due temperature dependence of birefringence • Need temperatures to calibrate – see plot • Temperature – front window • Some effects seen • Some modeling or test with spare window may be required • Remaining differences (better than spec) being worked • Some likely due to temperature dependencies • Some likely due to second order effects etc.

19. I Q U V I Q U V Polarization – Error Matrix INPUT OUTPUT

20. Polarization – Temperature Dependence

21. Observables • Seeing and GSE problems limit usefulness • Palo Alto is a poor site • Heliostat design is inadequate • Fires got in the way • These are, of course, the kind of problems going into space avoids! • Please excuse artifacts in movie

22. Observables – The Movie

23. Observables – The Movie Part II MDI

24. ISS and Alignment Legs • ISS • Performance meets spec • Spacecraft input may exceed original spec • HGA antenna stepping causes pointing disturbances • Software fix has been implemented by spacecraft and HMI • No antenna stepping while taking images • Alignment legs • Range exceeds spec (+/- about 500” vs. 200” requirement) • Step size smaller than required (0.32” versus 2” requirement)

25. CCDs and Cameras • Dark level • Nothing significant • Mechanism noise • Nothing detected • Flat field • Preliminary flatfields done. Nothing unusual seen • Small scale variations appears repeatable at the 0.1% requirement level • Final flat fields will have to be done on-orbit • Better precision • Temporal variations (eg. Radiation damage) • Algorithms exist and have been applied to MDI data • As planned • Linearity and gain • Look good • Full well • >200000e- versus IPD spec of 128000e- • Quadrant and camera crosstalk • Nothing detected

26. Conclusion • No significant problems with hardware • Some items are out of spec • Eg. Field of view • Mechanism induced image motions • May be an artifact, but if instrumental we are confident that we can correct in ground based processing • Some items deferred to on-orbit • Final roll angle, flat field, turn-on transients • We knew from the outset that these had to be done on-orbit • Have experience from MDI • We are confident that these can be calibrated on-orbit • Some items have other issues • Thermal control • See significant (larger than spec) motions on relevant timescales • Various options being considered – ground corrections, operational constraints, flight software • Polarization calibration is highly temperature dependent – can be calibrated • Some modeling may be required • Scattered light • Larger than we like, but acceptable

27. Conclusion – Executive Summary Good to go!