Page 1HMI/AIA Science Meeting – February 13, 2006 HMI Instrument Overview and Calibration Status...

21
Page 1 HMI/AIA Science Meeting – February 13, 2006 HMI Instrument Overview and Calibration Status HMI/AIA Science Meeting February 13, 2006 Jesper Schou HMI Instrument Scientist Stanford University [email protected] (650) 725-9826
  • date post

    22-Dec-2015
  • Category

    Documents

  • view

    218
  • download

    3

Transcript of Page 1HMI/AIA Science Meeting – February 13, 2006 HMI Instrument Overview and Calibration Status...

Page 1 HMI/AIA Science Meeting – February 13, 2006

HMIInstrument Overview

andCalibration Status

HMI/AIA Science MeetingFebruary 13, 2006

Jesper Schou

HMI Instrument Scientist

Stanford University

[email protected]

(650) 725-9826

Page 2 HMI/AIA Science Meeting – February 13, 2006

Outline

• Instrument overview

• Calibration activities

– Overview

– Status

• Conclusion

Page 3 HMI/AIA Science Meeting – February 13, 2006

Instrument Overview

• Optics package

– Telescope section

– Polarization selectors – 3 rotating waveplates for redundancy

– Focus blocks

– Image stabilization system

– 5 element Lyot filter. One element tuned by rotating waveplate

– 2 Michelson interferometers. Tunable with 2 waveplates and 1 polarizer for redundancy

– Reimaging optics and beam distribution system

– Shutters

– 2 functionally identical CCD cameras

• Electronics package

• Cable harness

Page 4 HMI/AIA Science Meeting – February 13, 2006

Image stabilization mirror

CCD fold mirror

CCD fold mirrorFold mirror

¼ Waveplate ½ Waveplates

Telescope lens set Telecentric

lens

Calibration lensesand focus blocks

Front window filter

Relay lens set

Blocking filter

BDS beamsplitter

NarrowbandMichelson

Polarizer

ISS beamsplitterand limb tracker assembly

Tuningwaveplates

Beam control lens

Lyot

WidebandMichelson

CCD

CCD

Shutter assemblies

Aperture stop

Instrument Overview – Optical Path

Optical characteristics:Focal length: 495 cmFocal ratio: f/35.2Final image scale: 24m/arcsec = 0.5”/pixelPrimary to secondary image magnification: 2Focus adjustment aange: 16 steps of 0.4 mm

Filter characteristics:Central wavelength: 613.7 nm FeIFront window rejects 99% solar heat loadFinal filter bandwidth: 0.0076 nmTuning range: 0.069 nmAll polarization states measurable

Page 5 HMI/AIA Science Meeting – February 13, 2006

Observing Scheme

• Observables

– Dopplergrams

– Magnetograms, vector and line of sight

– Others: Intensity, line depth, etc.

• Observables made from filtergrams described by framelists

• Filtergram properties

– Wavelength and polarization state

– Exposure time, camera ID and compression parameters, …

• Framelists

– Fixed list of filtergrams repeated at fixed cadence during normal operations

– Entirely specified in software – highly flexible

Page 6 HMI/AIA Science Meeting – February 13, 2006

Observables Calculation

• Make I, Q, U, V, LCP, RCP– Linear combinations of filtergrams

– Correct for flat field, exposure time and polarization leakage

– Correct for solar rotation and jitter (spatial interpolation)• Sun rotates by 0.3 pixels in 50s, so interpolation necessary

• Fast and accurate algorithm exists

– Correct for acceleration effects (temporal interpolation)• Nyquist criterion almost fulfilled for Doppler and LOS but is violated for vector measurements

• Significant improvement from interpolation and averaging

– Fill gaps• Data loss budget gives missing data in every filtergram, various algorithms exist

• May do nothing for vector field

• Calculate observables– MDI-like and/or least squares for Doppler and LOS

– Fast and/or full inversion for vector field

• Many challenges remain– Calibration, code development, lists of dataproducts etc.

– Community input needed!

Page 7 HMI/AIA Science Meeting – February 13, 2006

Calibration Activities - Overview

• Individual items

• Assemblies

• Assembled instrument

– First Sun test• Instrument partially finished

• Warm, so camera noise is high

– In air test• Almost complete instrument

• Warm, so camera noise is still high

– Vacuum test• Final instrument

• Good environment, but little time

Page 8 HMI/AIA Science Meeting – February 13, 2006

Sun Test Objectives

• Learn how to operate the HMI optics package.

• Learn how to characterize/calibrate the instrument. In some cases, obtain initial calibration parameters.

• Discover gross errors in design or workmanship of the HMI optics package.

• Determine position of focus to set the final shim on the telescope secondary lens.

• Determine position of waveplates in polarization selector to set the final orientation relative to hollow core motor step locations.

• Results of the Sun test will directly feed into the plans and procedures for the formal test and calibration series.

• The Sun test does not provide formal verification of any requirements.

Page 9 HMI/AIA Science Meeting – February 13, 2006

Calibration Status as of Feb. 12, 2006

• White – Not yet finished

– Taken: Data taken but not yet analyzed

– ?????: May not be doable with current configuration (eg. high camera dark current)

• Green – Test done, all is OK

• Yellow – Minor problems

– Incomplete or buggy analysis software.

– Fixable test setup problem or apparent test glitch (eg. clouds)

– Problem is understood and is easy to correct

– Problem is understood and can’t be fixed, but does not impact full science objectives

• Red – Instrument problem potentially impacting science objectives, but

– Not yet fully understood

– Has known likely solution with modest modest schedule and cost impacts

• Black – Fatal problem found

– Problem understood and science objectives can’t be met

– Solution is unknown or has severe cost or schedule impacts

• Surgeon General’s warning: Preliminary results may cause severe upsets!

Page 10 HMI/AIA Science Meeting – February 13, 2006

Calibration Matrix

123456789

1013141617181920212223

24

252628

30

31

32333435363839

A B C F G N O P QTest Group Property First

SunLight Source Status

1 Image quality Distortion Yes Lamp Not yet finished2 Image scale Yes Sun All OK

3a MTF Yes Lamp Minor problem3b MTF Yes Sun Taken Bad4a Focus Yes Lamp Really bad4b Field curvature Yes Lamp4c Focus Yes Sun4d Field curvature Yes Sun Taken*7 Ghost images Yes? All? ?????*8 Scattered light Yes? All? ?????10 CCD and Camera Flat field Yes Lamp11 Linearity Yes Lamp

*12a Quadrant crosstalk No? Lamp ?????*12b Quadrant crosstalk No? Laser ?????13a Contamination Yes Lamp13b Contamination Yes Sun13c Contamination Yes Laser14 Image motions Offset and distortion Yes Lamp15 Filter transmission Wavelength and

spatial dependenceYes Laser + Sun

16 Angular dependence Yes Laser + Sun

17 Stability No? Laser or Sun? ?????19 Throughput Yes Sun

21a Polarization All sorts of stuff Yes Lamp

21b Polarization All sorts of stuff Yes Sun

22 Observables performance

Doppler Yes Sun

23 Line of sight Yes Sun24 Vector Yes Sun

*25 Thermal effects Pointing No? Lamp ?????*26 Focus No? Lamp ?????28 Alignment legs Range and step size Yes Lamp29 Repeatability Yes Lamp

Page 11 HMI/AIA Science Meeting – February 13, 2006

Image Quality

• Distortion– Procedure works, but problems with stimulus telescope illumination. Difficult to do with Sun.

• Image scale– All OK. 0.5025”/pixel

• MTF– Astigmatism seen, but problems with stimulus telescope illumination

– Sun data not yet analyzed

• Focus and field curvature– Right on for lamp. Bad seeing during Sun test

– Field curvature analysis not complete

• Ghost images and scattered light– Difficult to do with high camera noise. May have to be deferred to vacuum test

• Contamination– Still needs to be done

• Image motions– Saw problems with test setup. Probably has been solved

– Some displacements seen with focus blocks

Page 12 HMI/AIA Science Meeting – February 13, 2006

Image focus

Page 13 HMI/AIA Science Meeting – February 13, 2006

Special target continued

Page 14 HMI/AIA Science Meeting – February 13, 2006

Image Wobble

Page 15 HMI/AIA Science Meeting – February 13, 2006

CCD and Camera

• Flat Field

– Details still to be worked out

• Linearity and gain

– Still to be done.

– Difficult due to thermal noise and camera drifts

– Drifts believed due to known problem with this particular camera

• Quadrant crosstalk

– Probably has to await vacuum test due to high thermal noise in air

Page 16 HMI/AIA Science Meeting – February 13, 2006

Filter transmission

• Wavelength and spatial dependence

– Phase maps have been made with laser and Sun

– Test equipment problems for wavelength dependence. Believed fixable.

– Elements will be replaced (decided before this test)

• Angular (as seen from detector) dependence

– Still to be done

• Stability

– Will try, but oven stability in air likely insufficient

• Throughput

– Looks good

– But gain drifts make things difficult

Page 17 HMI/AIA Science Meeting – February 13, 2006

Phase Maps

Page 18 HMI/AIA Science Meeting – February 13, 2006

Polarization

• Some data taken, but much analysis still to be done

• Significant problem found. – Linear polarization into instrument gives circular polarization of up to +/- 0.4!

Page 19 HMI/AIA Science Meeting – February 13, 2006

Observables and Miscellaneous

• Observables

– Still to be done. May wait for some instrument upgrades

• Thermal effects

– Probably not doable in air

• Alignment legs

– Range and step size determined. Meets spec.

– Repeatability. Looks adequate, but more tests planned

Page 20 HMI/AIA Science Meeting – February 13, 2006

Conclusion

• Tests progressing– Some tests done

– Some not

• Some problems found– Some fixed

– Some still need work

– No showstoppers!

• Lots of data to analyze– Over 10000 images so far

– Need people

• Stay tuned!

• Ask not what HMI can do for you!

• Ask what you can do for HMI!

Page 21 HMI/AIA Science Meeting – February 13, 2006

Status - Mechanisms