Sun Test Overview

1
Sun Test Overview
2
Sun Test Overview Interdependencies

• At least three tests are prerequisites for other
  tests
• Focus
• Can use either Sun or lamp
• Needed to reduce length of other tests
• Not needed for many tests due to bad seeing or
  spatial averaging
• Wavelength dependence
• Either Sun or laser can be used
• Needed to set tuning positions
• Not needed for lamp or polarization tests
• Polarization calibration
• Lamp or Sun can be used
• Needed to make observing sequences. Especially
  LOS.
• Note that none of these are dependent on each
  other
• Others are needed before analysis can be
  completed

3
Sun Test Overview Other prerequisites

• There are a number of other tests we need to
  perform before starting
• Determine exposure times
• Lamp
• Sun
• Laser
• Test various targets
• Determine spatial power and quality of each
• Alignments
• Stim tel
• Laser
• Heliostat
• Existing focus test procedure may be used for
  these

4
Sun Test Go/no go criteria

• Several types of criteria
• Prerequisites done See separate charts
• Equipment available and properly configured
• Laser and wavemeter working
• PCU properly configured
• Targets available/installed
• Sunlight
• Some require long stretches of clear skies
• Others can use shorter stretches and/or light
  clouds
• STOLs working
• Procedural issues resolved
• See overview chart and individual tests for
  details

5
Sun Test Pass/fail criteria

• This is not an acceptance test!
• However, we are looking for gross errors
• Note that in many cases all we need is
  characterization NOT pass/fail
• Two levels
• Do we have the required data?
• If no pass/fail then we only need to know when we
  have data of sufficient quality
• Have we analyzed the data?
• If pass/fail needed or if test is prerequisite
  for other tests we need short turn around
• Analysis software for prerequisites is ready
• Preliminary results and decisions will be part of
  calibration meetings
• In case of gross errors high level decisions
  needed
• Abort Sun test and fix problem
• Continue with other parts of test

6
Sun Test Priorities

• Several competing criteria for priority
• Make good use of sunlight
• May not get that many days
• Do prerequisites first
• Equipment constraints
• Dont want to fire up laser too often
• Dont want to change PCU configuration too often
• Allow efficient development and testing of STOL
  procedures
• Easy ones first
• Test various types
• Maximize time to develop and run analysis
  procedures
• Data of marginal quality (eg. clouds) may still
  allow for some testing
• May need data from other instruments
• MDI under our control, but keyhole
• May like to have data from ground based. GONG,
  SOLIS, ASP,
• Near real time flexibility will be required to be
  efficient!
• With this in mind

7
Sun Test Attack plan

• Get STOLs for prerequisites ready before test
  starts
• Focus done. Wavelength dependence and PCU both
  well defined
• Run all relevant STOLs we have as soon as we can
• Can check for proper functioning may do
  abbreviated versions to save time
• Gives sample data for analysis code development
• POR Dont do extensive real time debugging
• Run STOLs even if ideal source not available
• With luck we can have prerequisites done on day
  one!
• Does depend on PCU operational
• Does depend on Sun shining or laser working
• Dont use laser on day one
• Probably takes too long to get set up
• Can use other sources for initial tests
• But do get it to work soon, especially if
  forecast calls for solid overcast
• Plan further tests depending on weather, people
  and equipment availability
• Try to get prerequisites done as soon as possible
• Do weekly and daily planning

8
Data Processing

• Will use MDI data system (DSDS) for storing data
• Should easily be able to handle data volume
• Will use HMI data system (DRMS) for metadata
• Still in beta test, but alternatives exist
• A few basic utilities will be available
• Data query, selection and export
• Image reconstruction (remove cross)
• Etc.
• Analysis will be done with ad-hoc code
• Mostly IDL
• Observables code may have to be optimized to
  reduce computing time
• Codes for prerequisites exist

9
Image Quality Focus

• Purpose
• Determine the nominal focus position
• Requirements
• Need to take images for other tests near optimal
  focus. Also needed to set secondary shim.
• Description
• Determine spatial power as a function of focus
  setting. Fit model to determine ideal focus.
• Test configuration
• Stimulus telescope with lamp and desired
  target(s) (dots). Sun may also be used to
  illuminate target.
• Also do with direct sunlight from heliostat.
• Test plan
• Take images at all 16 focus positions.
• Data analysis
• For each focus position determine the amount of
  spatial power. Fit parabola to three highest
  points to determine best focus.
• For the Sun it may be possible to use the
  sharpness of the limb.
• Codes are ready.
• Procedure
• STOL status Exists.
• Shop order status Does not exist
• The test timeline 16 images of 10s or 3 minutes.
  Little setup required.

10
Image Quality Distortion

• Purpose
• Determine the amount of optical distortion.
• Requirements
• 0.001 (0.02 pixels) based on Korzennik et al.
  (204) 0.01pixels desirable.
• Description
• Determine parameters in distortion model by
  offpointing instrument using alignment legs.
• Test configuration
• Stimulus telescope with lamp and desired
  target(s) (dots). Sun may also be used to
  illuminate target.
• Test plan
• At each of 5x5 leg offsets, take images at a few
  positions around the nominal focus.
• Data analysis
• For each focus position determine the offsets
  between each pair of images for a grid of points
  in the images.
• Fit distortion model to the measured offsets.
• Codes are ready.
• Procedure
• STOL status Does not exist
• Shop order status Does not exist
• The test timeline Each series is 25 offsets
  times 5 focus positions for a total of 125
  images. At 10s per images this will take 20
  minutes. Needs to be run for a few targets plus
  setup so a few hours.
• No particular personnel required.

11
Mechanism induced images motions and distortions

• Purpose
• Determine the image motions and distortions
  introduced by rotating the optics in the hollow
  core motors.
• Requirements
• CPS gives 0.1 (0.2 pixels). IPD 4.3 gives a goal
  of 0.1 pixels.
• Description
• Determine offsets by taking images of fixed
  target at various HCM rotation angles.
• Test configuration
• Stimulus telescope with lamp and desired
  target(s) (dots). Sun may also be used to
  illuminate target.
• Test plan
• For each of 7 HCMs and each of 10 or so angles,
  take images at a few positions around the nominal
  focus.
• Data analysis
• At each focus position determine the offsets
  between each pair of images for a grid of points
  in the images..
• Code is ready.
• Procedure
• STOL status Does not exist
• Shop order status Does not exist
• The test timeline About 100 images. At 10s per
  images this will take 20 minutes. Needs to be run
  for a few targets plus setup so a few hours.
• No particular personnel required.

12
Image Quality Field curvature

• Purpose
• Determine the amount of field curvature.
• Requirements
• The change of focus as a function of image
  position should be a fraction of a focus step.
• Description
• Determine spatial power as a function of focus
  setting, leg offset and image position. Fit
  model.
• Test configuration
• Stimulus telescope with lamp and desired
  target(s) (dots). Sun may also be used to
  illuminate target.
• Also do with sunlight.
• Test plan
• Same as for distortion. Also use sun focus
  series.
• Data analysis
• At each leg position and image position fit mode
  power as a function of focus position to
  determine best focus.
• For Sun test no additional analysis required.
• For lamp test analyze focus as a function of
  offset and position to separate stim tel and HMI
  curvature.
• Codes are mostly ready.
• Procedure
• STOL status Exists for Sun test. Does not exist
  for lamp test.
• Shop order status Does not exist

13
Image Quality MTF

• Purpose
• Determine the MTF variation as a function of
  image position.
• Requirements
• Astigmatism should be a fraction of a focus step.
  The MTF at any k should not be degraded by more
  than that corresponding to a(?) focus step. 10
  or better knowledge is desirable.
• Description
• Determine spatial power as a function of k and
  image position at best focus.
• Test configuration
• Stimulus telescope with lamp and desired
  target(s) (dots). Sun may also be used to
  illuminate target.
• Also do with sunlight.
• Test plan
• Same as for distortion. Also use sun focus
  series.
• Data analysis
• At each leg position and image position fit mode
  power as a function of k at best focus.
• For Sun test no additional analysis required.
• For lamp test analyze power as a function of
  offset and position to separate stim tel and HMI
  MTF.
• Codes are mostly ready.
• Procedure
• STOL status Exists.
• Shop order status Does not exist

14
Image Quality Image scale

• Purpose
• Determine the absolute image scale.
• Requirements
• The image scale should be between 0.494/pixel
  and 0.505/pixel.
• Description
• Take images of Sun. Determine diameter and
  compare to ephemeris.
• Test configuration
• Sun from heliostat.
• Test plan
• Take solar images at each focus position.
• Data analysis
• Determine solar image diameter. Look up diameter
  in in ephemeris. Divide numbers.
• Code exists.
• Procedure
• STOL status Exists.
• Shop order status Does not exist
• The test timeline Data already taken for other
  tests.
• No particular personnel required.

15
Contamination

• Purpose
• Determine if any large particles are present in
  the optical path.
• Requirements
• Any contaminants should not be large enough to
  degrade science.
• Description
• Using a pinhole camera mode look for shadows
  from contaminants and determine their position in
  the optical path by determining motion when
  moving pinhole.
• Test configuration
• Stimulus telescope with lamp or Sun and direct
  sunlight. PCU with hole plate.
• Laser in stimulus telescope with leg offsets.
• Test plan
• For each hole position or each leg offset take
  image in obs and cal mode.
• Also rotate each HCM at one or more hole and leg
  positions.
• Data analysis
• Offset images proportional to pinhole offset.
  Look for shadows coming into focus. Determine
  position in optical path from raytrace and
  proportionality constant used for shifting.
• For HCM rotations look for moving shadows.
• Codes exists for MDI.
• Procedure
• STOL status Does not exist
• Shop order status Does not exist

16
Polarization calibration

• Purpose
• Determine intsrument polarization matrix.
• Requirements
• See IPD.
• Description
• Using light with well determined polarization
  determine instrument response.
• Test configuration
• Stimulus telescope with lamp or Sun and sunlight
  from heliostat.
• Test plan
• Using PCU take series of images with various PCU
  and instrument settings.
• Data analysis
• Too complicated to describe here.
• Codes are ready.
• Procedure
• STOL status Does not exist
• Shop order status Does not exist
• The test timeline 50-100 images in obs and
  calmode required for Sun and lamp. Total one day.
• No particular personnel required.