1. Jesper Schou Instrument Scientist jschou@solar.stanford.edu
HMI00375
Calibration
Jesper Schou
Instrument Scientist

2. Calibration – Overview
Purpose and Philosophy
Calibration components
Test methods
Subsystem calibrations
Calibrations of integrated instrument
Ground based sunlight tests
On-orbit calibrations, characterization and trending
Future steps

3. Purpose and Philosophy
Enable calibration of data taken on orbit
Meet science requirements
Maximize science return
Determine optimal observing sequences
Actual performance determines optimal framelist
Quantify performance versus requirements derived in Instrument Performance Document (IPD)
Derive actual observables performance based on IPD derivations
Canned procedures
Rapid characterization
Repeatable
Coordinate with I&T

4. Calibration – Test Methods
Calibration sources
Tunable laser
Map filter profiles
Stimulus Telescope with test targets
Reverse optical system
Useful to measure optical distortions etc.
Polarization calibration GSE
Designed by High Altitude Observatory
Based on system currently being developed
The Sun
Provides excellent wavelength reference
Near realistic testing possible
Use existing LMSAL setup

5. Calibration – Subsystems
Some properties can only be measured before assembly
Detailed filter transmission profiles
Waveplate and polarizer properties
Angular dependencies
Etc.
Different levels of assemblies
Individual optical elements, e.g.
Waveplates
Beamsplitters
Polarizers
Filter sub elements
Lyot elements
Entire filters or other subsystems
Assembled Lyot filter
Each Michelson
Telescope

6. Calibration – Integrated Instrument
Sunlight and test sources
Essential for instrument characterization
Understand instrument before launch
Minimize commissioning time
Develop analysis algorithms
Baseline for trending
Sunlight tests of the integrated instrument are essential to optimize the use of the instrument on orbit.

7. Calibration – On Orbit Various time scales Trending
Daily
Calibration mode images
Weekly to monthly
Detunes for filter calibration
Polarization tests
Monthly to yearly
Spacecraft rolls and off-points for distortion and flat field measurements
Dark frames and light transfer curves
Special opportunities
Mercury transits and eclipses by the Moon to measure image scale
Trending
Filter drifts
Throughput degradation
Mechanism performance
Closely related to spacecraft and instrument operations

8. Future Steps Calibration plan available by CDR
Updated throughout mission
Sunlight tests preferably scheduled for times with reliable weather