Apr 17-22, Tunable filter wavelength scan and calibration of intensity ripple Y. Katsukawa (NAOJ) and SOT team

Apr 17-22, TF wavelength scan Wavelength scan by the tunable filter was performed to verify spectroscopic performance and its uniformity over the field-of- view. Two data sets –Solar spectra to check spectrum line profiles and their uniformity –Lamp source (emitting continuum light) to check intensity variation through the scan Each full FOV image is divided into 8x4 sub-images, and spectrum is created in each sub-image.

Apr 17-22, Wavelength scan of the solar spectrum lines (1) Mg I 5172A Fe I 5250A Black: Measured spectra Red: Atlas +TF ideal profiles

Apr 17-22, Wavelength scan of the solar spectrum lines (2) Fe I 5576A Na I 5896A Black: Measured spectra Red: Atlas +TF ideal profiles

Apr 17-22, Wavelength scan of the solar spectrum lines (3) Fe I 6302A H I 6563A Black: Measured spectra Red: Atlas +TF ideal profiles

Apr 17-22, Solar spectra by NFI These data sets show the line profiles are roughly consistent with the atlas spectra, and roughly uniform over the FOV. Two features can be seen in the spectra 1. Periodic intensity variation, especially significant in 5250A. 2. The line profiles are slightly shallower than the atlas spectra. In order to distinguish the solar spectrum features and intensity variation caused by the instrument, wavelength scans were carried out using a lamp source emitting continuum light.

Apr 17-22, Wavelength scan of a lamp source (1) Mg I 5172A Fe I 5250A Black: Measured intensity Red: Fitting result

Apr 17-22, Wavelength scan of a lamp source (2) Fe I 5576A Na I 5896A Black: Measured intensity Red: Fitting result

Apr 17-22, Wavelength scan of a lamp source (3) Fe I 6302A H I 6563A Black: Measured intensity Red: Fitting result

Apr 17-22, Intensity ripple in TF wavelength scan Amplitudes of the ripple are around 10 – 20 %, and are position dependent over FOV. They are also dependent on wavelengths. Periodic variation is dominant in 5172A and 5250A. We found two periods are dominant in the ripples. For the longer wavelengths, the ripple profiles are more complex. Many periods may be superposed.

Apr 17-22, Model of the intensity ripple TF consists of 8 calcite blocks and 8 tuning elements (motors). Each calcite block has a halfwave plate in the middle of the block to make wide fields. The tuning elements move periodically through the scan, and their periods are different from each other. The intensity ripple can be reproduced by giving errors to retardation of the halfwave plates in the calcite blocks 3 and 6. halfwave-6; del=0.1, halfwave-3; del=0.05, 5250A

Apr 17-22, Calibration of the intensity ripple If the intensity ripple is caused by the halfwave plates in the calcite blocks, the intensity modulation can be represented as a function of the motor positions (provided by encoders) of the tuning elements. Calcite blockMotor pos Calcite-02*(Motor-0)+(Motor-1) Calcite-1(Motor-1) Calcite-22*(Motor-2)+(Motor-3) Calcite-3(Motor-3) Calcite-42*(Motor-4)+(Motor-5) Calcite-5(Motor-5) Calcite-62*(Motor-6)+(Motor-7) Calcite-7(Motor-7) : Intensity amplitude for ith calcite block (Position dependent) : Phase of the motor position for ith calcite block (Position dependent) : Motor positions corresponding to ith calcite block a i and b i are derived by fitting of the intensity profiles at each position in FOV.

Apr 17-22, A amplitude and phase T  21  C Calcite-6 Calcite-3 Amplitude Phase

Apr 17-22, A amplitude and phase T  25  C Calcite-6 Calcite-3 Amplitude Phase The amplitude and phase are almost the same as those at T  21  C.

Apr 17-22, Spectra after calibration of I-ripple: 5250A Fe I 5250A Black: After corrected Red: Atlas +TF ideal profiles Black: Measured Red: Atlas +TF ideal profiles

Apr 17-22, A amplitude and phase distribution Calcite-6 Calcite-3 Amplitude Phase Amplitude Phase Amplitude Phase Calcite-5

Apr 17-22, Spectra after calibration of I-ripple: 6302A Fe I 6302A Black: After corrected Red: Atlas +TF ideal profiles Black: Measured Red: Atlas +TF ideal profiles

Apr 17-22, Spectra after calibration of I-ripple: 5576A Fe I 5576A Black: After corrected Red: Atlas +TF ideal profiles Black: Measured Red: Atlas +TF ideal profiles

Apr 17-22, Spectra after calibration of I-ripple: 5172A Mg I 5172A Black: After corrected Red: Atlas +TF ideal profiles Black: Measured Red: Atlas +TF ideal profiles

Apr 17-22, Spectra after calibration of I-ripple: 5896A Na I 5896A Black: After corrected Red: Atlas +TF ideal profiles Black: Measured Red: Atlas +TF ideal profiles

Apr 17-22, Spectra after calibration of I-ripple: 6563A H I 6563A Black: After corrected Red: Atlas +TF ideal profiles Black: Measured Red: Atlas +TF ideal profiles

Apr 17-22, Summary On orbit, the ripple patterns move with respect to the solar spectrum lines because the satellite Doppler motion and temperature changes in TF. But we can calibrate them because they are the patterns fixed to the motor positions. The spectrum line profiles are significantly improved by the calibration of the intensity ripple using the motor positions of the tuning elements. Similar wavelength scan data will be obtained at times in flight in order to verify tuning accuracy and the calibration function (amplitude and phase distribution) of the intensity ripple.

Apr 17-22, Broadband Filter Imager (1) CN bandhead Center: nm FWHM: 0.7nm Ca II H Center: nm FWHM: 0.3nm

Apr 17-22, Broadband Filter Imager (2) G-band Center: nm FWHM: 0.8nm Blue continuum Center: nm FWHM: 0.4nm

Apr 17-22, Broadband Filter Imager (3) Green continuum Center: nm FWHM: 0.4nm Red continuum Center: nm FWHM: 0.4nm