The document discusses the calibration and observation modes of the IMaX instrument. It describes the process for calibrating exposure time, focus, wavelengths, file names, phase diversity, dark current, and flat field. It also summarizes the standard and new observing modes, including parameters, demodulation matrices, and how the new modes were implemented to work around timing restrictions.

1. IMaX: Calibrations and
Observations
The software's point of view

2. Calibrations and Observations
Exposure Time Standard Observing
● ●
Modes (OM)
Focus
●
VS, VM
–
Wavelenghts
●
LS, LM
–
Phase diversity
●
DM
–
Flat field
●
New OM
●
Dark current
●
V3, V5, V6, V7,
–
V12
L3, L5, L6, L7,
–
L12

3. Calibrating: Exposure Time
It acquires six images with increasing
●
exposure time.
It calculates the average for every image
●
(centered square 500x500) and ignores the
ones with an average over 85% of the max
value for a pixel.
It adjusts a line with the rest of the points and
●
takes the value corresponding to 2500
counts.

4. Calibrating: Exposure Time
Use of “CalibrateExposureTime” DECO.
●
This DECO takes six different times (in
●
milliseconds) as parameters.
It sets the Etalon voltage to the 5th of the VS OM.
●
It needs the dark current image.
●
It calibrates both cameras.
●
It updates CF (HD & Mem).
●
ImageAcquisition.Camera_1_ExposureTime &
ImageAcquisition.Camera_2_ExposureTime

5. Calibrating: Focus
It takes a single image and calculates RMS
●
for a centered square (500x500).
RMS:
●
standard deviation
RMS=
average

6. Calibrating: Focus
Use of TC “CalculateContrast”. Long duration
●
& low priority.
Process coordinated by the ICU.
●
It just uses camera 1.
●
It needs dark current and flat field image.
●
It sets the Etalon voltage to the 5th of the VS
●
OM.
It sends a HK with the calculated contrast.
●

7. Calibrating: Wavelengths
It takes images with increasing wavelength
●
values.
It calculates an average for every image in a
●
centered square(50x50). It takes the
minimum average and two from every side. It
adjusts a parabola for these five points. The
minimum of the parabola allows us to obtain
the offset of the line ('a').
λ=a+bV
This way we can obtain the new voltages for
●
the Observing Modes.

8. Calibrating: Wavelengths
Use of CalibrateWavelengths DECO.
●
It takes v0, v1 and vdelta as parameters.
●
It needs flat field and dark current images.
●
It just uses camera 1.
●
It calculates the new 'a' coefficient and writes
●
it to the CF (HD & Mem).
It recalculates the new CF voltages to all the
●
OM with the new 'a' coefficient and writes it
to the CF (HD & Mem).

9. Calibrating: File names
The images used for calibration are stored in
●
the ICU DSS.
cal_exp_cam_x_n_y.raw, where x is the
●
camera and y is the exposure time argument
number.
cal_focus_cam_1_n_x.raw, where x is an
●
increasing counter of the focus calibration
carried out.
cal_lambda_v_x.raw, where x is the voltage
●
in counts.

10. Calibrating: Phase Diversity
It sets the Etalon voltage to the 5th of the VS OM.
●
It sets ROCLIs to p1 of the VS OM.
●
Accumulation?
●
Truncation bits: 0
●
No demodulation
●
It sets the PD at the beginning and unset at the
●
end.

11. Calibrating: Dark current & flat
field
Provided by the scientist team as raw images
●
during AIV in Esrange.

12. Former Observing Modes
The former observing modes takes the the
●
following parameters from the CF.
Grouped by OM (VS, VM, LS, LM & DM):
●
Iddle time
–
Discarded frames
–
Accumulations
–
Truncation bits
–
Demodulate
–
Etalon voltages
–
ROCLI voltages
–

13. Former Observing Modes
Grouped by tuning mode (FPTM, ITM, DMM)
●
and Camera
Demodulation matrix
–
All of them have only one:
●
Camera 1 exposure time
–
Camera 2 exposure time
–
Max observing time
–
Max number of cycles
–
Max time to enter science mode
–
Lambda to voltage function coefficients
–

14. New Observing Modes
All of them use the Configurable mode for (including
●
V3, V5, L3 and L5):
Iddle time
–
Discarded frames
–
Accumulations
–
Truncation bits
–
Demodulate
–
Etalon voltages
–
ROCLI voltages
–

15. New Observing Modes
V3, V5, V6, V7and V12 use FPTM
●
demodulation matrix
L3, L5, L6, L7 and L12 use ITM
●
demodulation matrix
All of them have only one (same as former):
●
Camera 1 and camera 2 exposure time
–
Max observing time
–
Max number of cycles
–
Max time to enter science mode
–
Lambda to voltage function coefficients
–

16. New Observing Modes
Due to timing restrictions, all of them use
●
FPTM tuning mode.
Wavelengths are fixed and translated to
●
voltages at the beginning of the execution
with the 'a' and 'b' coefficients from the CF.
For the V# OM, the ROCLI
●
retardances(number of retardances and
values) and truncation bits are copied from
the Vector Spectropolarimeter OM values.
The demodulation matrix applied are the
ones for the FPTM.

18. New Observing Modes
For the L# OM, the ROCLI
●
retardances(number of retardances and
values) and truncation bits are copied from
the Longitudinal Spectropolarimeter OM
values. The demodulation matrix applied are
the ones for the ITM.

19. New Observing Modes:
Simulating ITM with FPTM
Because L3, L5, L6, L7 and L12 are carried
●
out with a FPTM, some tricks have to be
applied:
Because FPTM needs 4 polarizations for the
–
ROCLIs, the 2 polarizations are performed
twice.
The 4x4 demodulation matrix is built from the
–
2x2:

a b 0 0

ab c d 0 0
⇒
cd 0 0 a b
0 0 c d

20. Observing DECOs
SetObservingMode(dswMode, camera,
●
ccdTimeExposure, iddleTime, accumulations,
truncation, demodulation, wavelengthsNo,
RocliNo, wavelengths[5], retardancesR1[4],
retardancesR2[4], discards[5], cycles, time)
StartVectorSpectropolarimeterOM(cycles,
●
time), same for
StartVectorMagnetographOM,
StartLongitudinalSpectropolarimeterOM,
StartLongitudinalMagnetographOM and
StartDeepMagnetographOM.

21. Observing DECOs
StartConfigurableOM(cycles, time,
●
tuningMode)
StartV3ObservingMode(accumulations,
●
cycles, time, demodulation), same for
StartV5ObservingMode, StartV6ObservingMode,
StartV7ObservingMode, StartV12ObservingMode,
StartL3ObservingMode StartL5ObservingMode,
StartL6ObservingMode, StartL7ObservingMode
and StartL12ObservingMode.

22. Observing DECOs
ChangeCF_LambdaToVoltageCoefficient_A(a,
●
writeToCFHD)
ChangeCF_LambdaToVoltageCoefficient_B(a,
●
writeToCFHD)