Checking the parallelism of the FP

- First, in the GriF Xterm, type "more .,grifh.par" to check that the the BCV_X and BCV_Y values are the default ones

- from the first wavelength calibration scan (or any following scan of the 2.06163 µm line), build a phase map by typing the Phase Xterm "remsh noeau grifpar fichier.log", where fichier.log is the logfilename of the corresponding scan (eg 701324.log). This will create a phase.fits file in /h/grif.

- from any appropriate software (idl, saoimage, ...), check that on this phase map, the central pattern is centered on the detector as shown on the following images



On the obtained phase map, the range of values is hardly scattered (~1-1.5).

- if this is not the case:
    - check the CS100 setup values
    - modify by a small amount the BCV_X and/or BCV_Y values by making a new scan of the 2.06163 µm argon line. By looking at the direction of displacement of the fringes during the scan, one can determine how to change the BCV_X and/or BCV_Y values (see the following scheme)

Fig.: moving direction of the fringes when the FP is not parallel