LESIA - Observatoire de Paris

Checking the parallelism of the FP

mercredi 12 novembre 2008

- First, in the GriF Xterm, type "more .,grifh.par" to check that the the BCVX and BCVY 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 BCVX and/or BCVY 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 BCVX and/or BCVY values (see the following scheme)