[RASMB] Dark interference fringe pattern

[Rufer, Arne]

Dear colleagues,

we recently encounter problems with the interference optical system on our XLI (upgraded to Proteome Lab version) in that the fringe pattern looks very dark (please see attached screenshots). Beckman field service recommended to us to clean the lenses in the laser housing of the monochomator arm (which we did paying attention to reinstall the lens in the correct orientation) and to clean/exchange the filter above the condensor lens. While intermittantly the brightness/contrast of the fringe pattern improved, we are back to "very dark" after trying to further clean things up. What remains also is a concentric interference pattern superimposed to the expected fringes, which you can see on the left side of the fringe patttern in the second screen shot. This ghost pattern is also visible when we look at the scallop position or an empty cell hole.
Any suggestion as to how we can get our machine back to normal would be greatly apprecieated.

Best regards,

Arne







Dr. Arne Rufer
F. Hoffmann-La Roche AG
PROBMO Optical Spectroscopy
065/207
CH-4070 Basel
Tel: 0041-(0)61-6882126
arne.rufer at roche.com<mailto:arne.rufer at roche.com>

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