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NOTE: Most of the High Level Science Products are unavailable while unscheduled maintenance is being performed. They will be incrementally restored over the course of this week. We apologize for any inconvenience.

FUSE Gratings

Caption: A prototype FUSE spectrograph grating being removed from a vacuum tank in a clean room at Jobin Yvon in France. The FUSE gratings are approximately a foot square, and contain some 5300 - 5800 lines per millimeter etched onto its surface. (The exact number changes as a function of position across each grating, and they are slightly curved, so we can't strictly call them parallel!) These etchings are what disperse far-UV light into a spectrum for analysis, and provide the high spectral resolution of the spectrograph. Placing these complicated etchings onto the curved surface of the grating was a particularly difficult task carried out by our French colleagues.

It is interesting to note that if the lines on a FUSE grating were all placed end to end, the resulting line would be over 300 miles long!

(Click on photo to see larger version!) [519 Kb gif]

Caption: A side view of the top end of FUSE during integration at JHU/APL. This picture shows two of the four FUSE gratings (under red covers) as mounted in the spectrograph. (May. 1998.)

(Click on photo to see larger version!) [400 Kb gif]