M74050
1/4M IMAGING SPECTROGRAPHS
30
8.2 F NUMBER MATCHING
The MS260i spectrograph is an F/3.9 instrument. Without matching the F/# of the incoming light
beam, stray light increases and throughput of desired signal suffers. To illustrate this concept, the
photos below show a fiber optic cable placed at the entrance of a spectrograph. Fibers are typically
F/2. The Oriel model 77529 may be used to match the F/# to the spectrograph.
Figure 21: Mismatched F Numbers Resulting in Stray Light
Figure 22: F Number Matcher Used with Fiber Optic Cable