868 F.2d 1251 (Fed. Cir. 1989) Cited 391 times
Holding that the phrase "[a]n optical waveguide" in the preamble of the claim language was meant to limit claim scope to "optical waveguides" rather than all optical fibers because the "specification [made it] clear that the inventors were working on the particular problem of an . . . optical communication system not on general improvements in conventional optical fibers"