Chains of these devices are used as multiplexers and demultiplexers in WDM systems. In one type of these devices, the quantity “pi times the square root of R all over one minus R” defines the finesse. Gyroscopes such as RLGs (10[1]-5[1])and FOGs are examples (10[1])of these devices that operate (10[1])using the Sagnac (“sahn-YAHK”) effect. (10[1]-5[1])A (10[1])type (10[1])of (10[1])these (10[1])devices called an etalon consisting (10[1])of a cavity (10[1])that filters out waves not in resonance is named (10[1])for (-5[1])Fabry and (10[1])Pérot. (10[9])One of these optical (10[1])devices (10[1])consisting (10[1])of a stone slab in a pool of (10[1])mercury (-5[2])failed to detect (10[2]-5[2])a (-5[1])0.04 (10[3])fringe (-5[1])shift (-5[1])induced (10[2])by the Earth’s (10[1])motion. (-5[2])For 10 points, name these devices (-5[1])that split (10[1])a beam of light and later (-5[1])recombine (-5[1])them to form (-5[1])patterns, (0[1])which (10[1])include (10[1])one used to disprove the luminiferous (10[1])aether (10[2])in the Michelson–Morley experiment. (0[1])■END■ (10[4]0[15])