A novel intensity modulated fiber optic displacement sensor based on the relative motion of an optical fiber and a graded index lens is described. The technique allows the use of either single- or multimode optical fibers in either single or dual fiber configurations. Displacement sensitivities of 25 Å have been measured using 50-µm core diam multimode fibers, with a light emitting diode source. Theoretical sensitivities of the order of 0.01 nm are predicted with the use of single-mode fibers.
© 1990 Optical Society of America
Patrick J. Murphy and Thomas P. Coursolle, "Fiber optic displacement sensor employing a graded index lens," Appl. Opt. 29, 544-547 (1990)