Optical EngineeringSolid state optic vibration/displacement sensors
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Sensitivities, displacement range, and accuracy of two types of optical vibration sensors, one fiber optic with a light-emitting diode source (LED/FO) and the other with a laser diode source and small (~1 mm) optics (LD/SO) were designed, assembled, tested, and compared. For the configurations adopted, sensitivity of the LED/FO with a 400- ?m aperture was found to be about 1.13 mV/?m over a 0.2- to 1.0-mm range and 20.37 mV/? over a 1.5- to 2.5-mm range. LD/SO sensitivities were 22.28 mV/?m over a 2.0- to 3.0-mm range for the f /2 design and about 21 mV/?m over a 0.1- to 10-mm range for the f /5 design. Although the LD/small-optics arrangement is capable of yielding greater sensitivities over longer ranges, the lower cost yet still precise and accurate LED/FO configuration is more rugged and therefore better suited to the field and related in situ and embedded applications.