Optical Coherence Tomography-based Structural Vibration Sensor System

An optical coherence tomography-based structural vibration sensor system is reported. The system employs a halogen tungsten lamp as the low-coherence light source and a broadband CCD-based spectrometer as the detector. Unlike traditional piezoelectric accelerometer, the sensor system is non-contact and it measures the surface displacement of a sample directly. Due to the extreme broadband of the thermal light, the sensor system can offer a high axial resolution of 0.9 μm. Experimental result demonstrated that both the vibration amplitude and frequency can be quantified by the current sensor system. The measurable frequency range currently achieved is 0-250 Hz, and this could be easily increased to a few KHz if the latest CCD-based spectrometer is employed. We believe that the developed sensor system is an ideal tool for in-situ monitoring of these low-frequency micro-vibrations in high-precision manufacturing and measuring system.