Large Axial Range Frequency-Domain Optical Low Coherence Interferometry

Abstract

In this letter, we propose a new experimental setup to extend the measurement range of frequencydomain low coherence interferometry (FD-LCI) from 3 mm to 2 cm. The FD-LCI can be extended to the technique of frequency domain optical coherence tomography by performing additional lateral scanning. This new and simple arrangement just attaches an extra interferometer before the spectrometer in a typical FD-LCI setup. With this configuration, it is possible to overcome the limitation of the dynamic range of the conventional technique. This allows us to measure the optical path difference of the sample of interest, which is outside the detection range of the spectrometer, using an extra interferometer as a tuner system. In addition, this tuning allows significant minimization of the effects produced by the fall-off. The accuracy of the new system is obtained by adding the FD-LCI and the tuning micrometric translator accuracies. In our experimental setup, this value is 20 μm.

OCT in Applications That Involve the Measurement of Large Dimensions

“…In this context, this chapter reports and discusses a simple and self-calibrated fiber-optic interferometric system based on the swept source optical coherence tomography (SS-OCT) technique, especially suitable when the measurement of large dimensions (several centimeters) is necessary as those ones involved in industrial metrological applications [32][33][34][35][36][37]. Its constituent parts are analyzed, and several applications are shown, including the measurement of several centimeter distances, characterization of multilayer structures, simultaneous determination of thickness of the wall, internal and external diameter of glass containers, thickness measurements in opaque samples (which allows the use of the system to perform profilometry of mechanical parts) or where the refractive index is unknown, etc.…”