Patent ID: 6476919
Filing Date: 2002-11-05
Classification: G01M

Abstract:
A polarization independent reflectometry of separating low-coherence light into two parts, entering one of the parts in a measured optical circuit as measurement light and giving the other a group delay that can be changed arbitrarily as local light signal, then combining the local light signal with reflected light signal provided by reflecting the measurement light at each point responsive to a propagation distance of the measured optical circuit and causing the reflected light signal and the local light signal to interfere with each other, detecting the intensity of the interference light, and measuring a reflection intensity at each point responsive to the propagation distance of the measured optical circuit as a function of the group delay from the intensity of the interference light, wherein low-coherence light having a polarization degree of 0.3 or less is used and with the polarization degree held, the reflected light signal and the local light signal are caused to interfere with each other, whereineither the local light signal or the reflected light signal is disposed in a linear polarization state, intensities I0 and I90 of interference light when the polarization state of either the local light signal or the reflected light signal is rotated &thgr;=0Â° and &thgr;=90Â° in a predetermined delay amount are measured, I0+I90 is found, and the reflection intensity at the point responsive to the propagation distance of the measured optical circuit corresponding to the predetermined group delay is measured.