Spectral-domain low-coherence interferometry for phase-sensitive measurement of Faraday rotation at multiple depths.
We describe a method for differential phase measurement of Faraday rotation from multiple depth locations simultaneously. A polarization-maintaining fiber-based spectral-domain interferometer that utilizes a low-coherent light source and a single camera is developed. Light decorrelated by the orthogonal channels of the fiber is launched on a sample as two oppositely polarized circular states. These states reflect from sample surfaces and interfere with the corresponding states of the reference arm. A custom spectrometer, which is designed to simplify camera alignment, separates the orthogonal channels and records the interference-related oscillations on both spectra. Inverse Fourier transform of the spectral oscillations in k-space yields complex depth profiles, whose amplitudes and phase difference are related to reflectivity and Faraday rotation within the sample, respectively. Information along a full depth profile is produced at the camera speed without performing an axial scan for a multisurface sample. System sensitivity for the Faraday rotation measurement is 0.86 min of arc. Verdet constants of clear liquids and turbid media are measured at 687 nm.
Yi-Jou
YJ
Yeh
Adam J
AJ
Black
Taner
T
Akkin
D004867:Equipment Design; D019544:Equipment Failure Analysis; D007368:Interferometry / Q000295:instrumentation*; D008027:Light; D009391:Nephelometry and Turbidimetry / Q000295:instrumentation*; D044367:Phase Transition; D012031:Refractometry / Q000295:instrumentation*; D012399:Rotation; D012542:Scattering, Radiation; D013057:Spectrum Analysis / Q000295:instrumentation*