Elliptical polarization effects in a chromatically addressed Faraday current sensor

• Published in: Measurement science & technology 1999-01, Vol.10 (1), p.25-30
• Main Authors: Li, G D, Aspey, R A, Kong, M G, Gibson, J R, Jones, G R
• Format: Article
• Language: English
• Subjects: Atomic and molecular physics; Exact sciences and technology; Filters, zone plates, and polarizers; Fundamental areas of phenomenology (including applications); General equipment and techniques; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Molecular properties and interactions with photons; Optical activity and dichroism; magnetooptical and electrooptical spectra; Optical activity, optical rotation; circular dichroism; Optical elements, devices, and systems; Optics; Physics; Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing
• ISSN: 0957-0233; 1361-6501
• DOI: 10.1088/0957-0233/10/1/008

Optical polarization processes in a parallel-sided glass element used in a chromatic modulation Faraday rotation current sensor are considered. In these sensors, the path length necessary to produce sufficient rotation of the plane of polarization is produced by a multiplicity of reflections within the glass element. Such reflections induce ellipticity of polarization and this affects the performance of the sensor. Two reflection cases, corresponding to total internal reflections at a glass - air interface and reflections by aluminium-coated surfaces, are considered. It is shown that the resolution of the Faraday sensing is improved by minimizing the ellipticity of the polarization with the aluminium-coated reflections. However, a greater dynamic range and signal strength may be achievable with the total internal reflection element. (Original abstract - amended)