A photoelastic-modulator-based motional Stark effect polarimeter for ITER that is insensitive to polarized broadband background reflections

Abstract

A motional Stark effect polarimeter insensitive to polarized broadband light is proposed. Partially polarized background light is anticipated to be a significant source of systematic error for the ITER polarimeter. The proposed polarimeter is based on the standard dual photoelastic modulator approach, but with the introduction of a birefringent delay plate, it generates a sinusoidal spectral filter instead of the usual narrowband filter. The period of the filter is chosen to match the spacing of the orthogonally polarized Stark effect components, thereby increasing the effective signal level, but resulting in the destructive interference of the broadband polarized light. The theoretical response of the system to an ITER like spectrum is calculated and the broadband polarization tolerance is verified experimentally.

Deformaciones de haces cilíndricos y cónicos al atravesar una placa plano-paralela de cristal uniaxial

“…En varios trabajos anteriores se han abordado problemas relacionados con la formación de imágenes [2][3][4][5][6]7], con el camino óptico [8,9] y las figuras de interferencia [10,11] para distintos cortes del cristal. En los últimos años hemos obtenido expresiones analíticas generales [12,13] que han permitido el desarrollo de polarímetros solares [14] e interferómetros para diagnóstico de plasma [15,16]. Asimismo, los estudios de patrones de interferencia conoscópicos [17] nos han permitido desarrollar moduladores y demoduladores de fase birrefringentes [18,19,20].…”