ACHROMATIC PHASE SHIFTER BY REVERSAL OF ELECTRICAL FIELD VECTOR AT REFLECTIONS

摘要

DARWIN is an ESA space mission for the detection of extrasolar planets by nulling interferometry. Beams emerging from several telescopes are interferometrically combined. It is of crucial importance for the success of the mission to ensure that the combination of the light beams occurs with the correct phase difference. The required phase shift has to be introduced for the full spectral range of the instrument and with high accuracy. Phase shift deviations weaken the nulling performance and lead to the observational vanishing of otherwise detectable planets. Consequently, the achromatic phase shifter is an important element. Therefore, ESA has started a technology study to investigate both theoretically and experimentally several phase shifting concepts. This paper describes one out of several promising candidates. It works with the reversal of electrical field at reflections and is, therefore, intrinsically achromatic. In addition to the functional description of the element, the required performance and results of the performance and sensitivity analysis are given.