Wide-field Solc-type birefringent filter

摘要

A 24-element wide-field Solc birefringent filter (WFSBF) has been produced and tested for the first time. WFSBF is asecond unit to the 3-unit BF designed for imaging solar magnetic fields in the FeI 6173 ? spectral line. WFSBFpassband full width at half maximum is 0.2 ?. The optical stage of the Solc BF is apodized. The main passband has atwo-peak profile, to increase BF transmittance in spectral line wings. The neighbouring passbands at 2 ? are cut off bythe first BF unit. To measure magnetic fields, a narrower passband of the third BF unit is to scan the spectral line wingsin the ±0.05? positions, in accordance with two-peak positions of the Solc filter profile. The wide field of view (FOV) ofthe Solc filter was reached with composite birefringent stages of 24 positive artificial paratellurite and 24 negativenatural calcite crystals. FOV of a composite stage is eleven times larger than that of the only-calcite one. The calculatedpassband is compared to the experimental one. Technological aspects of the manufacture as well as devices for plateorientation are discussed.© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.