Wide-field Solc type birefringent filter

Solc type birefringent filter (BF) has finished and tested. The BF is the second block of 3-blocks BF to image the solar magnetic fields. The main items of quality specifications on BF are high transparency, contrast and wide field of view. The apodized Solc BF is good enough for two items. Calculations show that a multicomponent Solc BF can give optimal two- peaks passband to measure magnetic fields. But such filter was not produced and because of it's very small field of view and strong tolerances for optical thickness and orientation of crystal elements. We manufactured the 24-elements wide-field Solc BF. The full width at half maximum is 0.2 Å, neighbor maxima at distance 2 Å are cut off by the first block BF. The passband of third block will be scan ±0.05 Å in accordance to two peaks without a transmittance lessening.The severe counted and technological tolerances were kept owing to the special way of treatment ant checking of the crystal elements. Wide field was got with using composed birefringent stages of positive (artificial paratellurite) and negative ( natural calcite) crystals instead of simple elements. Field of view of composed stage is thirteen times more than one of simple stage. The calculated two peaks passband and experimental one are compared. Technological aspects are discussed.