Tunable liquid-crystal filter for solar imaging at the He i 1083-nm line.
A Lyot-Ohman filter for imaging near the solar He i 1083-nm line is described. Fast and continuous spectral tunability is provided by nematic liquid crystals. This solid-state filter has a free spectral range of 2.35 nm and a spectral resolution of 0.135 nm at the operating wavelength of 1083 nm. A wide-fielded design was used for both static and electro-optic retarder elements, facilitating use in fast imaging systems. A first-light He i image of the Sun is presented.
Kopp
G A
GA
Derks
M J
MJ
Elmore
D F
DF
Hassler
D M
DM
Woods
J C
JC
Streete
J L
JL
Blankner
J G
JG