Solar blind and bispectral imaging with ICCD, BCCD, and EBCCD cameras

Absorption type solar blind ultraviolet (SBUV) filters with transmittance levels of 10 - 20%, FWHM band widths of 16 - 20 nm and blocking levels exceeding 12 OD have been developed for use with image intensified CCD (ICCD) cameras with CsTe, RbTe and CsRbTe photocathodes. Solar blind UV ICCD cameras equipped with these filters produce no measurable signals when directly viewing the sun at noon time in a summer day. Images of fire, gunfire flashes and high voltage transmission line corona were obtained in full daylight at high signal to noise ratio, by using these imagers. A solar blind filter was constructed for BCCD camera with UVAR coating. Images of fire and low power light sources can be obtained in full daylight when an appropriate solar blind filter is coupled to a BCCD camera. Results with bispectral imagers, combining solar blind UV images and images of the visible scene, are reported. For visualization of very weak UV sources use of solar blind image intensifiers is of advantage. This advantage can in principle also be achieved by EBCCD technology.