Co-Authors:
Lindner, M., OFIL Ltd., Kiryat Weizmann Science Park, Bldg. 13A, Rehovot 76100, Israel
Elstein, S., OFIL Ltd., Kiryat Weizmann Science Park, Bldg. 13A, Rehovot 76100, Israel
Wallace, J., OFIL Ltd., Kiryat Weizmann Science Park, Bldg. 13A, Rehovot 76100, Israel
Lindner, P., OFIL Ltd., Kiryat Weizmann Science Park, Bldg. 13A, Rehovot 76100, Israel
Abstract:
A solar blind UV bandpass filter technology has been developed which is appropriate for use with all types of UV imaging devices under full daylight conditions. This technology is based on dye doped polymer films that provide the critical solar UV blocking and the required sharp rejection slope, due to their intense absorption bands in specific portions of the UV. These films are combined with other components that block visible and near IR light to form selective and very efficient sun blocking UV bandpass filters. This technology is very flexible and permits tailoring of the filter transmission and its blocking characteristics. Solar blind bandpass filters based on this technology have been produced for use with MCP imagers with CsTe and RbTe photocathodes. Filter characteristics include 10% - 25% peak transmission, bandwidths (FWHM) of 16 - 22 nm and out of band blocking levels in excess of 12 OD. Using these filters, under direct midday summer sun, background signal levels less than 10 photons per second were obtained, when integrated over the entire field of view of the imager. Under development is a filter for use with back illuminated CCDs (BCCDs). Target specifications include 15% peak transmission, 20 nm bandwidth and substantial blocking of solar radiation from 290 to 1100 nm. Feasibility for CCD imaging in the solar blind range was proven with a BCCD camera.