UV devices for solar blind and background limited detection

A technology has been developed for producing polymer based UV absorption filters. The filters are fabricated by embedding UV absorbing dyes in polymer matrices. A selection of dyes with different chromophores have been synthesized. Each provides a high level of blocking within a specific band in the UV. Polymer filters are combined with other filtering components that absorb in the visible and IR regions to form selective UV bandpass filters. Typical filter combinations achieve transmission levels of 10% and more in the mid UV and absorption levels reaching up to 12 OD and higher in the remaining UV, visible and near IR regions. An important advantage of these UV bandpass filters is the exclusive use of absorption type components. This provides consistent performance over wide acceptance angles. Filters with spectral transmission profiles optimized for specific detection applications in the UVc and UVb regions have been designed. Optimization takes into consideration the spectral response of the detector to achieve the sensor spectral response required by the application. Solar blind PMT sensors incorporating these files have demonstrated blindness to noontime solar illumination while maintaining good response from 245 to 270 nm in the solar blind range. Complete blocking of solar radiation and good sensitivity in the solar blind range has also been achieved with SiC solid state photodiodes.