Optical Filters For High Resolution Ultraviolet Imaging Systems

Ultraviolet filters of improved resolution quality have been developed for the Air Force Geophysics Laboratory (AFGL), to enable the acquisition of high-resolution images of missile plumes and similar phenomena. The objectives were to provide a specified passband in the region 2000-4000A, and reject all visible radiation to better than six orders of magnitude, without degrading the transmitted image resolution by more than 5 line-pairs per mm. The resulting filter set has peak transmittance better than 25 percent, with rejection in the visible better than eight orders of magnitude. Inherent image definition capability is estimated better than 40 line-pairs per mm. The imaging performance of the intended camera system (estimated 15 to 20 line-pairs per mm) should not be perceptibly degraded. Based on these results, a more general design and production capability for high-resolution UV filters is considered feasible.