STRUMENTO OTTICO DI INGRANDIMENTO COMPRENDENTE UN DISPOSITIVO DI PROTEZIONE DELL'OCCHIO DELL'OSSERVATORE CONTRO IL LAMPO TERMICO NUCLEARE

The invention protects the eyes of users of telescopic weapon sights, eg tank gunners, against thermal radiation from the flash produced by battlefield nuclear weapons. A fast-acting reversible opto-electrical attenuating screen 2, eg of PLZT, is located across the field of view of the sight 1, a UV-activated fast-acting reversible photochromic filter 3 beyond the screen 2, an infra-red filter 4,5 beyond filter 3 and a mechanical shutter 6 beyond filter 4,5. Closure of shutter 6 and switching of screen 2 is initiated by the flash, but the shutter can only close relatively slowly. While it is closing, protection is given by the remaining elements which individually also protect succeeding elements from damage due to thermal overloading.