PROTECTIVE BLIND FOR OPTICAL DEVICES Russian patent published in 2013 - IPC G03B11/04 

FIELD: physics.

SUBSTANCE: protective blind has a housing, diaphragms and an optically transparent layer, having a selective coefficient of transmission (absorption) of light, made from materials which are chemically resistant to vapour and aqueous solutions of alkalis and acids, including hydrofluoric acid. The inner volume of the blind contains a gas or a mixture of gases at pressure which is not below ambient pressure. The optically transparent layer has at least one cylindrical cavity whose axis of symmetry coincides with the optical axis of the blind. The optically transparent end wall of the cylindrical cavity can be bent.

EFFECT: controlled variation of the angle of view and providing a stable light transmission coefficient when using the blind in a chemically aggressive medium.

2 dwg