OPTICAL ELEMENT HAVING A COATING OF HIGH DIFFUSIVITY

摘要

An optical element has a substrate body made from transparent plastic and a coating having multiple layers. The coating includes a hard lacquer layer adjoining the substrate. The coating has a diffusivity ensuring the absorption of water molecules passing through the coating in the substrate and the release of water molecules from the substrate through the coating from an air atmosphere on that side of the coating facing away from the substrate with a flow density which, proceeding from the equilibrium state of the quantity of water molecules absorbed in the substrate in an air atmosphere at 23° C. and 50% relative humidity, brings the setting of the equilibrium state of the quantity of water molecules absorbed in the substrate in an air atmosphere at 40° C. and 95% relative humidity within an interval not more than 10 h longer than for setting this equilibrium under corresponding conditions with an identical uncoated substrate.

主权项

1. An optical element comprising:
a substrate body made of a plastic transparent in the visual spectral region; a coating having a plurality of layers including a hard lacquer layer adjoining said substrate body and further having a first side facing away from said substrate body; said coating having a diffusivity (DF) configured to ensure an absorption of water molecules passing through said coating into said substrate body and a release of water molecules from said substrate body through said coating from an air atmosphere arranged on said first side of said coating; said air atmosphere having a moisture flow density (jD); said diffusivity (DF) being further configured to, starting from a first equilibrium state of the amount of water molecules absorbed in said substrate body at an air atmosphere at 23° C. and 50% relative humidity, effect a setting of a second equilibrium state of the amount of water molecules absorbed in said substrate body at an air atmosphere at 40° C. and 95% relative humidity within a first time interval; and, said first time interval being at most ten hours longer than a second time interval required for a setting of said second equilibrium state starting from said first equilibrium state in an uncoated substrate body identical to said substrate body.