There's this attachment called an "Anti-Reflection Device"[0] that goes in front of rifle scopes. It's basically a honeycomb sunshade that, like the name says, minimizes reflections from the lens to make the shooter harder to spot. The cool and unintuitive thing about this gadget is that the honeycomb pattern doesn't actually appear when viewed through the scope. It's the exact same principle at play here.

[0] http://www.amazon.com/Tennebrex-Killflash-Scope-Anti-Reflect...