Minimum antireflective coating thickness for blue light on glass

[Jodi]

HI; Could someone please help me with this question: Calculate the minimum thickness needed for an antireflective coating (n=1.35) applied to a glass lens in order to eliminate blue (458 nm) reflections for light at normal incidence? How would I go about this question? Thanks.

 

[Berislav]

Use destructive interference.

 

[Pengwuino]

You should have a very very simple formula to figure this out.