Micro- or nanostructured optical element

A micro- or nanostructured optical element (1) is proposed comprising: a membrane (3) with an array of holes (5), the membrane (3) comprising a membrane light wave facing surface; an array of pillars (7) sized and shaped such that a respective pillar (7) is configured to be at least partially received in a respective hole (5), the respective pillar (7) defining a central pillar axis, and comprising a pillar light wave facing surface; a support (9) configured to support the pillars (7); and an actuation mechanism configured to selectively generate a relative displacement between the membrane (3) and the pillars (7) along the central pillar axes to thereby define a first optical element reflectance state, where the membrane (3) is in an elevated position with respect to the support (9), and a second, different optical element reflectance state, where the membrane (3) is in a lowered position with respect to the support (9) such that the respective pillar (7) extends through the respective hole (5). In the first optical element reflectance state, the membrane light wave facing surface is substantially flush with the pillar light wave facing surfaces, or the membrane light wave facing surface is placed beyond the pillar light wave facing surfaces.