Optical element having a movable reflective cover comprising a 2-dimensional material

A process for the preparation of an optical element comprising the following process steps, which can be performed in any order:

• a. providing a support;
• b. attaching a cover to the support, wherein the cover comprises a 2-dimensional material;
• and
• c. providing a means for altering the position of the cover in relation to the support;
• wherein the cover has a value of transmittance divided by reflectance of not more than 0.5, the reflectance and transmittance being measured at a wavelength λ;
• and
• wherein λ is in the range from 10 nm to 20 μm;
• and wherein the 2-dimensional material has a thickness of 10 nm or less and comprises graphene or boron nitride or both.

An optical element comprising:

• a. a cover having a first surface and a second surface,
• b. a support, and
• c. a means for moving the second surface;
• wherein:
• wherein the cover is orientated with the first surface directed towards the support;
• wherein a part of the first surface is attached to the support;
• wherein a spatial arrangement of the second surface relative to the support defines a cover contour profile;
• wherein the means is adapted and arranged to move the second surface from a first cover contour profile to a further cover contour profile;
• and
• wherein the cover comprises a 2-dimensional portion which is one or more 2-dimensional materials, wherein the 2-dimensional portion has a thickness of 10 nm or less and comprises:
• (a) one or more selected from the group consisting of:
• C, BN, P, MoS2, MoSe2, MoTe2, WS2, WSe2, WTe2, GaS, GaSe, GaTe, NbS2, NbSe2, NbTe2, TaS2, TaSe2, TaTe2, TiSe2, VSe2, CrS2, CrSe2, B, Ge, Si, Si2BN, Sn, Pb, PtS2, PtSe2, PtTe2, Sb, Bi;
• (b) one or more transition metal chalcogenides, each being a transition metal chalcogenide not listed in (a);
• (c) one or more oxides, each being an oxide of a species listed in (a) or (b);
• (d) one or more atomic intercalated variants, each being an atomic intercalated vari-ant of a species listed in (a) or (b);
• or
• (e) one or more chemically functionalised derivatives, each being a chemically functionalised derivative of a species listed in (a) or (b);
• Wherein the cover has a value of transmittance divided by reflectance of not more than 0.5, for light incident the second surface, the reflectance and transmittance being measured at a wavelength λ;
• wherein λ is in the range from 10 nm to 20 μm, and
• wherein the cover comprises an amorphous portion, a metal portion, or an additive portion.