A method is provided of producing an optical filter. The method comprises depositing a first mirror layer onto a substrate; depositing an insulating layer on the first mirror; exposing at least some of a plurality of portions of a surface of the insulating layer to a dose of energy; developing the insulating layer in order to remove a volume from the at least some of the plurality of portions of the insulating layer, wherein the volume of the insulating layer removed from each portion is related to the dose of energy exposed to each portion, and wherein a remaining thickness after the removal of the volume from each portion of the insulating layer is related to the dose of energy exposed to each portion. The method further comprises depositing a second mirror layer on the remaining thickness of each of the plurality of portions of the insulating layer.