An optical device that includes a movable mirror part, comprising: a glass wafer with a first planar surface in at least one side of the glass wafer; a mirror wafer that comprises a package of a first layer of electrically conductive material, a second layer of electrically conductive material, and a third layer of electrically insulating material between the first layer and the second layer, wherein the first layer has a first side that faces away from the third layer, and the second layer has a second side against the third layer; a suspension spring structure for suspending the movable mirror part, wherein the movable mirror part and the suspension spring structure are fabricated of the second layer of the mirror wafer; a second cavity that extends from the first side of the first layer through at least the first layer of the mirror wafer, wherein the second cavity is circumscribed in the first side by a second planar surface; a reflecting layer on a surface of the second side of the second layer and carried by the movable mirror part in the bottom of the second cavity; a cap wafer that has a third side and a fourth side, and includes a first cavity that extends from the fourth side of the cap wafer into the cap wafer; wherein the cap wafer is bonded to the mirror wafer such that the third side faces away from the mirror wafer, and the fourth side is against the second layer of the mirror wafer; the glass wafer is bonded to the mirror wafer such that the first planar surface of the glass wafer extends as a plane over the second cavity and is in bonded abutment with the second planar surface; a hermetically closed space that encloses the movable mirror part and the suspension spring structure extends between the first planar surface of the glass wafer and a bottom of the first cavity in the cap wafer; characterized by a piezoelectric actuation element formed on a surface of the enclosed suspension spring structure, on a side of the second layer that is opposite the second side, wherein the piezoelectric actuation element is configured to actuate the movable mirror part in response to electrical signals received through a conductive connection; and in that the conductive connection includes an electrical contact element accessible from the third side of the cap wafer, and a conductive via extending from the electrical contact element through the cap wafer; the conductive via is formed of a silicon material of the cap wafer, and is insulated with a surrounding glass filling that extends to form the fourth side of the cap wafer; and the piezoelectric actuation element is electrically connected to the conductive via by wiring fabricated on the same side of the second layer as the piezoelectric actuation element. a glass wafer with a first planar surface in at least one side of the glass wafer; a mirror wafer that comprises a package of a first layer of electrically conductive material, a second layer of electrically conductive material, and a third layer of electrically insulating material between the first layer and the second layer, wherein the first layer has a first side that faces away from the third layer, and the second layer has a second side against the third layer; a suspension spring structure for suspending the movable mirror part, wherein the movable mirror part and the suspension spring structure are fabricated of the second layer of the mirror wafer; a second cavity that extends from the first side of the first layer through at least the first layer of the mirror wafer, wherein the second cavity is circumscribed in the first side by a second planar surface; a reflecting layer on a surface of the second side of the second layer and carried by the movable mirror part in the bottom of the second cavity; a cap wafer that has a third side and a fourth side, and includes a first cavity that extends from the fourth side of the cap wafer into the cap wafer; wherein the cap wafer is bonded to the mirror wafer such that the third side faces away from the mirror wafer, and the fourth side is against the second layer of the mirror wafer; the glass wafer is bonded to the mirror wafer such that the first planar surface of the glass wafer extends as a plane over the second cavity and is in bonded abutment with the second planar surface; a hermetically closed space that encloses the movable mirror part and the suspension spring structure extends between the first planar surface of the glass wafer and a bottom of the first cavity in the cap wafer; characterized by a piezoelectric actuation element formed on a surface of the enclosed suspension spring structure, on a side of the second layer that is opposite the second side, wherein the piezoelectric actuation element is configured to actuate the movable mirror part in response to electrical signals received through a conductive connection; and in that the conductive connection includes an electrical contact element accessible from the third side of the cap wafer, and a conductive via extending from the electrical contact element through the cap wafer; the conductive via is formed of a silicon material of the cap wafer, and is insulated with a surrounding glass filling that extends to form the fourth side of the cap wafer; and the piezoelectric actuation element is electrically connected to the conductive via by wiring fabricated on the same side of the second layer as the piezoelectric actuation element.