A process for manufacturing an optical microelectromechanical device, comprising: forming, in a first wafer of semiconductor material having a first surface and a second surface, a suspended mirror structure, a fixed structure, surrounding the suspended mirror structure, elastic supporting elements (84A-84D) extending between the fixed structure and the suspended mirror structure, and an actuation structure coupled to the suspended mirror structure; forming, in a second wafer of semiconductor material or glass, a chamber delimited by a bottom wall having a through opening; wherein forming a chamber comprises: selectively removing portions of a work wafer having a first surface and a second surface, wherein removing includes removing portions starting from the first surface of the work wafer to form a first recess and a second recess (13"), wherein the first recess extends within the work wafer from the second recess, wherein remaining portions of the first surface of the work wafer that surrounds the second recess form a contact surface; and thinning the work wafer from the second surface until reaching the first recess, thereby forming the through opening, the contact surface and an outer surface, opposite to the contact surface, of the second wafer; blackening the outer surface of the second wafer to cause the outer surface to be absorbant or diffusive with respect to light; bonding the contact surface of the second wafer to the first surface of the first wafer so that the chamber overlies the actuation structure and the through opening is aligned to the suspended mirror structure; bonding a third wafer to the second surface of the first wafer thus forming a device composite wafer; dicing the device composite wafer to form an optical microelectromechanical device. forming, in a first wafer of semiconductor material having a first surface and a second surface, a suspended mirror structure, a fixed structure, surrounding the suspended mirror structure, elastic supporting elements (84A-84D) extending between the fixed structure and the suspended mirror structure, and an actuation structure coupled to the suspended mirror structure; forming, in a second wafer of semiconductor material or glass, a chamber delimited by a bottom wall having a through opening; wherein forming a chamber comprises: selectively removing portions of a work wafer having a first surface and a second surface, wherein removing includes removing portions starting from the first surface of the work wafer to form a first recess and a second recess (13"), wherein the first recess extends within the work wafer from the second recess, wherein remaining portions of the first surface of the work wafer that surrounds the second recess form a contact surface; and thinning the work wafer from the second surface until reaching the first recess, thereby forming the through opening, the contact surface and an outer surface, opposite to the contact surface, of the second wafer; blackening the outer surface of the second wafer to cause the outer surface to be absorbant or diffusive with respect to light; bonding the contact surface of the second wafer to the first surface of the first wafer so that the chamber overlies the actuation structure and the through opening is aligned to the suspended mirror structure; bonding a third wafer to the second surface of the first wafer thus forming a device composite wafer; dicing the device composite wafer to form an optical microelectromechanical device. selectively removing portions of a work wafer having a first surface and a second surface, wherein removing includes removing portions starting from the first surface of the work wafer to form a first recess and a second recess (13"), wherein the first recess extends within the work wafer from the second recess, wherein remaining portions of the first surface of the work wafer that surrounds the second recess form a contact surface; and thinning the work wafer from the second surface until reaching the first recess, thereby forming the through opening, the contact surface and an outer surface, opposite to the contact surface, of the second wafer; blackening the outer surface of the second wafer to cause the outer surface to be absorbant or diffusive with respect to light; bonding the contact surface of the second wafer to the first surface of the first wafer so that the chamber overlies the actuation structure and the through opening is aligned to the suspended mirror structure; bonding a third wafer to the second surface of the first wafer thus forming a device composite wafer; dicing the device composite wafer to form an optical microelectromechanical device.