Abstract: The invention relates to a method for manufacturing a light weight optical mirror or a monolithic mirror comprising at least one cooling channel, the method comprising forming a mirror body by iteratively depositing a metallic powder in layers and applying, for each of the layers, heat at least in a subarea of this layer, thereby fusing or sintering the powder in this subarea and bonding it to a previously deposited layer, the powder remaining in an unfused state in at least one region, the method further comprising forming at least one cavity within the carrier by removing the unfused powder from said region and producing a mirror surface at a closed surface of the mirror body. The invention further relates to an optical mirror and to an optical device.