An infra-red camera apparatus having a primary mirror assembly formed in a first molded plastic housing; and, a secondary mirror assembly formed in a second molded plastic housing and disposed in front of and in optical alignment with the primary mirror assembly for collecting an image. The first and second housings snap together for assembly of the camera. A focal plane array is disposed in optical alignment with the primary and secondary mirrors for receiving an image focused thereon by the secondary mirror. A substrate is added for supporting the focal plane array and system electronics, which are responsive to images formed on the focal plane array.