An optical device comprising: a housing enclosure having an inner surface and a housing flange, the housing flange having, at a proximal end, a circumferential flange extending outward from the inner surface; a lens cell holder including a body defining an outer surface and a lens cell holder flange extending outward from the outer surface, the lens cell holder flange being positioned between the housing flange and a retainer, the retainer being connected to the housing flange by mechanical threads defined on the outer surface of the housing flange; a lens assembly having one or more lenses that is mounted to the lens cell holder such that the lens assembly is configured to translate in an axial direction with respect to the housing enclosure and the lens cell holder; and a radial space defined between the outer surface of the lens cell holder and the inner surface of the housing enclosure that is sized to accommodate adjustment of the lens cell holder and the lens assembly in a radial direction with respect to the housing enclosure, wherein the lens cell holder and the lens assembly are movable in the radial direction within the radial space upon mating the lens cell holder flange to the housing flange of the housing enclosure and prior to fixing the retainer to the housing flange in order to adjust a line of sight of the optical device, and the line of sight of the optical device is established once the retainer is fixed to the housing flange, and comprising an O-ring mounted on the exterior surface of the housing flange proximal of the mechanical threads, the O-ring being enclosed by the exterior surface of the housing flange, the outwardly extending circumferential flange and the retainer. a housing enclosure having an inner surface and a housing flange, the housing flange having, at a proximal end, a circumferential flange extending outward from the inner surface; a lens cell holder including a body defining an outer surface and a lens cell holder flange extending outward from the outer surface, the lens cell holder flange being positioned between the housing flange and a retainer, the retainer being connected to the housing flange by mechanical threads defined on the outer surface of the housing flange; a lens assembly having one or more lenses that is mounted to the lens cell holder such that the lens assembly is configured to translate in an axial direction with respect to the housing enclosure and the lens cell holder; and a radial space defined between the outer surface of the lens cell holder and the inner surface of the housing enclosure that is sized to accommodate adjustment of the lens cell holder and the lens assembly in a radial direction with respect to the housing enclosure, wherein the lens cell holder and the lens assembly are movable in the radial direction within the radial space upon mating the lens cell holder flange to the housing flange of the housing enclosure and prior to fixing the retainer to the housing flange in order to adjust a line of sight of the optical device, and the line of sight of the optical device is established once the retainer is fixed to the housing flange, and comprising an O-ring mounted on the exterior surface of the housing flange proximal of the mechanical threads, the O-ring being enclosed by the exterior surface of the housing flange, the outwardly extending circumferential flange and the retainer.