An optical post mount system, comprising: a post holder body including an upper end, a lower end, a post receiver adapted to receive an optical post therein, and a collar coupling surface disposed on the upper end of the post holder body, the collar coupling surface including a plurality of positioning elements disposed around a circumference of the collar coupling surface at predetermined angular positions; a mounting base disposed at the lower end of the post holder body in fixed relation thereto; and a post collar including an upper side, a lower side, a post aperture adapted to receive the optical post therein and extending from the upper side to the lower side, a post lock device adapted to secure the optical post relative to the post collar, and at least one collar positioning device disposed on the lower side of the post collar, the at least one collar positioning device being configured to engage the at least one positioning element of the post holder body and prevent relative rotational movement about a longitudinal axis of the post aperture between the post collar and the post holder body when the positioning element and positioning device are engaged, wherein either - each positioning element of the post holder body comprises a positioning relief formed in the collar coupling surface and each collar positioning device comprises a correspondingly formed protrusion element extending from a nominal surface of the lower side of the post collar in a direction that is parallel to the longitudinal axis, or - each collar positioning device comprises a positioning relief formed in the nominal surface of the lower side of the post collar and each positioning element of the post holder body comprises a correspondingly formed protrusion element extending from the collar coupling surface in a direction that is parallel to the longitudinal axis. a post holder body including an upper end, a lower end, a post receiver adapted to receive an optical post therein, and a collar coupling surface disposed on the upper end of the post holder body, the collar coupling surface including a plurality of positioning elements disposed around a circumference of the collar coupling surface at predetermined angular positions; a mounting base disposed at the lower end of the post holder body in fixed relation thereto; and a post collar including an upper side, a lower side, a post aperture adapted to receive the optical post therein and extending from the upper side to the lower side, a post lock device adapted to secure the optical post relative to the post collar, and at least one collar positioning device disposed on the lower side of the post collar, the at least one collar positioning device being configured to engage the at least one positioning element of the post holder body and prevent relative rotational movement about a longitudinal axis of the post aperture between the post collar and the post holder body when the positioning element and positioning device are engaged, wherein either - each positioning element of the post holder body comprises a positioning relief formed in the collar coupling surface and each collar positioning device comprises a correspondingly formed protrusion element extending from a nominal surface of the lower side of the post collar in a direction that is parallel to the longitudinal axis, or - each collar positioning device comprises a positioning relief formed in the nominal surface of the lower side of the post collar and each positioning element of the post holder body comprises a correspondingly formed protrusion element extending from the collar coupling surface in a direction that is parallel to the longitudinal axis. - each positioning element of the post holder body comprises a positioning relief formed in the collar coupling surface and each collar positioning device comprises a correspondingly formed protrusion element extending from a nominal surface of the lower side of the post collar in a direction that is parallel to the longitudinal axis, or - each collar positioning device comprises a positioning relief formed in the nominal surface of the lower side of the post collar and each positioning element of the post holder body comprises a correspondingly formed protrusion element extending from the collar coupling surface in a direction that is parallel to the longitudinal axis.