Collinear　calibration　is　a　typical　and　common　method　for　a　laser　(heterodyne)　interferometer,　but　it　usually　suffers　from　the　influence　of　the　tilt　of　the　target　retroreflectors　and　the　dissymmetry　of　the　optical　paths　during　the　calibration.　This　paper　mainly　analyzes　and　models　the　calibration　error　caused　by　the　tilt　error　of　the　target　retroreflectors　and　reveals　the　error　source　that　is　the　disturbance　from　the　rotary　error　of　the　guideway　slider　pair.　Experimental　results　prove　the　validity　of　the　analysis　and　model　of　the　calibration　error.　The　calibration　error　is　up　to　0.5　mu　m　when　the　tilt　error　is　0.36　degrees,　which　is　large　enough　to　equal　the　maximum　tolerance　of　laser　interferometer　(0.5　mu　m)　in　use.　(C)　2013　Optical　Society　of　America