This　work　proposes　a　novel　contactless　sensor　to　measure　the　micro　torque　of　a　rotating　shaft　based　on　the　optical　coherence　displacement　measurement　(OCDM)　principle.　The　experimental　system　features　a　simple　mechanical　testing　system　to　measure　the　torque,　a　calibration　device　to　establish　the　measurement　baseline,　and　a　polyetheretherketone　(PEEK)　shaft　to　improve　the　theoretical　resolution　of　the　system　up　to　0.003　Nm.　The　torque　measurement　results　indicate　that　this　sensor　achieved　a　maximum　nonlinearity　error　of　0.0484　%,　maximum　repeatability　error　of　0.2771　%,　and　maximum　hysteresis　error　of　0.2252　%.　This　high　accuracy　of　our　system　stems　from　the　use　of　high-precision　optical　principles　and　the　novel　physical　mapping　of　the　torque　(i.e.,　processing　scales　on　the　shaft　surface　to　represent　the　twist　angle　by　designing　a　laser　engraving　system)　capable　of　resisting　the　negative　effects　of　radial　vibrations.　Additionally,　our　torque　measurement　sensor　possesses　broader　applicability　by　effectively　resisting　the　impacts　of　temperature　variations　and　electromagnetic　interference.　These　attributes　make　it　excel　other　torque　sensors　presented　in　the　literature　in　recent　years.　©　2023　Elsevier　Ltd