Hyett, AJ, Charette, FC, Forbes, BJ & Engbretson, AC 2014, 'Enlightening bolts', in M Hudyma & Y Potvin (eds), Deep Mining 2014: Proceedings of the Seventh International Conference on Deep and High Stress Mining, Australian Centre for Geomechanics, Perth, pp. 315-328, https://doi.org/10.36487/ACG_rep/1410_21_Hyett (https://papers.acg.uwa.edu.au/p/1410_21_Hyett/) Abstract: An experimental application of distributed optical sensing is presented for measuring the strain profile along fully grouted rockbolts. Standard optical fibre was encapsulated with epoxy resin into two diametrically opposed grooves machined into standard #6 rebar and 21 mm D-Bolt. To demonstrate the capabilities of the technique laboratory tests were conducted that simulate in situ bolt deformation related to bending, axial loading and shearing. For simple bending tests the measured strain profiles agreed well (+/- 5%) with theoretical predictions. Results for axial loading agree qualitatively with theoretical models, and exhibit sufficient resolution to detect the influence of the deformed rebar ribs. Shearing results show in detail, for the first time, the distinctive coupled contraction/extension pattern predicted from theoretical studies.