A torsion measurement device is disclosed. In one embodiment, the device includes a component having a marked surface and an optical sensor. The marked component and the optical sensor may be attached to a tube or other elongate member and positioned to enable the optical sensor to measure angular deflection of the tube from rotation of the marked component with respect to the optical sensor. The angular deflection may be combined with other data to determine applied torque and torsional stress on the tube or other elongate member. Additional systems, devices, and methods are also disclosed.