A guide roller for a continuous casting machine includes a roller seat having bearings, a roller shaft mounted for rotation in the roller seat and at least one roller body mounted on the roller shaft and configured to support a billet. A passive optical sensor is mounted to the roller seat and configured to output optical signals, and an optical fiber extends from the passive optical sensor and is configured to convey the optical signals to a processor configured to determine one or more physical parameters of an installation position of the passive optical sensor based on the optical signals.