A system comprising: an elongate instrument body; an optical fiber sensor coupled to the elongate instrument body and forming a strain sensor, the optical fiber sensor comprising a core including Fiber Bragg gratings; and a system for calibrating said optical fiber sensor associated with said elongate instrument body of an elongate instrument, comprising: a calibration fixture configured to position the elongate instrument body in a known geometric configuration; wherein said calibration fixture has a groove in which the elongate instrument body and the optical fiber sensor can be positioned in said known geometric configuration, and a controller (300, 340) configured to: (i) receive, from an external source, information indicative of the known geometric configuration of the elongate instrument body; (ii) determine a sensed geometric configuration based on signals received from the strain sensor of the optical fiber sensor while the elongate instrument body positioned in the groove of the calibration fixture is in the known geometric configuration, and (iii) compare the sensed geometric configuration of the strain sensor with the known geometric configuration of the elongate instrument body. an elongate instrument body; an optical fiber sensor coupled to the elongate instrument body and forming a strain sensor, the optical fiber sensor comprising a core including Fiber Bragg gratings; and a system for calibrating said optical fiber sensor associated with said elongate instrument body of an elongate instrument, comprising: a calibration fixture configured to position the elongate instrument body in a known geometric configuration; wherein said calibration fixture has a groove in which the elongate instrument body and the optical fiber sensor can be positioned in said known geometric configuration, and a controller (300, 340) configured to: (i) receive, from an external source, information indicative of the known geometric configuration of the elongate instrument body; (ii) determine a sensed geometric configuration based on signals received from the strain sensor of the optical fiber sensor while the elongate instrument body positioned in the groove of the calibration fixture is in the known geometric configuration, and (iii) compare the sensed geometric configuration of the strain sensor with the known geometric configuration of the elongate instrument body. a calibration fixture configured to position the elongate instrument body in a known geometric configuration; wherein said calibration fixture has a groove in which the elongate instrument body and the optical fiber sensor can be positioned in said known geometric configuration, and a controller (300, 340) configured to: (i) receive, from an external source, information indicative of the known geometric configuration of the elongate instrument body; (ii) determine a sensed geometric configuration based on signals received from the strain sensor of the optical fiber sensor while the elongate instrument body positioned in the groove of the calibration fixture is in the known geometric configuration, and (iii) compare the sensed geometric configuration of the strain sensor with the known geometric configuration of the elongate instrument body. (i) receive, from an external source, information indicative of the known geometric configuration of the elongate instrument body; (ii) determine a sensed geometric configuration based on signals received from the strain sensor of the optical fiber sensor while the elongate instrument body positioned in the groove of the calibration fixture is in the known geometric configuration, and (iii) compare the sensed geometric configuration of the strain sensor with the known geometric configuration of the elongate instrument body.