A system, comprising: a sensor device; and an optical sensing module being a computer program product accessible from a computer-usable or computer-readable storage medium providing program code for use by or in connection with a computer or any instruction execution system; wherein the sensor device comprises a flexible instrument including at least one lumen, and a plurality of shape or strain sensing optical fibers (14, 16., 18) integrated in the flexible instrument in the at least one lumen and extending over a length of the flexible instrument; wherein the plurality of optical fibers are configured for measuring movement relative to one another to sense a change in distance between the plurality of optical fibers to detect a state of a reconfigurable portion of the flexible instrument, wherein the plurality of optical fibers comprise: a principal fiber extending the length of the flexible instrument for measuring the shape of the flexible instrument along the length of the flexible instrument and comprising a first launch position at a proximal position of the sensor device; and at least one supplemental optical fiber (16, 18) extending the length of the flexible instrument and configured to provide shape or strain sensing for measuring the shape of the reconfigurable portion of the flexible instrument, wherein the at least one supplemental optical fiber (16, 18) comprises a secondary launch region at or near the reconfigurable portion from which the shape of the reconfigurable portion is to be reconstructed; wherein the optical sensing module is configured to interpret the digitized optical signals from the principal fiber to reconstruct the shape of the flexible instrument and to interpret the digitized optical signals from the at least one supplemental optical fiber (16, 18) to reconstruct only the shape of the reconfigurable portion. a sensor device; and an optical sensing module being a computer program product accessible from a computer-usable or computer-readable storage medium providing program code for use by or in connection with a computer or any instruction execution system; wherein the sensor device comprises a flexible instrument including at least one lumen, and a plurality of shape or strain sensing optical fibers (14, 16., 18) integrated in the flexible instrument in the at least one lumen and extending over a length of the flexible instrument; wherein the plurality of optical fibers are configured for measuring movement relative to one another to sense a change in distance between the plurality of optical fibers to detect a state of a reconfigurable portion of the flexible instrument, wherein the plurality of optical fibers comprise: a principal fiber extending the length of the flexible instrument for measuring the shape of the flexible instrument along the length of the flexible instrument and comprising a first launch position at a proximal position of the sensor device; and at least one supplemental optical fiber (16, 18) extending the length of the flexible instrument and configured to provide shape or strain sensing for measuring the shape of the reconfigurable portion of the flexible instrument, wherein the at least one supplemental optical fiber (16, 18) comprises a secondary launch region at or near the reconfigurable portion from which the shape of the reconfigurable portion is to be reconstructed; wherein the optical sensing module is configured to interpret the digitized optical signals from the principal fiber to reconstruct the shape of the flexible instrument and to interpret the digitized optical signals from the at least one supplemental optical fiber (16, 18) to reconstruct only the shape of the reconfigurable portion. a principal fiber extending the length of the flexible instrument for measuring the shape of the flexible instrument along the length of the flexible instrument and comprising a first launch position at a proximal position of the sensor device; and at least one supplemental optical fiber (16, 18) extending the length of the flexible instrument and configured to provide shape or strain sensing for measuring the shape of the reconfigurable portion of the flexible instrument, wherein the at least one supplemental optical fiber (16, 18) comprises a secondary launch region at or near the reconfigurable portion from which the shape of the reconfigurable portion is to be reconstructed; wherein the optical sensing module is configured to interpret the digitized optical signals from the principal fiber to reconstruct the shape of the flexible instrument and to interpret the digitized optical signals from the at least one supplemental optical fiber (16, 18) to reconstruct only the shape of the reconfigurable portion.