A medical apparatus comprising: a shaft (211, 511); a jaw assembly (212, 512) coupled to the shaft, the jaw assembly comprising a first jaw member (212a, 512a) and a second jaw member (212b, 512b), the first jaw member comprising a first gripping surface, an exterior surface reverse of the first gripping surface, and a transparent portion comprising a transparent material spanning a thickness of the first jaw member from the first gripping surface to the exterior surface, and the second jaw member comprising a second gripping surface opposing the first gripping surface; wherein the jaw assembly is configured to grasp material between the first and second gripping surfaces; wherein the apparatus further comprises: a sensor (20, 220, 526) at a location external to the jaw assembly and configured to sense light transmitted through the transparent portion; and a controller operably coupled to the sensor, the controller configured to process sensed light data output by the sensor and to detect deformation, detect slip, or both detect deformation and detect slip of material grasped by the jaw assembly based on processing the sensed light data. a shaft (211, 511); a jaw assembly (212, 512) coupled to the shaft, the jaw assembly comprising a first jaw member (212a, 512a) and a second jaw member (212b, 512b), the first jaw member comprising a first gripping surface, an exterior surface reverse of the first gripping surface, and a transparent portion comprising a transparent material spanning a thickness of the first jaw member from the first gripping surface to the exterior surface, and the second jaw member comprising a second gripping surface opposing the first gripping surface; wherein the jaw assembly is configured to grasp material between the first and second gripping surfaces; wherein the apparatus further comprises: a sensor (20, 220, 526) at a location external to the jaw assembly and configured to sense light transmitted through the transparent portion; and a controller operably coupled to the sensor, the controller configured to process sensed light data output by the sensor and to detect deformation, detect slip, or both detect deformation and detect slip of material grasped by the jaw assembly based on processing the sensed light data. the jaw assembly comprising a first jaw member (212a, 512a) and a second jaw member (212b, 512b), the first jaw member comprising a first gripping surface, an exterior surface reverse of the first gripping surface, and a transparent portion comprising a transparent material spanning a thickness of the first jaw member from the first gripping surface to the exterior surface, and the second jaw member comprising a second gripping surface opposing the first gripping surface; wherein the jaw assembly is configured to grasp material between the first and second gripping surfaces; wherein the apparatus further comprises: a sensor (20, 220, 526) at a location external to the jaw assembly and configured to sense light transmitted through the transparent portion; and a controller operably coupled to the sensor, the controller configured to process sensed light data output by the sensor and to detect deformation, detect slip, or both detect deformation and detect slip of material grasped by the jaw assembly based on processing the sensed light data. a sensor (20, 220, 526) at a location external to the jaw assembly and configured to sense light transmitted through the transparent portion; and a controller operably coupled to the sensor, the controller configured to process sensed light data output by the sensor and to detect deformation, detect slip, or both detect deformation and detect slip of material grasped by the jaw assembly based on processing the sensed light data.