Abstract: A head-mountable device can include a display, a facial interface attached to the display to contact a face of a user, and a sensor unit attached to the facial interface. The sensor unit can include a deformable pad that contacts a nasal region of the user, a channel defining an internal volume, and a pressure sensor in fluid communication with the deformable pad through the internal volume.

Abstract: Mechanical apparatus includes a rotational assembly, including a frame and a gimbal, which is attached to the frame by first hinges disposed along a first axis and is configured to rotate on the first hinges about the first axis relative to the frame. A rotating element is attached to the gimbal by second hinges disposed along a second axis, perpendicular to the first axis, and is configured to rotate on the second hinges about the second axis relative to the gimbal. One or more strain sensors are disposed on at least one of the first hinges and configured to provide a signal indicative of a rotation of the rotating element about the second axis relative to the gimbal. Control circuitry is configured to monitor the rotation of the rotating element about the second axis responsively to the signal.

Abstract: An opto-mechanical unit that comprises a tunable filter, a holder that surrounds the tunable filter, and mechanically-damping and gluing gel; wherein the holder is spaced apart from the tunable filter; wherein the mechanically-damping and gluing gel surrounds the tunable filter and is attached to the holder and to the tunable filter; and wherein the holder comprises a camera interface that (a) defines a first inner space, and (b) introduces a gap between the tunable filter and the camera interface.