Abstract: Fluid damper for damping aiming movements, for instance when tracking a target. The damper comprises a substantially disc-shaped cylindrical housing (9) in which a drum-wheel (11) is supported for rotation so that an inner gap spacing (24) is provided between the drum-wheel and a slipping ring (14) integrated in the outer cylindrical wall (13) of the damper housing. Said gap spacing (24) is filled with a high-viscosity damping fluid so that a damping torque is obtained which is linearly increasing to the angular velocity for velocities up to a certain level but which are limited for velocities exceeding said level due to the fact that the slipping ring (14) starts rotating with respect to the other parts of the damper housing. The slipping ring (14) is made of a material which is temperature stable and which can be made with a high accuracy with respect to its dimensions for instance carbon-fibre reinforced epoxy resin.

Abstract: This invention relates to a device for use when evaluating optical signals by means of a chopper (2, 2'), i.e. a rotating shutter, and a photodetector (6, 6') for detecting the signal transmitted through the chopper (2, 2'). In order to improve the evaluation of the incident signal the opaque part (3, 3') of the chopper is provided with a reflective surface (7) to utilize also the optical signal falling on the opaque part (3, 3'). An additional photodetector (9, 9') has been arranged for detecting this reflected optical signal. In order to reduce the energy losses and in this way increase the amplification of the optical signal the device also comprises an optical element in the form of a glass prism (10, 10') in which one and the same surface is utilized both for transmitting and reflecting the optical signal.

Abstract: An optical system for determining the angular deviation of a movable object from a pre-selected target, wherein an objective lens projects an image of the target in a first focal plane and projects an image of the movable object in a further focal plane. A prism divides the images, with the target image being tramsmitted to an ocular and the movable object image being transmitted to a detector.