Abstract: A viewing device to aid in authenticating an optical surface. The device includes a laser diode which produces a beam of light. The device includes a viewing screen which receives a diffracted image produced by the beam illuminating the surface. The device further includes a lens system which causes the diffracted beam to be focused on the viewing screen.

Abstract: A traction splint for attachment to a person's leg for example and having an elongate U-shape frame. The side arms of the frame are telescopic and an air pump is connected to the frame so as to be operable to cause simultaneous extension of the two arms. A foot retaining device is attached to the arms adjacent the base of the U and a thigh ring is releasably securable to the movable sections of the two arms so that extension or contraction of the arms causes variation in the distance between the thigh ring and the foot retaining device. The thigh ring is completely separable from the arms and retaining structure is operable to prevent that separation. Also, the thigh ring can be opened at one side to allow it to be moved laterally over a person's leg.