Abstract: A mechanism for orienting a payload support includes first and second transversely deployed drive assemblies, each having a motor that drives a drive arm. The payload support is directly pivotally mounted to a first drive arm. Connection between the second drive arm and the payload support is via a coupling linked to the second drive arm via a coupling rotary joint, and to the payload support via a support rotary joint. Both the first drive arm and the second drive arm are supported relative to the frame by sets of two bearing assemblies located on opposite sides of the center of rotation. Each of the bearing assemblies is preferably implemented as a loaded duplex bearing assembly, and most preferably with a back-to-back loaded duplex bearing assembly on each axis.

Abstract: A temperature compensated spacer includes first and second anchoring configurations for anchoring the spacer relative to first and second elements, and a frame providing a mechanical connection between the anchoring configurations. The frame has a polygonal opening with a first diagonal extending across the width of a gap between the elements and a second diagonal extending transversely to the first diagonal. A crossbar is associated with the polygonal opening so as to span the second diagonal. The frame and the crossbar are formed from materials having differing coefficients of thermal expansion. The crossbar is deployed so as to determine a length of the second diagonal such that variation in temperature causes deformation of the frame, thereby varying a length of the first diagonal.

Abstract: A total inner reflection (TIR) prism comprises two essentially triangular prisms separated by an optical coating or by a thin layer of air, wherein one of said two triangular prisms is shaped as an isosceles triangle.