Optical instrument with stabilized reflecting component mounted as inverted pendulum

Claim 1

An automatic leveling instrument for sighting objects along a level optical line of sight, comprising a housing, a sighting optical system provided in said housing And including an objective, a reticule and an eyepiece, a reflecting optical system provided in the light path between said objective and said reticule and including a first reflecting optical component fixedly mounted in said housing and a second reflecting optical component movably related to said first reflecting optical component for bending the line of sight, and means for mounting said second reflecting optical component as an inverted pendulum body comprising a transverse support member defining an effective axis of rotation for the inverted pendulum body perpendicular to the vertical plane containing the optical line of sight, a pair of elastic deformable threads attached to each end of said transverse support member on said axis of rotation, each pair of threads forming a triangular suspension with the upper ends attached to spaced points on said housing, said second reflecting optical component being mounted on said transverse support member in upwardly spaced relationship to said axis of rotation and the center of gravity of the inverted pendulum body lying between said axis of rotation and said spaced attachment points on said housing, whereby angular tilting of said housing produces a magnified angle of tilt of said second reflecting optical element in the same direction, controlled by the bending deformation of said pairs of threads.