Inertial pendulum optical stabilizer

Abstract

An inertial pendulum stabilizer is utilized for stabilizing the lens train of an optical instrument to be stabilized, such as a television camera, against accidental angular motion. A substantially spherical optical doublet having a leading negative lens element and a trailing positive element with both lens elements together being afocal is utilized. The leading negative lens element is fixed in front of the lens train of the optical instrument to be stabilized. An inertial pendulum has the positive optical element lens fixed to the front of the pendulum, this positive element being located between the leading negative lens and the lens train of the optical element to be stabilized. The inertial pendulum pivots on two intersecting and mutually perpendicular axes. The inertial pendulum is attached to the lens train to be stabilized so that the two mutually perpendicular and intersecting pivot axes intersect the lens train of the optical element to be stabilized. Consequently, this inertial pendulum defines an interior spatial interval exceeding the dimensions of the lens train of the optical instrument to be stabilized to enable pivot around the lens train with stabilizing excursion of the positive lens element. The inertial pendulum is counter-weighted so that the center of gravity of the pendulum is coincident to the point of intersection of the mutually perpendicular pivot axes of the pendulum. The pendulum is thus neutral to the ambient gravitational field but responsive to forces of its own inertia relative to the camera. The inertial pendulum is biased to a neutral position with respect to the lens train at low frequencies of angular motion and provided with suitable damping to minimize low frequency oscillation of the pendulum with respect to the optical train during panning of the instrument. An optical stabilizer with minimum increase in dimension relative to the optical train of the instrument to be stabilized results.