Abstract

A plumb laser beam generator includes an internal self-leveling feature to assure the projection of a substantially plumb beam despite tilt of the instrument's housing. Tilt compensation is achieved in preferred embodiments using the angular deflection of a spring due to gravity along with the compensating angular magnification of a telescope which moves pendulously by support on the spring. A laser diode of the instrument is mounted fixedly in the housing, and the telescope resides above the diode and collimating optics, the telescope either hanging by a spring or supported at its base by a spring. The pendulous telescope preferably is motion-damped and includes motion limiting and shock absorbing devices to prevent damage due to sudden acceleration or dropping.