Zoom lens apparatus

摘要

A zoom lens apparatus having a first pair of substantially parallel guide rods. A pair of carriage assemblies are mounted to the first pair of parallel guide rods each having lens element. A pair of lead screws are provided for driving the carriage assemblies. The screws are each mounted to the apparatus by a bearing block assembly such that the longitudinal axis of the lead screw is substantially parallel to the first pair of guide rods. The bearing block constrains the movement of the first lead screw along the longitudinal axis. A zero constraint threaded drive coupling is provided with each lead screw for moving the carriage along the guide rods. A motor is provided for rotating each of the drive screws.