Patent ID: 9726987
Date: 2017-08-08
CPC Classifications: G01D,G03F,H02K

Claim:
1. A stage assembly for positioning a device along a first axis, the stage assembly comprising: a base; a stage that is adapted to retain the device and moves above the base; a mover assembly that moves the stage along the first axis relative to the base; a first sensor system that monitors the movement of the stage along the first axis, the first sensor system generating a first signal, the first sensor system having a first sensor accuracy, the first sensor system including at least one optical sensor, the first sensor system capturing a plurality of successive images and monitoring the movement of the stage by comparing at least two images to generate the first signal; a second sensor system that monitors the movement of the stage along the first axis, the second sensor system having a second sensor accuracy that is different from the first sensor accuracy of the first sensor system, the second sensor generating a second signal; and a control system that controls the mover assembly using at least one of the first signal and the second signal.