Abstract: A position encoder for monitoring position of an object includes a target pattern, an illumination system, an image sensor, and a control system. The illumination system generates (i) a first illumination beam that is directed toward and impinges on the target pattern, the first illumination beam having a first beam characteristic; and (ii) a second illumination beam that is directed toward and impinges on the target pattern, the second illumination beam having a second beam characteristic that is different than the first beam characteristic. The image sensor is coupled to the object and is spaced apart from the target pattern. The image sensor senses a first set of information from the first illumination beam impinging on the target pattern and senses a second set of information from the second illumination beam impinging on the target pattern. The control system analyzes the first set of information and the second set of information to monitor the position of the object.

Abstract: An actuator assembly (16) for moving a device (22) includes a stator component (30), a mover component (32), a measurement system (18), and a signal processor (20). The measurement system (18) includes (i) a magnet assembly (244) that is coupled to and moves with the mover component (32); and (ii) a plurality of spaced apart sensors (246A). The magnet assembly (244) produces a magnetic field (244B) that moves relative to the stator component (30) as the mover component (32) moves along a mover axis (32C). Each sensor (246A) is a transducer that generates a sensor signal that varies its output voltage in response to the changing magnetic field (244B) from the magnet assembly (244) as the mover component (32) is moved relative to the sensors (246A). The signal processor (20) receives the sensor signals and estimates a position of the mover component (32) along the mover axis (32C) based at least in part on the sensor signals.

Abstract: A stage assembly for positioning a device includes: (i) a stage that retains the device; (ii) a base; (iii) a mover assembly that moves the stage along a first axis, along a second axis, and along a third axis relative to the base; (iv) a magnetic sensor system that monitors the movement of the stage along the first, second and third axes, the magnetic sensor system generating a magnetic sensor signal; (v) a second sensor system that monitors the movement of the stage along the first, second and third axes, the second sensor system generating a second sensor signal; and (vi) a control system that controls the mover assembly using at least one of the magnetic sensor signal and the second sensor signal.

Abstract: According to one aspect, an apparatus includes a stage, a motor to move the stage, an amplifier, and a controller. The motor has at least a first coil and a second coil, and the amplifier is configured to selectively provide current to either the first coil or the second coil. The controller is configured to control force generated by the motor. When moving the stage, the controller controls the motor force by using the amplifier to provide current to the first coil, smoothly reducing a force generated by the first coil before the stage moves to a predetermined switching location so that the coil is generating substantially no force at the switching location, switching the amplifier so that the amplifier provides current to the second coil, and smoothly increasing a force generated by the second coil after the stage moves past the predetermined switching location.

Abstract: A stage assembly for positioning a device includes: (i) a stage that retains the device; (ii) a base; (iii) a mover assembly that moves the stage along a first axis, along a second axis, and along a third axis relative to the base; (iv) a magnetic sensor system that monitors the movement of the stage along the first, second and third axes, the magnetic sensor system generating a magnetic sensor signal; (v) a second sensor system that monitors the movement of the stage along the first, second and third axes, the second sensor system generating a second sensor signal; and (vi) a control system that controls the mover assembly using at least one of the magnetic sensor signal and the second sensor signal.