Patent ID: 9291918
Filing Date: 2016-03-22
CPC Classification: G01B,G02F,G03F

Claim Text:
1. A beam adjuster assembly for a measurement system of a lithography system for measuring displacement of a stage which retains a substrate for a lithography process of the lithography system, the beam adjuster assembly receiving an input beam and providing a first output beam and a spaced apart second output beam, the beam adjuster assembly comprising: a first frequency adjuster that receives the input beam, the first frequency adjuster transmitting a first portion of the input beam without any change in frequency to provide the first output beam having a first output frequency, and the first frequency adjuster adjusting a frequency of a second portion of the input beam to provide a first adjusted beam; and a second frequency adjuster that receives the first adjusted beam, the second frequency adjuster adjusting the frequency of at least a portion of the first adjusted beam to provide the second output beam having a second output frequency that is different than the first output frequency.