| 摘要 |
A system and method are used to determine a parameter (e.g., angle, position, orientation, etc.) of a device. A first portion includes a source of radiation configured to produce a beam of radiation that is directed to be reflected from a reflective portion of the device. A second portion is coupled to the first portion and includes a measurement device and, optionally, a detector, such that the reflected beam transmits through the measurement device onto the detector. The parameter of the device is determined based on the interaction of the reflected beam and the measurement device. In one example, the first and second portions can form a folded optical encoder that measures an angle of a scanning mirror or a position or orientation of a stage within a lithography apparatus. |
