| 摘要 |
A new and useful metrology system is provided, of a type that comprises an optical cavity of the hemispherical or spherical type, with a vibrating mirror not located at or near a focus of the optical cavity, and which is particularly useful as a non interferometric metrology system. In one of its basic aspects, the metrology system measures changes in orientation of a vibrating mirror, by providing an optical cavity that includes reflection of a measurement beam from the vibrating mirror, where the optical cavity is configured such that an object space that includes the vibrating mirror is a conjugate image of the same object space. In another of its basic aspects, a metrology system according to the present invention has a measurement beam that is reflected from the vibrating mirror, where the vibrating mirror and a reference mirror are in a relationship in which reflection of the measurement beam from the vibrating mirror is then reflected from the reference mirror in a manner that establishes a local reference system for measuring changes in the orientation of the vibrating mirror.
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