Patent ID: 6847457

Claim:
An interferometer for analyzing a dimension of an object based on interleaved multiple phase-shifted interference information, comprising: a transmitting portion that directs first and second differently polarized lights from a coherent light beam to a reference element and an object, respectively, combines the first and second differently polarized lights returned from the reference element and the object into a combined wavefront, and outputs the combined wavefront; and a multiple phase shift image generating portion arranged to input the combined wavefront, the multiple phase shift image generating portion comprising: at least a first relative retardation array arranged along at least a first optical path, the first relative retardation array comprising at least two respective pluralities of relative retardation portions, each respective plurality of relative retardation portions comprising relative retardation portions of a single respective type that produces a respective amount of relative phase shift when transmitting the first and second differently polarized lights, the at least two respective pluralities of relative retardation portions arranged in an interleaved pattern within the first relative retardation array, and a first polarizer element arranged along the first optical path; and a detector portion comprising at least a first detector array arranged along the first optical path; wherein: the first relative retardation array receives at least a sub-wavefront of the combined wavefront including the first and second differently polarized lights; each of the at least two respective pluralities of relative retardation portions transmits the first and second differently polarized lights of the sub-wavefront through the first polarizer element, each respective plurality of relative retardation portions in combination with the first polarizer element producing at least one respective plurality of interference portions along the first optical path, each of the respective pluralities of interference portions produced along the first optical path comprising interference light having a single respective relative phase shift; and the multiple phase shift image generating portion outputs interleaved multiple phase-shifted interference image information from at least the first optical path, the interleaved multiple phase-shifted interference image information output from the first optical path comprising the respective pluralities of interference portions produced along the first optical path, mutually interleaved in a pattern determined at least partially by the interleaved pattern of the respective pluralities of relative retardation portions in the first relative retardation array.