| 摘要 |
In one embodiment, an interferometer system comprises two unequal path interferometers assemble comprising; a first reference flat having a first length L1 in a first dimension, a second reference flat having a second length L2 in the first dimension, a cavity D1 defined by a distance between the first reference flat and the second reference flat, a wafer holder to receive an object in the cavity such that an optical path remains open at an outer annual area between the first reference flat and the second reference flat and at least one wafer holder motor coupled to the wafer holder such that an object may be tilted in the cavity as to allow for measurements of local areas of interest, and a radiation targeting assembly to direct a collimated radiation beam to the interferometer assembly, a radiation collecting assembly to collect radiation received from the interferometer assembly, and a controller comprising logic to; vary a wavelength of the collimated radiation beam, record interferograms formed by a plurality of surfaces, extract phases of each of the interferograms for each of the plurality of surfaces to produce multiple phase maps, determine each map from its corresponding interferogram, determine from each map local areas of interest with high slopes, tilt the wafer holder to allow measurement of the high slope areas of interest, and process measurement that covers the entire surface of an object including high slope areas.
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