Recent developments of novel optical concepts for a variety of new applications has presented a significant challenge to manufacturers of precision optical components. These applications include astronomy in the extreme ultraviolet and soft through hard x-ray spectral regions, resonator and beam handling optics for free electron lasers, microscopes for plasma diagnostics, and focusing elements for synchrotron radiation. Along with the challenge of manufacturing these components to ever increasing levels of surface quality and smoothness, has come the corresponding challenge of measuring and localizing surface defects to even greater accuracy.
This paper treats the process of accommodating extreme measurement geometries, including aspheric cylindrical surfaces, and describes an absolute calibration technique for linear surfaces capable of 0.0067λ. (42Å) p-p with a precision (1-σ) of 0.0008λ. (5Å) rms.